If your project crosses the border into Canada — or you’re specifying for a Canadian contractor — you’ll run into the RW family: RW75, RWU75, and RWU90. These are CSA C22.2 No.38 + UL44 single-core cables, 600V/1000V, XLPE insulation over bare copper (or aluminum) conductors. They look alike on a cut sheet, but the three letters after “RW” decide whether you can bury it, whether you can run 90°C in wet locations, and whether it belongs on a rooftop PV feeder.
This article breaks down the naming, the side-by-side differences, and which one goes on your BOQ.
Decoding the Name (CSA Convention)
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Letter
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Meaning
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|---|---|
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R
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Building wire (generic CSA prefix for single-core distribution)
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|
W
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Moisture / water resistant (wet-location rated)
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|
U
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Direct burial permitted (no sleeve required)
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75 / 90
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Maximum continuous operating temperature (°C)
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So the three tiers:
- RW75 = Wet-rated, 75°C dry & wet, no U → cannot direct-bury
- RWU75 = Wet-rated + U (direct burial), 75°C dry & wet
- RWU90 = Wet-rated + U (direct burial), 90°C dry & wet → top tier
All three share the same DNA: XLPE insulation, bare Cu/Al conductor, 600V/1000V, CSA C22.2 No.38 + UL44 listed.
Full Comparison Table
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Parameter
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RW75
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RWU75
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RWU90
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|---|---|---|---|
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Code meaning
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R=wire, W=wet 75°C, no U
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R=wire, W=wet 75°C, U=direct burial
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R=wire, W=wet 90°C, U=direct burial
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|
Dry rating
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75°C
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75°C
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90°C
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Wet rating
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75°C (unified)
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75°C (unified)
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90°C (unified)
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Direct burial
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No – conduit only
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Yes – U suffix
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Yes – U suffix
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XLPE formulation
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Standard moisture-resistant XLPE
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Burial-grade moisture XLPE
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Full-modified XLPE (high temp + water + UV/aging)
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|
Ampacity reference
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NEC/CSA 75°C column
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75°C column
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90°C column (dry & wet) – no de-rating
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Installation scope
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Dry/wet indoor conduit, tray; no sun, no burial
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Indoor wet + basement + outdoor (SUN RES) + burial
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All-scenario: indoor high temp, rooftop, trench, PV inverter outlet, wet industrial
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Typical use
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Residential indoor general wiring, dry machine rooms, budget indoor runs
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Conventional outdoor service drop, shallow burial, basements, legacy RHW replacement
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PV DC/AC feeders, rooftop exposed, heavy burial, high-temp industrial, new-build主力替代 RHW-2
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US equivalent
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≈ RHW (no burial)
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≈ RHW + USE composite
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≈ RHW-2 + USE-2 composite
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Cost positioning
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Economy indoor
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Mid
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Premium – but saves gauge vs 75°C tier
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Three Differences That Drive Specification
1. The “U” Suffix = Direct Burial Permission
This is the most visible split:
- RW75 (no U): Conduit-only. You cannot throw it in a trench, even sleeved in PVC — the CSA/UL marking doesn’t permit it. If the inspector sees RW75 in a direct-burial run, it’s a fail.
- RWU75 / RWU90 (U): Both are listed for direct burial without sleeve. The XLPE formulation includes anti-moisture/anti-burial additives. For residential service laterals or landscape feeders, this is the line that matters.
2. 75°C vs 90°C Wet = Ampacity & Gauge Impact
Even though all three carry “W” (wet-rated), only RWU90 holds 90°C in wet locations:
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Conductor (example)
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RW75 / RWU75 (75°C wet)
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RWU90 (90°C wet)
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|---|---|---|
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#6 AWG Cu
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~65A (75°C column)
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~75A (90°C column)
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|
#2 AWG Cu
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~115A
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~130A
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RWU90 lets you stay in the 90°C ampacity column everywhere — dry or wet, buried or tray. That can mean downsizing one gauge vs RWU75 on a long wet feeder, which pays back the unit-price premium quickly on large-kcmil runs.
