Telecom Power Systems & Electrical Insulation
H-O Products die-cuts and converts the insulation set inside −48 VDC telecom power plants: Kapton® polyimide busbar wrap, Nomex® aramid phase barriers and slot liners, flame-rated polypropylene barrier stock in the Formex™-class family, G10/FR4 and G11 glass-epoxy creepage extenders, mica arc-adjacent barriers, and the PORON® and polyimide layers inside battery backup unit (BBU) shelves, built to your drawing.
Built for: −48 VDC power plant busbar and battery-return insulation, rectifier and PDU phase barriers, ferroresonant and switchmode magnetics, creepage and clearance extender plates, lithium and VRLA BBU shelf insulation, and the arc-flash-adjacent barrier layers that support equipment designs evaluated to the customer's standards program, with every standard cited by designation.
To insulate a −48 VDC telecom power plant, work job by job. Busbar wrap and barriers: Kapton® HN polyimide film where the insulation bends and wraps, aramid insulation paper (Nomex®) where a tough, conformable paper suits the joint, and G10/FR4 glass-epoxy where the insulation also carries load.
Rectifier and PDU phase barriers: flame-rated polypropylene barrier stock in the Formex™-class family (cited by family designation, properties per vendor TDS) or die-cut Nomex® 410, with Norplex FR4 (NP510A) where stiffness matters. Magnetics: Nomex® 410/414 slot and layer insulation with 818 aramid-mica paper and Kapton® FN heat-sealable constructions.
Creepage and clearance extenders: Norplex G11 (NP511), Durostone® composite, and muscovite mica plates and channels, with spacing decisions per the equipment design's IEC 60664 practice. BBU shelves: PORON® 4701-40V0 pads (UL 94 V-0 class per its TDS) plus mica fire-barrier sheet supporting designs evaluated to UL 1973 at the system level.
Arc-flash-adjacent barriers: ManniGlas® glass-fiber paper and phlogopite mica, supporting programs framed by NFPA 70E and IEEE 1584 at the facility level.
All standards by designation; values per the maker TDS on file; final material selection should be validated in the application. See the quote form for ordering details.
System-, equipment-, and facility-level, by designation (the evaluation belongs to the customer's tested design or program): IEC 60664 (insulation coordination for low-voltage systems) · UL 1973 (batteries for stationary applications, the BBU system tier) · Telcordia GR-3108 (network equipment in the outside plant, as design context) · NFPA 70E and IEEE 1584 (workplace electrical safety and arc-flash study practice).
Material-level, per the maker TDS: UL 94 (flammability classes, including V-0 on the listed grades) · ASTM D149 (dielectric breakdown methods) · NEMA LI 1 (industrial laminate grade designations, G10/FR4/G11) · IEC 60085 (thermal class framework referenced on insulation TDSs).
- Busbar wrap (bends, wraps): Kapton® HN film
- Busbar supports (carries load): G10/FR4 laminate
- Phase barriers (fold, live-front): Formex™-class flame-rated PP / Nomex® 410
- Slot & layer insulation: Nomex® 410 / 414
- Heat-sealable wraps: Kapton® FN
- Creepage / clearance extenders: G11 (NP511) / Durostone®
- BBU shelf pads: PORON® 4701-40V0
- BBU fire-barrier layer: mica fire-barrier sheet
- Arc-adjacent barriers: ManniGlas® 1900 / phlogopite mica
- Thin dielectric on a budget: fish paper / PET film (family level)
Where are you in the spec process?
This page serves engineers who already have insulation callouts on the drawing and engineers still deciding which family carries each job. Pick the path that matches where you are; you don't have to read the rest.
Send a drawing, get a quote
A Kapton® gauge, a Nomex® designation, a laminate grade, a folded phase-barrier flat pattern, or a complete die-cut insulation kit on your drawing. Engineering reviews it against the maker TDSs and quotes it.
Skip to the quote form →Work the six jobs in order
Six numbered insulation jobs from the busbar out to the arc-flash boundary, each with engineering context, the material families that commonly carry it, and exactly what to put on the drawing.
Start with the busbar →
Where H-O parts do the work
−48 VDC plant busbar wrap & barriers
Engineering context. A telecom DC plant runs at a voltage low enough to lull a designer and a fault current high enough to punish one. The −48 VDC bus between rectifiers, distribution panels, and battery strings carries hundreds to thousands of amps, and its insulation problem is mechanical rather than voltage-driven: wraps that crease at busbar edges, barriers that rattle loose under cyclic load, films trimmed in the field with the wrong radius.
Battery-return conductors and live-front distribution add a second concern, the dropped-tool short, which is why plant practice covers exposed bus with insulating wrap and barrier layers wherever hands and hardware work overhead.
What H-O converts. Slit and Kapton® HN polyimide film busbar wraps and liners in the thin-gauge designations; aramid insulation paper (Nomex®) barrier sheets and joint covers; machined and G10/FR4 glass-epoxy supports, standoff plates, and inter-bus barriers; and economical vulcanized fibre (fish paper) and PET dielectric film converted at the family level for low-stress liners and covers.
