Service wire size to breaker panel

[Scott Falvey]

1900's house with fairly recent breaker panel installation. The main breaker is 100 AMP, but the wire from the meter is the old cloth wrapped style and is about 1/2" in width. Does this seem like appropriate size for 100 amp panel?

Sorry, I don't have any "good" pictures.

Thanks all.

[Speedy Petey]

I would say it is "close". Was the 1/2" with or without insulation?

[Scott Falvey]

Hi Speedy,

That is including the cloth insulation.

[Jeffrey R. Pope]

If it's cloth wrapped, it's probably insulated with rubber. I would have no problem recommending replacement of rubber-insulated, tinned-copper if, in fact, that's what it is. Being a 1900 build, with that old wire, it's probably set up for 60 amps.

Of course, this is all speculation on my part

[Scott Falvey]

Hi jeff,

I think I tend to agree with you. My gut told me this looked undersized for the breaker panel, thus raising the question here.

I will look for further input here before I finish the report and send to the client in the morning.

[William E. Siegel]

I would have thought that they would also have upgraded the service to a minimum of 125 amps

[Scott Falvey]

Just reviewed my notes, wire is 5/8" across.

It amazing they don't upgrade higher especially when the service meters are all rated for 200 amp, including this one.

[Speedy Petey]

William, there is no such thing (for argument's sake) as a 125 amp service. Residential services run 100, 150, 200 & 400 (320) amps. Above that is rare.
There are 125 amp panels but this does not equate to service size.

Scott, the meter itself is actually irrelevant. It belongs to the POCO and most all plug in style are 200cl rated. They use the same meter from 100 to 320 amps.

[Greg Fretwell]

4ga SE might not be much bigger than that. The real answer is to measure the conductor itself. It is very possible that could be 6ga, left over from an old 60a service but you have to measure to know.

[jtedesco1]

Courtesy: www.nfpa.org

Has anyone used this table in their review of the sizes of services under specified conditions and permission to use smaller sizes of SEC's?

I was aware that Type SE cable is made with a grounded bare wire that is two sizes smaller than the hot legs, is that still true?

[Speedy Petey]

Originally Posted by jtedesco1

Courtesy: www.nfpa.org

Has anyone used this table in their review of the sizes of services under specified conditions and permission to use smaller sizes of SEC's?

I was aware that Type SE cable is made with a grounded bare wire that is two sizes smaller than the hot legs, is that still true?

It can also be had straight across, with not reduced neutral.
The reduced neutral is FAR more common though.

[Paul W. Abernathy]

Originally Posted by Speedy Petey

It can also be had straight across, with not reduced neutral.
The reduced neutral is FAR more common though.

Agreed....most of the services I do now are in PVC if possible and we use 2/0CU on all 3 lines ( 200A Service )......due to the increase of harmonics and so on and to be honest because we buy the 2/0 CU in long lengths.....but yes the SE usually has the smaller neutral......and Peter is correct they do have SE in equal sizes with all the same size conductors as well.

However I do see it MORE in SER than SE locally.....

[Greg Fretwell]

I looked in the Southwire catalog (the one I have handy) and it looks like all of their SE (3 wire) has a full size neutral. The SER (4 wire) has a downsized grounding conductor (per 250.122)