Main breakers in sub panels

Need some clarification on sub panel breakers and possible undersized wires.

The 200 amp main service supplied a sub panel from a 40 amp breaker using #8 AWG. This # 8 AWG wire was connected to a 100 amp main breaker in the sub panel. Is this a situation where you would report an undersized wire attached to the 100 amp breaker or is it redundant as the 40 amp breaker in the main panel should prevent more the 40 amps running through the #8 AWG wire? If you need clarification please ask.

Awaiting your responses. Thanks all.

If it is within the same building then the 100A breaker at the remote distribution panel is simply a disconnect, In fact, it is not actually required but in many cases it is cheaper than a MLO panel so they install it. The conductors and panel are protected by the 40A OCPD at the source.

There could be a possible problem is if the 100 amp CB is not listed for use with a small #8 conductor.

Thank you Paul, that is what I thought but needed to be sure. Thanks to you also Robert.

Good point … but how significant that is for an HI is another story … :wink:

I’m not one so I cannot answer that. But given all that I’ve read on this forum about HI’s doing IR scans I would think that the use of the proper termination that matches the conductor size is somewhat important.

It is. :slight_smile:

The only thing I can see as being an issue is if the smaller wire is completely on one side of a large lug where a somewhat poor connection is possible.

I would make a note of the condition and check that it looks like a solid connection, but I just don’t see it a being a significant issue unless it was poorly installed.

JMO & 2-Nickels … :wink:

So if the 100 amp CB is clearly labeled as suitable for use with #6-#1/0 conductors you don’t see a problem with connecting a #8?

Things are not always that black or white for home inspectors … there are different shades of grey.

I indicated I would make a note of that as an issue. But if there is a solid connection, why would you consider that a significant issue or safety hazard (which for an HI would mean an immediate correction recommendation)?

Well there’s right and wrong according to the listing of the equipment. I’ve seen double taps that have been in panels for 20 years without any problems. Should a HI not report those either because they look good or have been there for a long time? Where do you draw the line?

Thats the black and white for electricians and AHJ’s … HI’s often have to make judgment calls as to how significant an issue is. I agree a small wire on a large breaker is likely an issue with the listing. I just don’t agree it’s a significant issue if there’s a solid connection.

How about a smaller wire on a larger breaker with a poor connection (say to one side of the lug) thats been there for 20 years without a problem. I would consider that a significant issue, because loads on circuits can change, and just like double lugs with wire-to-wire contact, there is a potential for a poor connection.

Thats a difficult call for HI’s on some issues.

Would be a listing violation. Being that I can’t see the breaker…I will leave that to the origional poster.

Yup, that was my point it could be. I’m assuming that an HI should note that in his report, yes or no?

Do you have pictures for the panel you inspected?

Most likely a listing violation, and would depend on the breaker listing and the (slim) possibility that the AHJ accepted that as an “alternate method” (been there, and got the tee shirt). Thats a slippery slope for an HI and why the term “violation” shouldn’t be in a home inspectors vocabulary.

Checking listing/labeling is beyond the HI Standards of Practice. But, yes it should be noted as a “concern” in the report if observed … possibly even a “defect” if poorly installed or showing signs of poor performance.

I would note it…however, I would not call it a violation of any codes in an HI report. Leave that up to the electrical contractor. If he has other issues he/she needs to look at they can look at that also…either way the HI is clean.