Material-family guidance. Split the duty by mechanics, not by voltage. Kapton® film goes where the insulation bends and wraps: it follows busbar geometry at thin gauges, with dielectric methods (ASTM D149 class) on the maker TDS [2]. Nomex® paper goes where a conformable, thermally tough paper suits a joint cover or a folded barrier. G10/FR4 (NEMA LI 1 grade designations [4]) goes where the insulation also carries load: supports, standoffs, and barriers that take bolt torque.
Spacing decisions on the bus itself stay inside the equipment design's IEC 60664 insulation-coordination practice [1]; the films and laminates here are the materials those decisions get built from. Die-cut parts with accurate, sealed edges remove the field trimming that starts most wrap failures.
Busbar cross-section and bend radii, wrap or barrier geometry (a DXF flat pattern is ideal), film gauge or laminate thickness if already chosen, fastener locations and torque for load-bearing parts, and the fault-current or plant-practice note driving the coverage. "Recommend the family" is a valid callout.
Rectifier & PDU phase barriers
Engineering context. Rectifier shelves and power distribution units pack AC input, DC output, and control wiring into sheet-metal volumes measured in rack units. Phase barriers separate input phases, isolate AC from DC sections, and stand between field-wiring lugs and everything else. The classic construction is a die-cut, scored, and folded flat pattern: a barrier that ships flat, folds into a channel or box at assembly, and holds its shape without fasteners.
The material has to take the fold without cracking, hold a flammability class, and resist tracking across its surface where dust and humidity accumulate.
What H-O converts. Die-cut and scored flame-rated polypropylene barrier stock in the Formex™-class family, cited by family designation with flammability class, CTI performance, and dielectric data per the vendor TDS; Nomex® 410 barriers where thermal endurance drives the choice; and flat Norplex FR4 (NP510A) barrier plates where the part must stay rigid across a span. Kiss-cut barrier sets ship on liner in assembly order for shelf-level kitting.
Material-family guidance. Flame-rated polypropylene barrier stock is the folding workhorse of this job: it scores and folds into self-supporting shapes, and the listed grades carry UL 94 V-0 classes per the vendor TDS [3], with comparative tracking index data that matters in dusty, humid central-office and OSP-adjacent air. Aramid paper takes over where the barrier sits near heat: Nomex® designations carry their thermal-class context per the maker TDS [5].
Glass-epoxy laminate is the rigid option where a barrier doubles as a mounting plate. Commonly specified by flat-pattern drawing with score lines called out; the fold radius and grain direction belong on the drawing, because a fold that fights the material is the most common barrier failure at assembly.
The flat pattern with fold and score lines, material thickness, flammability class required on the part (UL 94 class per the vendor TDS), working temperature near the barrier, and quantities for prototype and production. If the barrier mounts with adhesive, note the substrate: adhesive performance depends on substrate, surface energy, temperature, exposure, dwell time, applied pressure, surface preparation, joint geometry, and the assembly process, and tape selections should be validated in the application.
Transformer slot & layer insulation
Engineering context. Telecom power conversion still turns on magnetics: ferroresonant transformers in legacy plants, high-frequency transformers and inductors in switchmode rectifiers, and the chokes and current-sense magnetics scattered through PDUs. Their insulation is a layered system: slot liners between winding and core, layer insulation between winding passes, wrappers over finished coils, and wedges and channel pieces holding it all in place.
Every layer is specified by designation and thickness off the winding drawing, and the thermal class of the insulation system frames the materials that can live in it.
What H-O converts. Slit and Nomex® 410 slot liners and layer insulation; Nomex® 414 where the higher-density grade suits the slot; Nomex® 818 aramid-mica paper for high-voltage wrap and tracking-resistant phase insulation (wedges and formed pieces are cut from laminate or pressboard stock to drawing); Kapton® FN heat-sealable polyimide for bonded wraps; and ManniGlas® glass-fiber paper where inorganic temperature endurance earns its place near hot spots.
Material-family guidance. Aramid paper is the default for slot and layer duty: conformable, slittable to narrow widths, with thermal-class context per IEC 60085 framing on the maker TDS [5] and dielectric methods per ASTM D149 [2]. Kapton® FN adds an FEP heat-seal layer for wraps that bond to themselves. Glass-fiber paper carries the hottest locations. The deep version of this playbook, across the full voltage range, lives on the busbar, transformer & motor insulation sibling page; this section is its telecom-plant edition.
Final material selection should be validated in the application against the insulation system's thermal class and the winding process.
The winding drawing or slot dimensions, material designation and thickness per layer, slit-width tolerances, any heat-seal or adhesive requirement, and the insulation system's thermal-class context. Slit-and-sheeted stock, liners, and kitted winding sets are all standard outputs on slitting and flatbed die-cutting.
