SER/SEU Wire

Q: What is the temperature rating of SER/SEU?

SER/SEU is rated 75°C in dry locations and 75°C in wet 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)).

SER/SEU stands for Service Entrance Cable (Round/Unarmored). Service entrance from meter to panel, subpanel feeders. SER has separate EGC, SEU has concentric neutral.

Dry rating75°C

Wet rating75°C

Voltage600V

Locationsdry, damp, wet

Specifications

Property	Value
Full name	Service Entrance Cable (Round/Unarmored)
Insulation material	XHHW individual conductors
Outer covering	PVC outer jacket
Temperature rating (dry)	75°C (167°F)
Temperature rating (wet)	75°C (167°F)
Voltage rating	600V
Approved locations	dry, damp, wet

When to use SER/SEU wire

Service entrance from meter to panel, subpanel feeders. SER has separate EGC, SEU has concentric neutral.

Common applications for SER/SEU:

Specialized applications - SER/SEU is used where its specific temperature and environment ratings are required
See manufacturer specifications for approved installation methods

NEC code references for SER/SEU

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 SER/SEU 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 SER/SEU wire

Where can I use SER/SEU wire?

SER/SEU is approved for use in dry, damp, wet per NEC Table 310.4(1). It has a dry temperature rating of 75°C and a wet rating of 75°C. Always verify that your specific installation meets the approved location requirements.

What is the temperature rating of SER/SEU?

SER/SEU is rated 75°C in dry locations and 75°C in wet 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°C THWN 75°C THWN-2 90°C XHHW 90°C XHHW-2 90°C RHH 90°C RHW-2 90°C USE-2TW 60°C NM-B 60°C UF-B 60°C MC Cable 90°C AC Cable (BX) 90°C PV Wire 90°C THHW 90°C THW 75°C THW-2 90°C RHW 75°C MI 90°C UF 60°C XHH 90°C FEP 90°C SIS 90°C

Requirements vary by state. NEC edition, licensing, permits, and GFCI rules differ by jurisdiction. Check your state or pick it below for personalized info across WireRef.

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