3. RWU90 Is the “New-Project Default” — Here’s Why
RWU90 effectively bundles three capabilities into one SKU:
- 90°C dry / 90°C wet (no de-rating)
- Direct burial (U)
- SUN RES eligible for rooftop/outdoor exposed (confirm marking per reel)
That makes it the natural choice for:
- PV inverter AC output feeders (rooftop → combiner → utility tie-in, often 1000V)
- Rooftop HVAC / exhaust fans exposed to sun
- Industrial wet plants (wash-down, near process water)
- Service laterals buried residential/commercial
Legacy RW75 still shows up in indoor-only, budget-conscious residential quotes (think interior branch circuits, dry machine rooms). RWU75 sits in the middle — outdoor + burial but capped at 75°C, mostly seen in retrofit or lower-budget commercial. For anything new, RWU90 is the spec most EPCs land on.
Application Cheat-Sheet
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Scenario
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Recommended
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|---|---|
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Indoor residential branch, dry conduit only, budget
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RW75
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Shallow burial service lateral, non-critical temp
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RWU75
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PV inverter AC feeder, rooftop exposed (SUN RES)
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RWU90
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Industrial wet plant, wash-down, 90°C wet required
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RWU90
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Heavy-direct-burial commercial service (no sun)
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RWU90
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Cross-border project needing US + CA listing
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RWU90 (dual CSA+UL, maps to RHW-2+USE-2)
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RW Series vs US Equivalents (Cross-Border Note)
Since your audience buys both sides of the border, here’s the mapping that matters:
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CSA
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US Rough Equivalent
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Key Caveat
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|---|---|---|
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RW75
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RHW (UL44)
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Neither buries. RHW wet capped 75°C too.
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RWU75
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RHW + USE-2 (limited)
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USE-2 is normally 90°C, so RWU75 is the “75°C version” of that combo
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RWU90
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RHW-2 + USE-2
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Closest true cross. If the US spec says RHW-2 + USE-2, RWU90 is the CSA-side match
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Don’t swap RW75 for THHN/THWN — THHN is PVC+nylon (C22.2 No.75 / UL83), totally different insulation family. RW series is XLPE (C22.2 No.38 / UL44). Crossing those two is a common PO mistake on mixed-border jobs.
Frequently Asked Questions
Q: Is RWU90 the same as R90?
A: No. R90 (from your previous T90/R90 article) is dry-only XLPE, CSA C22.2 No.38, no W, no U — conduit-only, 90°C dry. RWU90 adds W (wet 90°C) + U (burial). R90 ≈ XHH (UL side); RWU90 ≈ RHW-2+USE-2. Very different permissions.
Q: Can RW75 be used outdoors in conduit?
A: Technically conduit outdoor is a wet location per NEC/CSA, and RW75 iswet-rated at 75°C, so it passes the wet check — but it’s not SUN RES, and if the conduit is above-ground/exposed you still want UV protection. For any outdoor exposed, RWU90 with SUN RES is safer. And RW75 still can’t be buried.
Q: Does RWU90 need SUN RES for rooftop PV?
A: Yes. The “U” gives you burial permission, not UV. For rooftop/exposed tray, the jacket must carry SUN RES marking. Most RWU90 SKUs offer this — confirm with the cut sheet before the PV inspector walks the roof.
Q: Aluminum conductor available?
A: Yes, all three (RW75 / RWU75 / RWU90) are commonly stocked in AA8000-series aluminum for large kcmil feeders (service entrances, commercial mains). Same XLPE insulation, 90°C/75°C rules apply per conductor type. JZD stocks both Cu and Al.
Why Source RW75 / RWU75 / RWU90 from Jianzhenda Cable?
At JZD Cable (jzdcable.com), we manufacture the full RW family under CSA C22.2 No.38 + UL44 dual listing:
- RW75 – economy indoor wet/dry 75°C
- RWU75 – burial-capable, 75°C wet
- RWU90 – flagship, 90°C dry/wet, burial, SUN RES available, 1000V PV-grade
Cu & AA8000 Al, 14 AWG through 750 kcmil, black / colour IDs, custom reel lengths, full mill test + CSA/UL traceability. We also cross-reference to the US side (RHW, RHW-2, USE-2, XHHW-2) for mixed-border projects so your BOQ doesn’t fracture across two standards.
Need a CSA RW-series quote or a cross-border equivalency check?
Visit jzdcable.com— send gauge, Cu/Al, voltage (600V or 1000V), SUN RES / FT4 / burial requirement, and we’ll turn it in 24 h.