Creepage & clearance extenders
Engineering context. When a layout cannot buy spacing with air, it buys it with material. Creepage extenders, barrier plates, channels, and collars placed between conductors lengthen the surface path a tracking fault would have to travel, and they rescue layouts where a retrofit, a denser shelf, or a field-wiring lug has eaten the margin the original design carried.
The governing logic is the equipment design's insulation-coordination practice per IEC 60664, which sets required creepage and clearance from working voltage, pollution degree, and material group; the extender is the part that makes those numbers achievable in the geometry that exists.
What H-O converts. Machined and G10/FR4 glass-epoxy barrier plates; Norplex G11 (NP511) where elevated temperature rides with the electrical duty; Durostone® composite laminate for structural insulating parts; and muscovite mica rigid sheet where inorganic, arc-adjacent behavior is wanted on the same part. Waterjet and CNC routing handle thick sections and tight internal features on waterjet cutting.
Material-family guidance. The laminate grades are specified by NEMA LI 1 designation [4], and the property that earns an extender its keep is comparative tracking index: a material that resists surface tracking lets the design claim more creepage per millimeter of part. Material group (per the CTI ranges referenced in IEC 60664 practice [1]) belongs on the drawing next to the dimension.
At −48 VDC the voltages are modest, but pollution degree in OSP cabinets and unfiltered central-office air is what drives the spacing table, and a barrier that survives bolt torque without cracking is a mechanical spec as much as an electrical one. May be suitable as folded polypropylene or aramid constructions instead where the extender does not carry load; the phase-barrier section above covers that family split.
Part geometry (DXF or STEP), laminate grade and thickness if chosen, required creepage dimension and material-group note from the equipment design, fastener loads, and working temperature. H-O converts the parts to drawing; the insulation-coordination analysis itself stays with the equipment designer.
BBU shelf & battery-cabinet insulation
Engineering context. Battery backup units bring the battery-module material stack into the telecom rack: lithium BBU shelves and VRLA strings both need dielectric isolation between cells and chassis, cushioning that holds cells against vibration and handling, and, in lithium designs, barrier layers that support the system's thermal-runaway strategy. The standards language is strict here: UL 1973 evaluates the battery system, the listing belongs to the tested assembly, and the layers inside support designs evaluated to it.
Outside-plant deployments add the GR-3108 operating-class context on top.
What H-O converts. Die-cut PORON® 4701-40V0 cell and module pads (UL 94 V-0 class per its TDS; compression methods per ASTM D3574) and the broader PORON® 4701 series for cushioning duty; Kapton® HN dielectric wraps and tray liners; mica fire-barrier sheet die-cut to the cell footprint; and kiss-cut multi-part kits on liner, one kit per shelf, through CNC knife cutting and kitting.
Material-family guidance. Specify compression pads by force window, not thickness: the cell maker's preload range and swell allowance pick the firmness grade off the compression-force-deflection data on the TDS. Dielectric layers follow the busbar logic above, film where it wraps, laminate where it bears. Fire-barrier layers are cited cautiously: the mica layer supports a thermal-runaway strategy evaluated on the tested system per the customer's UL 1973-framed program [6], and no layer carries that listing itself.
The full stationary-battery version of this stack lives on the data center power & UPS systems sibling page.
Cell or module footprint, preload window (kPa) and swell allowance for pads, wrap geometry and gauge for dielectric layers, barrier-tier strategy for lithium designs, and the standards language your documentation needs (material classes per TDS; system standards by designation).
Arc-flash-adjacent barriers
Engineering context. Where telecom DC plants meet utility AC, transfer switches, and generator switchgear, the facility's electrical-safety program (framed by NFPA 70E workplace practice and IEEE 1584 arc-flash study methods, both cited here by designation) shapes the hardware around live work: insulating covers over exposed terminations, barrier sheets behind panels, and high-temperature layers near equipment the study flags.
The honest framing matters: an arc-flash program belongs to the facility and its study; a barrier is a converted material inside that program, carrying its own TDS-documented properties and nothing more.
What H-O converts. Die-cut ManniGlas® 1900 and ManniGlas® 1200 glass-fiber paper barriers (the ManniGlas® family spans 1200–2000); muscovite and phlogopite mica rigid and flexible sheet for inorganic barrier duty; and Durostone® UPM 203-class composite for structural insulating covers. Thick sections cut clean on waterjet; thin sheet dies cleanly on flatbed tooling.
Material-family guidance. Inorganic chemistry is the through-line: mica and glass-fiber papers do not melt or contribute fuel at fault temperatures, which is why they recur wherever the study puts material between people and energy. Properties come off each maker TDS with the method named; flammability classes per UL 94 apply to the listed organic-bound grades [3].
The dedicated treatment of this family, including fire-barrier stacks and switchgear duty, lives on the arc flash & fire protection sibling page; this section places it in the telecom power room.
H-O supplies converted barriers and documentation; the arc-flash study, labeling, and program belong to the facility.
Barrier geometry and thickness, the material family or designation if the program names one, mounting method and fastener locations, working temperature, and the program context (by designation) your documentation should reference. Quantities for prototype and production close the loop.
