RHH Wire
RHH stands for Rubber High Heat-resistant. Dry locations, often triple-rated RHH/RHW-2/USE-2
Dry rating90°C
Voltage600V
Locationsdry
Specifications
| Property | Value |
|---|---|
| Full name | Rubber High Heat-resistant |
| Insulation material | XLPE (qualifies as rubber) |
| Outer covering | Optional moisture-resistant covering |
| Temperature rating (dry) | 90°C (194°F) |
| Voltage rating | 600V |
| Approved locations | dry |
When to use RHH wire
Dry locations, often triple-rated RHH/RHW-2/USE-2
Common applications for RHH:
- Specialized applications - RHH is used where its specific temperature and environment ratings are required
- See manufacturer specifications for approved installation methods
NEC code references for RHH
The NEC defines wire insulation types in Table 310.4(1) (formerly Table 310.104(A)). Key sections that apply:
- Table 310.4(1) - lists RHH with its temperature rating, insulation material, and approved locations
- Table 310.16 - ampacity values for conductors in raceway, cable, or earth (the values shown in our ampacity table above)
- Section 110.14(C) - termination temperature limits that determine real-world usable ampacity
- Section 310.15(C)(1) - adjustment factors for more than 3 current-carrying conductors in a raceway
Frequently asked questions about RHH wire
Where can I use RHH wire?
RHH is approved for use in dry per NEC Table 310.4(1). It has a dry temperature rating of 90°C. Always verify that your specific installation meets the approved location requirements.
What is the temperature rating of RHH?
RHH is rated 90°C in dry locations. The ampacity values in NEC Table 310.16 use the 90°C column for conductors rated at or above 90°C, but actual usable ampacity is limited by the termination temperature (typically 75°C per 110.14(C)).
Other wire insulation types
THHN 90°CTHWN 75°CTHWN-2 90°CXHHW 90°CXHHW-2 90°CRHW-2 90°CUSE-2TW 60°CNM-B 60°CUF-B 60°CMC Cable 90°CAC Cable (BX) 90°CSER/SEU 75°CPV Wire 90°CTHHW 90°CTHW 75°CTHW-2 90°CRHW 75°CMI 90°CUF 60°CXHH 90°CFEP 90°CSIS 90°C
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Important: For reference only. Not a substitute for a licensed electrician. Electrical work can cause serious injury, death, fire, or property damage if performed incorrectly. Always hire a licensed electrician for electrical work, especially for service upgrades, panel work, and 240V circuits. Values are derived from NFPA 70 (NEC) for educational purposes. Always verify against your locally adopted NEC edition and amendments - local jurisdictions may enforce stricter requirements. WireRef provides reference information only and is not responsible for work performed based on this content. NEC® is a registered trademark of the National Fire Protection Association. Free NEC access via NFPA · OSHA Electrical Safety · Terms of use.
NEC 2023 references verified April 2026