100% or 125% breaker tripping

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hhsting

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1. Let’s say I have 100% breaker at 20A. Load is continuous and draws 16A and running for more than 3 hours. Would breaker trip?

2. Let’s say I have 125% breaker at 20A. Load drawn is 16A continuous will breaker trip?

3. Let’s say I have 125% breaker at 20A. Load is 16A non continuous will breaker trip?

4. Let’s say I have 100% breaker at 20A. Load is non continuous and draws 16A. Would breaker trip?


Not test questions been sizing panelboard calculation and was wondering.
 
hhsting said:
1. Let’s say I have 100% rated breaker at 20A. Load is continuous and draws 16A and running for more than 3 hours. Would breaker trip?

2. Let’s say I have 80% rated breaker at 20A. Load drawn is 16A continuous will breaker trip?

3. Let’s say I have 80% rated breaker at 20A. Load is 16A non continuous will breaker trip?

4. Let’s say I have 100% rated breaker at 20A. Load is non continuous and draws 16A. Would breaker trip?


Not test questions been sizing panelboard calculation and was wondering.
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Post #1 125% breaker should be 80% breaker. Change above. Added word rated. Now whoever respond might have to take look again
 
Answers are still all no.

Change 16A to 20A throughout and then #2 becomes "maybe, not guaranteed to trip or to not trip" but the others are still all no.

Cheers, Wayne
 
wwhitney said:
Answers are still all no.

Change 16A to 20A throughout and then #2 becomes "maybe, not guaranteed to trip or to not trip" but the others are still all no.

Cheers, Wayne
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I don’t get it #2, #3 and #1 is still no post #3? 16A continuous would be 20A #1, #2? And 20A 80% #3 would be 16A which is non continuous load?
 
Note you can't just put a 100% breaker anywhere. It needs to be in an approved enclosure, typically by itself I believe. Also IIRC there is no difference between a regular and 100% breaker, there have the same trip curve, but there is a suffix in the part number (at least for sq D). It's really just about heat/airflow and not having a bunch of other breakers packed next to it.

I have a panel board with 13 three pole 20's running 16 amps continuous and they get very warm but have never tripped. I have had breakers trip on 80% of their rating in very hot areas.
 
hhsting said:
1. Let’s say I have 100% breaker at 20A. Load is continuous and draws 16A and running for more than 3 hours. Would breaker trip?

2. Let’s say I have 125% breaker at 20A. Load drawn is 16A continuous will breaker trip?

3. Let’s say I have 125% breaker at 20A. Load is 16A non continuous will breaker trip?

4. Let’s say I have 100% breaker at 20A. Load is non continuous and draws 16A. Would breaker trip?


Not test questions been sizing panelboard calculation and was wondering.
Click to expand...
No to all unless the ambient temp where the cb is installed is well above spec for the cb.
 
petersonra said:
No to all unless the ambient temp where the cb is installed is well above spec for the cb.
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That’s along the lines of what I was thinking. They won’t trip with the given current flow as long as everything else is kosher.

High ambient, loose connection....other?
 
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