The decisions that drive a power & electrical-insulation spec
Insulation for −48 VDC plant and power gear is chosen in order: the voltage and spacing, the temperature, and how close the part sits to an arc.
Size the part to the voltage and spacing first, then to the temperature, arc adjacency, and documentation the review asks for. Grades carry their own dielectric and thermal class per TDS.
Show all 5 selection factors tap to expand
Power & electrical-insulation failures you can prevent at spec
These surface as a flashover, a hot-spot breakdown, or a barrier that contributes fuel near an arc — all decided in the material callout.
These parts sit in a safety-critical path. Under-sizing creepage or placing a combustible barrier near arc-prone gear is where these specs go wrong.
Show all 5 failure modes tap to expand
1. Insufficient creepage on a busbar or phase barrier
Fix — size the barrier to IEC 60664 creepage and clearance for the working voltage and pollution degree.
2. Elastomer where slot or layer insulation runs hot
Fix — use mica or MannIGlas® glass-fiber matched to the IEC 60085 thermal class.
3. A combustible barrier near arc-flash gear
Fix — use inorganic, non-fuel-contributing mica or glass-fiber per the NFPA 70E context.
4. Undocumented dielectric strength
Fix — specify dielectric per ASTM D149 and the grade TDS.
5. Field-trimmed mica or glass-fiber
Fix — die-cut to the drawing with holes and tabs in place; field-trimming fractures mica and sheds dust.
Specification Tools
Two tools to take you from "we're building a −48 V plant shelf" to here's the insulation checklist for the drawing set: a job-driven checklist builder that assembles the layer list with its citation language, and a side-by-side comparison of every insulation family on this page.
1. −48 V plant insulation checklist builder
Check the insulation jobs your design carries. The builder assembles the corresponding material layers into a checklist with the family, what to send with the drawing, and the citation language (material classes per the maker TDS; system, equipment, and facility standards by designation). The default selection is pre-built for a typical rectifier-plus-distribution shelf; every layer is also printed in the material reference section, so nothing here exists only behind a script.
Insulation checklist: 3 layers selected
Each checked job adds its layer below. The list is the starting bill of materials for the engineering review, not a certification: material classes (UL 94) come from the grade TDS, and system, equipment, and facility standards (IEC 60664, UL 1973, NFPA 70E) are cited by designation with the evaluation belonging to the customer's tested design or program.
- Busbar wrap: Kapton® HN polyimide filmSend: busbar cross-section, bend radii, wrap geometry, gauge. Cite: dielectric methods per the maker TDS (ASTM D149 class).
- Supports: G10/FR4 glass-epoxy plates & standoffsSend: part geometry, thickness, fastener loads. Cite: NEMA LI 1 grade designation; spacing per the IEC 60664 design practice.
- Phase barriers: flame-rated PP (Formex™-class) or Nomex® 410Send: flat pattern with fold/score lines, thickness, flame class. Cite: UL 94 class and CTI per the vendor TDS.
2. Side-by-side: telecom power insulation family comparison
Every family called out on this page, with construction, the property that drives its selection, the standards its TDS cites, and the job it serves. Click a column header to sort. Click any material name to jump to its accordion entry.
| Material | Construction | Selection driver | Standards on the TDS / by designation | Job | |
|---|---|---|---|---|---|
| Films & papers (bend, wrap, fold) | |||||
| Kapton® HN / FN Polyimide FilmThin-gauge designations | Polyimide film | Bends & wraps at thin gauge | ASTM D149-class methods per maker TDS | Busbar wrap, BBU liners, bonded wraps | |
| Nomex® Aramid Paper (410 / 414 / 818)Aramid designations | Calendered aramid paper | Thermal endurance, conformability | IEC 60085 thermal-class context; D149 methods per TDS | Slot/layer insulation, barriers, joint covers | |
| Flame-Rated Polypropylene Barrier Stock (Formex™-class)Family designation | Scored & folded PP sheet | Folds into self-supporting shapes | UL 94 classes & CTI per vendor TDS | Rectifier / PDU phase barriers | |
| Fish Paper / PET Dielectric Film (family level)Films, papers & laminates family | Vulcanized fibre / polyester film | Economical low-stress liners | Per vendor TDS at the family level | Liners, covers, spacers | |
| Laminates & inorganics (bear load, buy distance, sit near energy) | |||||
| G10/FR4 & G11 Glass-Epoxy (NP500A / NP510A / NP511); Durostone®NEMA LI 1 grades | Glass-epoxy laminate | Carries load; CTI-rated creepage duty | NEMA LI 1 designations; D149 methods per TDS | Supports, extenders, rigid barriers | |
| Muscovite & Phlogopite Mica SheetRigid / flexible grades | Mica paper laminate | Inorganic; stable at fault temperatures | Per maker TDS; supports programs framed by NFPA 70E / IEEE 1584 (by designation) | Arc-adjacent barriers, hot locations | |
| ManniGlas® Glass-Fiber Paper (1200–2000)Glass-fiber designations | Inorganic glass-fiber paper | Temperature endurance per grade TDS | Per maker TDS, method named per grade | Hot-spot layers, arc-adjacent barriers | |
| PORON® 4701 Series + Mica Fire-Barrier Sheet (BBU set)BBU shelf pair | Microcellular PU + mica laminate | Compression window + barrier tier | ASTM D3574; UL 94 V-0 (40V0 TDS); supports UL 1973-evaluated designs (by designation) | BBU shelf pads & barrier layers | |
3. Creepage & clearance / dielectric-withstand planner
Enter the working voltage, the pollution degree, and the insulation material group by CTI, and the planner returns the required creepage (the surface path a tracking fault must travel) and required clearance (the shortest path through air), framed by IEC 60664-1 insulation-coordination practice. Add an insulation thickness and the grade's dielectric strength from the TDS and it also shows the dielectric-withstand margin across that layer.
