# How do you tell if you have 60 amp or 100 amp service?

• posted on May 29, 2008, 5:59 am
How do you tell if you have 60 amp or 100 amp service?
The wiring in the service cable is aluminum. What sizes would be 60 amp and what would be 100 amp?
I have an old size fusebox, with main on the left side and range on the right side. While right now there are 4 of the long 60 amp fuses in the fuse box, am I correct that probably the correct numbers should be 60 amp in the main and 40 amp in the range for a total of 100 amps--and that this is probably a 100 amp service?
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• posted on May 29, 2008, 10:03 am

My guess (non professional) is 60A.

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• posted on May 29, 2008, 10:48 am

You are correct. The service entrance cable will determine the service size. If it is aluminum, it should be #2, if it's copper #4. Anything smaller would be a 60 amp service

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• posted on May 29, 2008, 4:12 pm

What is the diameter of #2 aluminum?
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• posted on May 29, 2008, 4:32 pm

theres a chance of a miss match, like a undersized meter socket.......
my bet 60 amps....
might as well upgrade once to 200 amps........

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• posted on May 29, 2008, 6:20 pm

How do you tell what size it is?
I have a 200 amp Sangamo meter. Would that still fit if it were an undersized meter socket?
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• posted on May 29, 2008, 6:55 pm
Jonathan Grobe wrote:

#2 wire is about 0.097" diameter.
Sounds like a "main and range" panel with both "main" and "range" being service disconnects (the range circuit will still be hot if you pull out the "main" fuses). I believe these all had a rating of 100A. You can use 60A fuses in both the "main" and "range" (but you may want to limit the range to 40). (If a calculation of the proper size of the service for the house is 100A the fuses can all be 60A.)
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• posted on May 29, 2008, 7:31 pm
Do electric companies always know what service you have?
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• posted on May 29, 2008, 8:19 pm

No, they don't. They only know how much you use. They may have a record of the size meter you have, but any newer installation would use a 4 or 5 jaw meter good for 200 amps. I don't know, offhand the circular mils of a #2 aluminum conductor, but even if you had that info, it probably won't help. The cable should have the numbers written on it's sheath. It would say something like 2-2-4 al

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• posted on May 29, 2008, 9:42 pm
bud-- wrote:

Huh?
You'd better at least consider the size of the wire downstream of the breaker before making such claims.
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• posted on May 30, 2008, 8:37 pm
bud-- wrote:

Oops, read the wrong column. #2 wire (conductor - stranded) is about 0.292" diameter. This is reasonable compared to dpb's value of "roughly 0.25" which may be solid wire.
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• posted on May 29, 2008, 9:15 pm
Jonathan Grobe wrote:

#2 is #2, whether it's Al or Cu -- it's the wire gauge and the gauge is independent of material. Only the conductivity of Cu is better than Al so can use smaller gauge wire compared to Cu for the same ampacity.
That said, #2 is roughly 0.25" diameter. See following link for table of AWG dimensions.
http://www.rbeelectronics.com/wtable.htm
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• posted on May 29, 2008, 6:31 pm

I'm not too familiar with fuse boxes, but in a typical breaker box, the main breaker is sized to match the size of the service. If my main breaker (the one at the top of the box that would kill the entire house if thrown) is labeled as 150A, then I have a 150A service.
I don't think you'd have a service wire size that was rated higher by any great extent than the main breaker (or fuse in your case) and you'd better not have a service wire size that was rated lower.
Do fuse boxes not have a "main fuse" for the entire system?

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• posted on May 29, 2008, 8:29 pm
wrote:

I'm not too familiar with fuse boxes, but in a typical breaker box, the main breaker is sized to match the size of the service. If my main breaker (the one at the top of the box that would kill the entire house if thrown) is labeled as 150A, then I have a 150A service.
I don't think you'd have a service wire size that was rated higher by any great extent than the main breaker (or fuse in your case) and you'd better not have a service wire size that was rated lower.
Do fuse boxes not have a "main fuse" for the entire system?
His particular fuse box has two main disconnects, and it was common for split buss breaker panels to have up to six main disconnects. The common misconception is that the total amperage of the main disconnects cannot exceed the rating of the service entrance cables. Theoretically you can have a 200 amp service with six 100 amp main disconnects.