Underfusing

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.

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.

8 stranded = 8 gauge. Sorry

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.:wink:

Probably had an electric cook top before…

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. :stuck_out_tongue:

John Kogel
www.allsafehome.ca

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

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

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?

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.

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.

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?

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.

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

The example of #8 on a 15 A breaker makes the point pretty clearly. Whille it looks a bit odd, if the breaker has not been tripping and has been in that service for some peroid of time, a reasonable person can assume that the actual load on the circuit does not exceed 15A. You can check the actual running load, if you are comfortable using a clamp on ammeter, but the status of the breaker is a pretty good indicator. However, the wire itself doesn’t care because is is well overprotected. All that said, if I saw it in a penale that had not other signicficant problems, I would probably not refer it.

In my former profession, Equipment Installation, at the TELCO, this was common place. Upsizing the wire decreases impediance and voltage drop at the other end. Ex. A 250’ Run of 2/0 wire, properly spliced(Burndey Hydraulic crimper) and terminated at both ends using a section of #6 wire, and only fused at 30A. The terminations of the 2/0 wire needed to be properly downsized to terminate at the Fuse Panel and far end correctly. While this example is extreme comparing to HI’ing, the point being, as already mentioned, that as long as the terminations of the wire are rated for the size and type of wire(ex. ALCU) at the breaker there should not be a need to defer it, call it out. I have seen this upsizing more frequently in a commercial environment that has much longer circut runs than in a residential environment.

Another example from a power utility, beyond the SOP and HI.
In this area of the country, If a home is more than 250’ away from it’s serving Power Co’s Transformer, they will run HV Distribution(varies~8KV) lines and usually place the serving step down transformer closer to the house. They do this because of the Voltagedrop, and not wanting to run a longer and larger more exspensive drop wire from the step down transformer to the meter. When Voltage drops due to a wire’s length and impediance, Amperage increases, requiring larger gauge conductors to carry the same amount of load over a greater distance.

When inspecting, I Check the size and type of the conductor, verify that the terminals are rated for such a termination. If I am not 100% verifiably sure and do not know, or I am unable to verify, or I suspect or notice an obvious safety concern, I will always defer it to a licensed electrician for further investigation/evaluation/repair. I would rather look like an idiot, than have clients lives, personal safety, and the liability placed on me by my unqualified opinion that can not be supported by verfiable facts and observations.

My reasoning being, most, if not all electrical panels are unique and different, and vary greatly upon when the panel was installed and by whom. I report what is there at the time of the inspection. I do see modifications, upgrades, additions, removals and repairs all the time. I give the client a report based on my observations and level of expertise.

The reason behind why I find a circut(s) underfused,
is not for me the HI to determine. It is my job to check for
obvious and future safety hazzards that may exist now or in the future. Like, you can not stuff a #8ga wire into a termination or terminal only designated and rated for a smaller #10 gauge wire.

Wait a minute, there are a lot of HI’s on here that want to quote “CODE” and determine if the place “CONFORMS” to thier wants.

I just do a simple SAFE & SANITARY inspection myself.

“If it ain’t broke don’t fix it”

I believe HI’s dont want to quote code…I do believe they need to know codes in order to understand the origin of many safety concerns. No one ever said to quote codes ( I don’t believe ) but knowing them puts you higher up on the knowledge food chain.
Understanding the WHY helps to better translate the HOW.

Define “sanitary”.

“Hospital Sanitary”?
“Restaurant Sanitary”?

Which health departments guidelines do you use for “sanitary”?