The cross-section on the right annotates each computed distance live. This is a first-order planning estimate to validate in the application; the insulation-coordination analysis itself stays with the equipment designer, and per-grade CTI and dielectric strength come off the maker TDS.
At 600 V RMS, pollution degree 2, material group II, IEC 60664-1 practice points to about 3.16 mm of creepage (3.0 mm class) and 1.49 mm of clearance. A 0.25 mm dielectric at 20 kV/mm withstands about 5.00 kV — well over the 0.85 kV peak working stress, so the layer is thickness-driven by handling and margin, not by breakdown.
Creepage (blue, over the surface) is the path a tracking fault crawls; clearance (navy dashed, through air) is the shortest gap; the dielectric thickness is the through-barrier dimension the withstand uses. Distances are drawn to relative scale.
Skip ahead and request your engineering review now
If your drawing set already calls out a film gauge, an aramid designation, a laminate grade, or a folded barrier flat pattern, send it over for engineering review against the TDSs and the standards language.
Material reference
Detailed notes for the families referenced on this page: the films and papers (Kapton® polyimide, Nomex® aramid, flame-rated polypropylene barrier stock, and the family-level fish paper and PET films), the laminates (G10/FR4, G11, Durostone®), the inorganics (mica sheet, ManniGlas® glass-fiber paper), and the BBU shelf set (PORON® with mica fire-barrier sheet).
Values are per the maker TDS on file for each grade with the method named; system, equipment, and facility standards are cited by designation only, with the evaluation belonging to the customer's tested design.
H-O die-cuts, kiss-cuts, slits, scores, and kits every family to drawing.
Kapton® HN / FN Polyimide FilmBusbar wrap, liners, bonded wraps · thin-gauge designations · dielectric methods per maker TDS
Specify gauge, wrap geometry, and any heat-seal need. Die-cut edges replace field trimming, which is where most wrap failures start.
Nomex® Aramid Insulation Paper (410 / 414 / 818 Aramid-Mica)Slot & layer insulation, barriers, joint covers · thermal-class context per IEC 60085 framing on the TDS
Specify designation, thickness, and slit-width tolerance. The full voltage-range version of this family's story lives on the busbar, transformer & motor insulation sibling page.
Flame-Rated Polypropylene Barrier Stock (Formex™-Class Family)Folded phase & section barriers · UL 94 classes and CTI per vendor TDS · cited by family designation
Converted at the family level; properties per the vendor TDS for the selected grade. Where the barrier sits near heat, the aramid family above takes over; final material selection should be validated in the application.
Vulcanized Fibre (Fish Paper) & PET Dielectric Film (Family Level)Economical liners, covers & spacers · converted at the family level per vendor TDS
Commonly used for cost-driven liner duty; may be suitable depending on temperature and stress. Final material selection should be validated in the application.
G10/FR4 & G11 Glass-Epoxy Laminate (NP500A / NP510A / NP511) + Durostone® CompositeSupports, standoffs, creepage extenders · NEMA LI 1 grade designations
Specify grade designation, thickness, fastener loads, and working temperature. G11 steps in where the plant's hot spots crowd the FR4 ceiling; Durostone® where the part is frankly structural.
Muscovite & Phlogopite Mica Sheet (Rigid / Flexible)Arc-adjacent barriers, hot locations, BBU fire-barrier duty · inorganic
Edges, tabs, and tolerances come off the drawing, not the shear; a barrier earns its keep only if it covers the footprint and survives assembly handling.
- Muscovite rigid sheet (505 series)rigid muscovite plate, grades 505.2–505.4 / 505.2P–505.3P, 0.1–1.5 mm
- Muscovite rigid sheet FR / arc-ratedrigid muscovite plate for arc-exposed positions
- Muscovite flexible sheet (Cogemicanite 132-2)flexible muscovite sheet, retains properties to 500 °C
- Phlogopite rigid sheet (700 °C continuous)grades P / PC, 700 °C continuous, 1000 °C intermittent
- Phlogopite flexible sheet (132-1P)flexible phlogopite sheet for curved barriers
- Mica fire barrier sheet – Standardrigid mica fire-barrier plate
- Mica fire barrier sheet – Shield T classcompressible-core mica fire and thermal barrier sandwich
ManniGlas® Glass-Fiber Insulation Paper (1200 / 1900 / 1902 / 2000)Hot-spot layers & arc-adjacent barriers · inorganic glass-fiber paper
Specify grade and thickness; per-grade temperature data lives on the maker TDS with the method named.
