1. Originally Posted by Smart \$
...
210.21(A) states "Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load." Minimum OCPD is 20A × 125% = 24A, rounded up to next standard size 25A.
...
Originally Posted by 2Broke2Sleep
Got it. I overlooked 210.21 Would 10 AWG (romex/thhn/thw) with a 25 amp breaker satisfy this installation? Or as I stated previously, a 20A breaker rated at 100% with 12AWG THW?
Ummm... meant that to be 210.20(A)

Yes to first question.

To use a 20A, 100%-rated breaker requires the entire enclosure (panel board, e.g.) to be rated for 100% operation. You will also discover as part of achieving that rating, you must use all 90°C-rated conductors.
Last edited by Smart \$; 03-26-17 at 02:22 AM.

2. Originally Posted by 2Broke2Sleep
Got it. I overlooked 210.21 Would 10 AWG (romex/thhn/thw) with a 25 amp breaker satisfy this installation? Or as I stated previously, a 20A breaker rated at 100% with 12AWG THW?
What is the load you are trying to supply?

3. Member
Join Date
Mar 2017
Location
Florida
Posts
58
Originally Posted by iwire
What is the load you are trying to supply?
Hypothetically a cord and plug stereo system attached to a 20 duplex....(obviously a violation in the case of a 25 amp OCPD)

4. Originally Posted by 2Broke2Sleep
Hypothetically a cord and plug stereo system attached to a 20 duplex....(obviously a violation in the case of a 25 amp OCPD)
Hmmm... a cord-and-plug-connected sound system that draws 20A continuous. Not possible unless all you play is pink noise at max volume for more than 3 hours at a time.

5. Originally Posted by 2Broke2Sleep
Hypothetically a cord and plug stereo system attached to a 20 duplex....(obviously a violation in the case of a 25 amp OCPD)
That was what I was getting at, I was not sure if you were aware a 25 OCPD can not be used with a 20 amp receptacle.

Beyond that I agree with smart\$

6. Originally Posted by Smart \$
unless all you play is pink noise at max volume for more than 3 hours at a time.

I used to hook up concert power a lot and while killing time sometimes I would put my amp clamp on the feeders during the show.

It would be all over the place, and the (Harmonic?) currents on the sound power feeder neutral would often equal to the ungrounded conductor currents.

(208Y/120 source and distribution)

When I provided a 300 KVA trailer mounted generator for the lighting feed to an outdoor show it was fun watching it bounce around on it's springs to the beat of the music due to the lighting load changing. This was back in the 90s so the lighting rigs were all 1,000 watt PAR cans.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•