Underfusing

[Michael J. Merino]

Is there anything wrong with underfusing? I know for A/C systems this is done for the surge, but what about for other applications? I am talking about a breaker that is to small for the wire it protects. I saw an 8 stranded copper on a 15 amp breaker. It feeds the electric start for the gas range.

[David P. Valley]

8 stranded?

What size wire was it? A breaker only accepts a limited amount of wire.

If a breaker is too small for the wire it protects, a nuisance tripping will occur if it becomes a problem.

[Michael J. Merino]

8 stranded = 8 gauge. Sorry

[Frank P. Newman]

Except for the problem of nusience tripping already mentioned, I don't really feel that there is any such thing as "underfused". The wire really doesn't care if it is being protected at less than it's rating.

[Larry D. Kage]

Originally Posted by mmerino

It feeds the electric start for the gas range.

Probably had an electric cook top before...

[jkogel]

I ran into this the other day, the original 40 amp circuit had been downgraded to 15 amp to run a small heater. As long as the larger wire fits the breaker without needing to be whittled down, no problem. Explaining this to my client, was a bit hard.

John Kogel
www.allsafehome.ca

[wsiegel]

except that that wire may be too big for the breaker. how was it attached?

[Terry Clayton]

you mentioned dropping the fuse size for A/C, normally if they change the size it is to allow for the start up current draw and it is allowed to increase the fuse/breaker to accommodate this. smaller fuse/breaker would prevent the wire from being overloaded

[Paul W. Abernathy]

Many times this is done for voltage drop. As long as the termination is designed to handle the size conductor being placed on it, if the person chooses to run a 8 AWG to a 15 or 20A breaker then thats a design choice....and as long as the conductor and equipment is protected at is listing....does not matter.

I happen to look at a few breakers sitting here on my desk...an Classified Breaker and a homeline 15A and they both said 14-8 AWG are allowed with a single termination...so it depands on the breaker and it will list it on the label....check those labels fella's as this is not a rule of thumb issue....its a labeling issue.

[Michael J. Merino]

Originally Posted by pabernathy

Many times this is done for voltage drop. As long as the termination is designed to handle the size conductor being placed on it, if the person chooses to run a 8 AWG to a 15 or 20A breaker then thats a design choice....and as long as the conductor and equipment is protected at is listing....does not matter.

I happen to look at a few breakers sitting here on my desk...an Classified Breaker and a homeline 15A and they both said 14-8 AWG are allowed with a single termination...so it depands on the breaker and it will list it on the label....check those labels fella's as this is not a rule of thumb issue....its a labeling issue.

Paul, I understand what your saying about the breaker being able to accept that size wire. But, what about the breaker being able to accept the amount of electricity? What if the 8 AWG is carrying 40 amps? Is nuisance trips the only issue? How is the condustor or equipment protected?

[Paul W. Abernathy]

You are reading WAY too much into the example.....if the load is 20A and the breaker is protected at 20A.......it would not matter if the wire was rated for 50A.....as long as the wire can handle the load and the circuit is protected accordingly based on the equipment rating ( which may say it needs a 20A OCPD )...having a larger conductor does not harm anything as long as the terminals can handle the size properly.

[Paul W. Abernathy]

Let me give you a better example.....( assuming the lugs are rated for the example ) can I have 4/0 CU on a 200A Breaker?...Sure I can, even if really I only needed 3/0CU ( commercial example )...point is as long as the conductor is sized to handle the load it can be used.

in the example above...I could have 500 CU kcMil if I wanted as long as the lugs to which the conductors are going to terminate allow it.

[Michael J. Merino]

Paul, I understand exactly what you are saying. As home inspectors we will not always know what the conductor services. If I know the 8 AWG conductor services a 10 amp appliance and is connected to a 15 amp breaker I am not going to be concerned.

But in the instance that there is no way of telling what the conductor services, is where I am concerned. If you do not know what the conductor services, you would report it to be corrected. Right?

[Paul W. Abernathy]

No I agree not all HI's will. However, those that have the training and are checking the proper labeling, the nameplates and knowing the conductor sizes will be able to make a determination upon their inspection.

None of my statements reflect "WHAT AN HI" should do, they reflect better understanding into the question you asked only and not what should be done by inspectors during inspections.

If you are asking can you have a 8 AWG ( provided the terminals allow it ) on a 15A breaker...most certainly, is it a hazard most certainly not. Will it require a HI to be sharp and on his/her game...most certainly and if you are asking what a HI should do if they can't determine it....by all means put it in the report as I have said a million times...better to defer liability in the event you just don't know.

[Michael J. Merino]

Paul, thanks for your help. I have a better understanding now. I will be more diligent for this in the future.