PORON® 4701 Series + Mica Fire-Barrier Sheet (BBU Shelf Set)BBU cell pads & barrier layers · ASTM D3574 methods · V-0 class on the 40V0 TDS
Send the cell maker's preload window in kPa and the swell allowance; firmness grade and thickness fall out of those two numbers.
Telecom power insulation: engineer-grade FAQ
Ten of the questions we hear most from telecom power-plant, rectifier, and BBU equipment teams. If your question isn't here, send a drawing or call, engineering picks up.
Are these insulation materials UL-listed for telecom power equipment?
Equipment listings belong to the tested equipment, not to the materials inside it. What the materials on this page carry is their own documentation: flammability classes such as UL 94 V-0 on the listed grade TDSs, dielectric data with the method named, and lot-code traceability. They support equipment designs evaluated to the customer's standards program, with system, equipment, and facility standards (IEC 60664, UL 1973, NFPA 70E) cited by designation.
H-O supplies converted layers and paperwork as an ISO 9001:2015 certified organization; the equipment designer owns the evaluation. [3]
What insulates a −48 VDC busbar in a telecom power plant?
Three materials split the duty by mechanics: Kapton® polyimide film where the insulation bends and wraps the bus, aramid paper (Nomex®) where a tough conformable sheet covers a joint, and G10/FR4 glass-epoxy laminate where the insulation also carries load as supports and standoffs. At −48 VDC the spacing margins are usually mechanical rather than electrical, and the plant-practice driver is fault current and dropped-tool protection rather than dielectric stress. [1]
What is a phase barrier in a rectifier or PDU, and what is it made of?
A die-cut, scored insulating sheet that folds into a channel, box, or cover at assembly, separating input phases, AC from DC sections, and field-wiring lugs from everything else. The folding workhorse is flame-rated polypropylene barrier stock in the Formex™-class family, with UL 94 classes and CTI data per the vendor TDS; aramid paper takes over near heat, and FR4 plate handles spans that must stay rigid. [3]
Flame-rated polypropylene vs aramid paper vs glass-epoxy: how do I choose a barrier material?
By temperature and mechanics. Flame-rated polypropylene folds into self-supporting shapes and is the economical default at modest working temperatures. Aramid paper holds its properties near heat (thermal-class context per IEC 60085 framing on the maker TDS) and folds well but does not hold a crease as crisply. Glass-epoxy laminate is rigid, carries fastener loads, and serves where the barrier doubles as structure. Each family's flammability class and CTI come off its own TDS; final material selection should be validated in the application. [5]
How do creepage and clearance extenders work at low DC voltage?
They lengthen the surface path between conductors so the equipment design can meet its required creepage in a geometry that has run out of air. The equipment design's IEC 60664 insulation-coordination practice sets the required distances from working voltage, pollution degree, and material group; a barrier plate or channel with strong tracking resistance (CTI per the maker TDS) makes those numbers achievable. At −48 VDC, pollution degree in OSP and central-office air is typically the driving variable. [1]
What goes inside a BBU shelf for insulation and cushioning?
Typically three layers: PORON® microcellular urethane pads that hold cells in their compression window (specified by compression-force-deflection per ASTM D3574; the 4701-40V0 grade carries a UL 94 V-0 class per its TDS), Kapton® film as dielectric wrap and tray liner, and, in lithium designs, a mica fire-barrier layer at the cell footprint supporting the system's thermal-runaway strategy. UL 1973 evaluates the battery system; the listing belongs to the tested assembly. [6]
Can a barrier be "arc-rated"?
Not in the way a drawing note sometimes implies. Arc-flash programs are framed by NFPA 70E workplace practice and IEEE 1584 study methods at the facility level, and arc ratings attach to tested equipment and PPE, not to converted sheet materials. What a mica or glass-fiber barrier carries is its own TDS-documented behavior: inorganic chemistry that does not melt or contribute fuel at fault temperatures. Write the program standards by designation and the material properties per TDS, and the documentation review goes smoothly. [7]
What thickness of Kapton or Nomex do I specify for slot and layer insulation?
Off the winding drawing, not a rule of thumb: slot geometry, winding process, and the insulation system's thermal class set the designation and thickness, and the maker TDS carries the dielectric data per gauge with the method named (ASTM D149 class). What H-O needs is the designation, thickness, slit-width tolerance, and any heat-seal requirement; if those are still open, send the winding drawing and the review proposes them. [2]
Does H-O supply materials with UL 94 V-0 ratings?
