Electric Unit Heaters - SCCR
- Thread starter whiggins
- Start date
Liklely it's not there as it's not required.
The requirement I believe is covered by UL 1995 is required to include an SCCR on the nameplate with the following exceptions as noted in section 37.3 :
“Equipment intended for use in one-and two-family dwellings, cord-and-attachment plug connected equipment,
or equipment supplied from a branch circuit protected at 60 A or less is not required to be marked with a short-
circuit current rating.”
I would imagine that it is based on the fact that with it is not an issue on circuits with the smaller conductor size.
For an example, a circuit using 25 ft. #6 Cu would reduce a 50,000 available fault to less than 10,000
The requirement I believe is covered by UL 1995 is required to include an SCCR on the nameplate with the following exceptions as noted in section 37.3 :
“Equipment intended for use in one-and two-family dwellings, cord-and-attachment plug connected equipment,
or equipment supplied from a branch circuit protected at 60 A or less is not required to be marked with a short-
circuit current rating.”
I would imagine that it is based on the fact that with it is not an issue on circuits with the smaller conductor size.
For an example, a circuit using 25 ft. #6 Cu would reduce a 50,000 available fault to less than 10,000
mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
Augie47, I questioned what you wrote so I ran a calc in SKM, as follows:
Thank you for the prompt replies. If I understand correctly, the 60 A or less rules applies to space heating equipment, but does not apply to compressor/refrigeration units? I know the 60 A exception used to be in 440.4 and was removed.
It seems strange that control panels and refrigeration equipment require adherence to SCCR rules, but electric unit heaters do not. They have contactors, fuse holders, etc. just like other devices.
Thanks again.
It seems strange that control panels and refrigeration equipment require adherence to SCCR rules, but electric unit heaters do not. They have contactors, fuse holders, etc. just like other devices.
Thanks again.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
SCCR applies to devices that switch or control or protect (by switching). It doesn't apply to end USE devices like motors or heaters.
- Location
- Connecticut
- Occupation
- Engineer
Different voltage. You assumed 208V, mayanees assumed 480V.
The larger unit heaters have contactors, fuses, etc. to cycle and protect the heating elements. If I built an industrial control panel to cycle heating elements, I believe it would require an SCCR rating. If these devices are inside the heating unit it doesn't seem to apply. That I don't understand.
mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yes, that would be true.