Special Marking for Motor Circuits

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paullmullen

Senior Member
Location
Wisconsin
Occupation
Electrical Engineer & Master Electrician
Because of the differences between start-up current and running current in motor circuits, it is common for the conductors to to be differently sized than might be implied by using T310.15(bB)(16) alone. A DIYer or other person following behind me might look at the 70A circuit breaker for the heat pump I'm installing and think... "oh cool, the conductors are sized for 70A" without actually checking to see that they're actually 8AWG THHN. They might just think "Ah, 70A breaker, that must be appropriate for a 70A continuous load" and misuse those conductors during a remodeling.

So here's my question: Do any of you mark motor circuits at the breaker panel in a special way to ensure that future modifiers don't make the mistake I've implied above? I'm worried about the guy that comes after me. Maybe I should just ignore that and move on.
 
paullmullen said:
So here's my question: Do any of you mark motor circuits at the breaker panel in a special way to ensure that future modifiers don't make the mistake I've implied above? I'm worried about the guy that comes after me. Maybe I should just ignore that and move on.
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Like Don said no. Any labeling used to keep an unqualified person from screwing something up in the future would be a waste of time.
 
augie47 said:
If they are not knowledgeable enough to figure out what's happening they shouldn't be in the panel.
Labeling the breaker as required should be enough
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I agree. I'm trying to think of a future scenario where this could even be a problem. :unsure:
 
infinity said:
I agree. I'm trying to think of a future scenario where this could even be a problem. :unsure:
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It is easy to think of potential future problems.
How about if the DIY just taps off your 70A motor circuit to a general purpose receptacle?

You cannot future proof your installations.
 
jim dungar said:
It is easy to think of potential future problems.
How about if the DIY just taps off your 70A motor circuit to a general purpose receptacle?

You cannot future proof your installations.
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How will a note in the panel stop him from doing that? That's my point it's a waste of time and energy.
 
paullmullen said:
A DIYer or other person following behind me might look at the 70A circuit breaker for the heat pump I'm installing and think... "oh cool, the conductors are sized for 70A" without actually checking to see that they're actually 8AWG THHN. They might just think "Ah, 70A breaker, that must be appropriate for a 70A continuous load" and misuse those conductors during a remodeling.
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So, now we're supposed to worry about what a DIYer or other unqualified person might do and try to prevent them from making a mistake? :ROFLMAO:

-Hal
 
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