Can you use too big a wire for a subpanel?

[atgcpaul]

The electrician wants to use 6-3 wire + ground for a new 60amp 220V subpanel.
No argument there. My dad has cable of unknown wire number and gauge he
used for his cabin. He says it's sized to power 200A service for his cabin.
So this cable has to exceed what's needed for my sub.

The wire going to my garage is going underground in a conduit. Can I use my
dad's extra cable for my sub? It's not possible to have too thick a wire is it
as long as it fits the lugs in the sub?


Thanks, Paul

[Tom Slick]

I would think as long as it fits in the lugs it should be ok. if it were too big it would be mechanical reasons not electrical.

[paintandbodtman]

wire guage

Not a electrician but I would think that using too large a wire gage in this instance would be the same as replacing a fuse with a higher rating than whats supposed to be used. If you have a fire and an insurance claim the investigator could possibly deny claim if this subpanel is involved, lots of times insurance adjusters look for contributory neglegence. Just something to think about FWIW

Wayne

[LCHIEN]

Not a electrician but I would think that using too large a wire gage in this instance would be the same as replacing a fuse with a higher rating than whats supposed to be used. If you have a fire and an insurance claim the investigator could possibly deny claim if this subpanel is involved, lots of times insurance adjusters look for contributory neglegence. Just something to think about FWIW

Wayne

excepting where it won't fit the connnector and is left partially inserted, I can think of no reaons why a bigger than required wire can be considered a hazard. The Code I think requires only minimum wire sizes.

[Jeffrey Schronce]

Not a electrician but I would think that using too large a wire gage in this instance would be the same as replacing a fuse with a higher rating than whats supposed to be used. If you have a fire and an insurance claim the investigator could possibly deny claim if this subpanel is involved, lots of times insurance adjusters look for contributory neglegence. Just something to think about FWIW

Wayne

There is no such thing as an insureds contributory negligence in a property claim. Contributory negligence is a legal principle applied in a few states in our country toward liability only (usually auto). A claim such as outlined above could not be denied in any state. If the homeowner and non-compensated/non-professional friends did it there is no subrogation potential either. If a professional did this the property policy would respond with claim payment and subrogate damages against the contractor.

[maxparot]

Wire and cable gauge requirements are minimum code requirements.
In other words you can legally exceed the code requirements by using a wire that is heavier than the requirement.
Using fuses or breakers of higher values creates a safety issue because it may allow the wiring it is supposed to be protecting to be overloaded.

[LCHIEN]

Wire and cable gauge requirements are minimum code requirements.
In other words you can legally exceed the code requirements by using a wire that is heavier than the requirement.
Using fuses or breakers of higher values creates a safety issue because it may allow the wiring it is supposed to be protecting to be overloaded.

exactly!!!

[leehljp]

I would double check in advance to make sure it does fit the lug - before you get ready to install it. DAMHIKT

[LarryG]

Currently, the only real reason you wouldn't want to use wire larger than necessary is because you'd have to pay for it. As in, pay through the freakin' nose. When I put the new subpanel in my shop a little over two years ago, I paid on the order of $32 for a 250' roll of 12/2 with ground. Today, the same roll costs somewhere north of $100. OUCH!!!

[atgcpaul]

Currently, the only real reason you wouldn't want to use wire larger than necessary is because you'd have to pay for it. As in, pay through the freakin' nose. When I put the new subpanel in my shop a little over two years ago, I paid on the order of $32 for a 250' roll of 12/2 with ground. Today, the same roll costs somewhere north of $100. OUCH!!!

Well, hopefully my dad has enough cable for me and gives me a family discount.
That's why I'm considering this route. The electrician is charging me only for
time and I'm paying for materials. He told me for the length of wire and gauge I
need (70'), that could put me over $500-$600 JUST FOR WIRE!!! I was pretty
floored. That's, like, a new jointer!

Thanks for the responses,
Paul

[BigguyZ]

Currently, the only real reason you wouldn't want to use wire larger than necessary is because you'd have to pay for it. As in, pay through the freakin' nose. When I put the new subpanel in my shop a little over two years ago, I paid on the order of $32 for a 250' roll of 12/2 with ground. Today, the same roll costs somewhere north of $100. OUCH!!!

Yeah- I noticed the same thing. I bought a couple of spools of 12/2 NM and now I'm nearly out. Looking at the higher prices on wire makes me think that Gas prices are reasonable....

[leehljp]

Now I think I understand . . .

(Not intending to hijack this thread)
I caught the tail end of some CNN news a couple of days ago. One of the newscasters said "what a shame it was that some people have taken to stealing other people's outside AC unit for the metal". That is all that I heard.

Was it copper that they were talking about? Has copper gone that high?

[LarryG]

Was it copper that they were talking about? Has copper gone that high?

Respectively: probably, and yes.

I just pulled my receipt file. On 8 July 04, I bought a 250' roll of 12/2 Romex at Lowe's for $29.50, plus tax. Today, they're not showing this same item on the web site, however a 100' roll is $58.99 -- that's exactly twice as much as I paid, but for only 40% as much wire!

They do show a 250' roll of outdoor-rated 12/2 ... $124. This grade appears to average about 12% higher than indoor wiring, so that would make the same roll I bought 26 months ago for $29.50 cost somewhere around $110 today.

[Thom2]

Has copper gone that high?

Over the course of the past few months, I've heard of numbers nearing $4/lb for scrap on several occassions.

[TheRic]

Back on topic......

Paul, Where I see you will have trouble is in the main panel box. The breaker that will control the sub-panel may not be able to handle the larger size wire. The sub-panel will probably handle the wire.

If you have that large of a size of wire, put a larger size sub-panel in the garage. Then you have room to expand, can isolate your electric runs. The breaker in the main panel box would need to be larger to handle the larger sub-panel, and the larger breaker might be able to handle the larger size wire.

Remember if you are going to larger wire, you will probably need larger conduit. He probably told you 1" conduit, with 200A wire you would probably need about 1 1/2" or 2" conduit. Don't remember the number of the top of my head, but you get the ideal.

If your trenching all of this in, consider putting in an extra conduit that you can run wire thru later ( phone, cable, network, intercom, etc.)