Yes, materials are available with UL 94 V-0 ratings per the vendor TDS: the flame-rated polypropylene barrier grades, PORON® 4701-40V0, and other listed grades across the families on this page. The class belongs to the listed material grade per its TDS; H-O converts the material and supplies the documentation, and does not independently certify materials. Name the required class on the drawing and the review confirms the grade carrying it. [3]
What should I put on the drawing set so the quote comes back right the first time?
By job: for busbar work, the cross-section, bend radii, and wrap geometry; for barriers, the flat pattern with fold and score lines plus the flammability class; for magnetics, the winding drawing with designations and slit tolerances; for extenders, the geometry, grade, and required creepage note; for BBU shelves, the cell footprint, preload window, and barrier-tier strategy; for arc-adjacent parts, geometry, thickness, and the program context by designation.
Plus quantities for prototype and production. "Recommend the family" is a valid callout: that is what the engineering review is for.
Glossary: terms used on this page
Quick reference for the DC-plant, insulation, and standards terminology used throughout. Each entry links to the relevant standard or test method where applicable.
−48 VDC plant
The classic telecom DC power architecture: rectifiers convert utility AC to a nominal −48 VDC bus (positive grounded), with battery strings floating on the bus for backup. Low voltage, high current, and high available fault current define its insulation problems.
BBU (battery backup unit)
A rack- or shelf-mounted battery module that backs the DC plant or an individual shelf. Lithium BBU designs bring the battery-module material stack with them: compression pads, dielectric wrap, and barrier layers supporting designs evaluated to UL 1973 [6] at the system level.
Phase barrier
An insulating sheet separating phases, sections, or field-wiring terminations inside power equipment. In telecom gear it is typically a die-cut, scored flat pattern that folds into a self-supporting channel or box at assembly.
Creepage distance
The shortest path between two conductors along an insulating surface. Required creepage grows with working voltage, pollution degree, and material group per the equipment design's IEC 60664 [1] practice; extender plates and channels lengthen the path where the layout cannot.
Clearance
The shortest distance between two conductors through air. Barriers placed between conductors force the air path around them, which is how a plate buys clearance in a crowded shelf.
CTI (comparative tracking index)
A measure of an insulating material's resistance to surface tracking under contamination, reported on the maker TDS. CTI assigns the material group used in IEC 60664-based spacing tables: better tracking resistance permits shorter creepage for the same conditions.
IEC 60664 (by designation)
Insulation coordination for equipment within low-voltage systems: the framework that sets creepage and clearance from working voltage, pollution degree, overvoltage category, and material group, per [1]. It governs the equipment design; the materials on this page are what those decisions get built from.
NEMA LI 1 / G10 / FR4 / G11
The industrial-laminate classification defining the glass-epoxy grades, per [4]. FR4 adds a flammability class to the G10 construction; G11 holds its mechanical properties at higher temperature. Specified by grade designation on the drawing.
UL 94 (per the grade TDS)
The flammability classification for plastic materials (HB, V-2, V-1, V-0, 5V classes), per [3]. The class belongs to the listed material grade per its TDS at the tested thickness; it is a material property, not an equipment listing.
Thermal class (IEC 60085 context)
The temperature classification framework for electrical insulation systems referenced on insulation TDSs, per [5]. The class attaches to the evaluated insulation system; individual material TDSs cite their thermal context within it.
Dielectric breakdown (ASTM D149 class methods)
The voltage at which an insulating material fails under test, reported per ASTM D149-class methods [2] on the maker TDS, per gauge. A laboratory value measured under defined conditions, not a service rating.
Arc-flash program (by designation)
The facility-level electrical-safety framework built on NFPA 70E [7] workplace practice and IEEE 1584 [8] study methods. Barrier materials are converted ingredients inside that program; the study, labeling, and ratings belong to the facility and its tested equipment.
Telcordia GR-3108 (by designation)
Generic requirements for network equipment in the outside plant, with its operating-class framework. Cited here by designation as design context for OSP-deployed power and BBU equipment; the evaluation belongs to the equipment maker's tested design.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, and maker technical data sheets cited throughout this page. System, equipment, and facility standards are cited by designation: they evaluate designs, systems, and programs, and the evaluation belongs to the customer's tested design. Standards editions current as of June 2026; verify against the publishing body before final spec. H-O converts materials tested to the material-level methods on the source maker's TDS; H-O does not certify systems or independently certify materials unless explicitly stated on the quote.
[1] IEC 60664 (by designation)
Insulation coordination for equipment within low-voltage supply systems: the framework behind creepage, clearance, pollution degree, and material-group decisions in the equipment design. Cited by designation; the analysis belongs to the equipment designer. webstore.iec.ch (IEC 60664-1)
[2] ASTM D149
Standard test method for dielectric breakdown voltage and dielectric strength of solid electrical insulating materials at commercial power frequencies. The method behind the dielectric values on the film, paper, and laminate TDSs cited on this page. store.astm.org (ASTM D149-25)
[3] UL 94 (per the grade TDS)
Standard for tests for flammability of plastic materials for parts in devices and appliances. Classes (HB through V-0 and 5V) attach to the listed material grade at the tested thickness per the maker TDS; they are material properties, not equipment listings. ul.com/services/combustion-fire-tests-plastics
[4] NEMA LI 1 (by designation)
NEMA standards publication for industrial laminating thermosetting products: the grade-designation system (G10, FR4, G11, and related grades) used to specify the glass-epoxy laminates on this page. Cited by designation, by name only.
[5] IEC 60085 (by designation)
Electrical insulation: thermal evaluation and designation. The thermal-class framework referenced on aramid and film insulation TDSs; the class attaches to the evaluated insulation system. webstore.iec.ch (IEC 60085)
[6] UL 1973 (by designation)
Standard for batteries for use in stationary and motive auxiliary power applications: the battery-system standard behind lithium BBU shelves. Evaluated on the system; cited here by designation, with the listing belonging to the tested assembly. shopulstandards.com (UL 1973)
[7] NFPA 70E (by designation)
Standard for electrical safety in the workplace: the facility-level practice that frames live-work boundaries and the barrier hardware around them. Cited by designation as program context; the program belongs to the facility. nfpa.org (NFPA 70E)
[8] IEEE 1584 (by designation)
IEEE guide for performing arc-flash hazard calculations: the study method behind facility arc-flash analyses. Cited by designation as the analytical context for arc-adjacent barrier placement. standards.ieee.org (IEEE 1584-2018)
Updated . Standards editions and links current at publication; verify against the publishing body before final spec. H-O converts materials tested to the methods cited; H-O does not certify systems. Lot-specific documentation available on request.
Get a telecom power insulation engineering quote
Send a drawing set, flat pattern, or winding drawing. We typically respond within one business day with a material recommendation, prototype lead time, and TDS verification against your flammability classes, dielectric requirements, and standards language.
See also: related H-O application pages
Engineering content for the adjacent power-insulation sub-applications, the parent application, and the owning industry hub. Each page covers material selection, failure modes, and converter-side process detail for its application family.
Sibling sub-application
Busbar, transformer & motor insulation
The full laminate, mica, aramid, and film story this page's plant jobs draw from, across the voltage range.
Read the page
Sibling sub-application
Telecom & data center EMI shielding
Board-level and enclosure EMI gaskets, fingerstock backers, and absorbers for telecom and data-center hardware.
Read the page
Sibling sub-application
5G & small cell infrastructure
Compact thermal, sealing, and EMI parts sized for pole- and wall-mounted 5G small-cell radios.
Read the page
Sibling sub-application
Power electronics & drive insulation
The dielectric-and-TIM playbook inside rectifier modules and converters, at drive and inverter scale.
Read the page
Sibling sub-application
Data center power & UPS systems
The stationary-battery deep dive behind this page's BBU section: Li-ion UPS stacks, 48 V rack power, and generator rooms.
Read the page
Sibling sub-application
Arc flash & fire protection
The dedicated treatment of mica, glass-fiber, and fire-barrier families this page's Job 6 places in the telecom power room.
Read the page
Industry hub
Telecom & data centers
The full telecom and data-center application family: thermal, EMI, sealing, power insulation, and protection.
Read the page
Parent application
Energy, power & high voltage
The cross-industry power overview: insulation systems, creepage logic, and the material catalog this page's jobs draw from.
Read the page
Send the drawing set for your −48 V plant insulation
Wraps, barriers, liners, extenders, and BBU kits, in Winsted, Connecticut with material traceability and lot-code TDS records. Typical response in one business day.
Material data & standards. All dielectric, thermal, compression, and flammability values on this page are taken from the source maker's technical data sheets with the method named (ASTM D149-class dielectric methods, ASTM D3574 cellular methods, UL 94 classes per the listed grade TDSs, NEMA LI 1 grade designations).
System, equipment, and facility standards (IEC 60664, IEC 60085, UL 1973, Telcordia GR-3108, NFPA 70E, IEEE 1584) are cited by designation only: they evaluate designs, systems, and programs, the evaluation belongs to the customer's tested design, and the materials on this page support designs evaluated to them.
Performance depends on grade, geometry, compression, adhesive system, and environment; final material selection should be validated in the application. H-O converts materials; H-O does not design power plants, perform insulation coordination, conduct arc-flash studies, or certify systems, and does not independently certify materials against the standards unless explicitly stated on the quote. Verify against the maker TDS and your equipment-level evaluation plan.
Conversion scope. H-O and converts sheet, roll, and laminate stock to drawing in Winsted, Connecticut: die-cut and scored barrier flat patterns, slit films and papers, waterjet-cut thick laminate sections, laminations, and kitted insulation sets, with material traceability and lot-code TDS records. H-O does not mold or extrude in-house; molded or extruded profiles are coordinated through a partner network. Lead-time and MOQ details are in the quote form above. Renderings and diagrams on this page are representative illustrations, not product photographs.