Thread: What size are these service wires?

Condo today had a 400 amp disconnect at the exterior closet. Huge copper service wire in Challenger distribution panel in utility room (diameter of wire seemed to be as large as a nickel). Any idea what size copper wires these are.

Any thoughts why a condo complex of 4 units has this much amperage to each unit.

Also the door seemed to weigh 10 pounds and had to be removed to access the recessed dead front cover.

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Originally Posted by sidney alstad

Condo today had a 400 amp disconnect at the exterior closet. Huge copper service wire in Challenger distribution panel in utility room (diameter of wire seemed to be as large as a nickel). Any idea what size copper wires these are.

Any thoughts why a condo complex of 4 units has this much amperage to each unit.

That is quite new wire. The size is written right on it. I can see it but cannot make it out in the pic.
Did you not look at the wire for the size?

Are you saying EACH unit had 400A, or 400A split between four units?

There were 4 400 amp disconnects. I do not think the wire was new, was much larger than 4/0 and markings were not legible to me.

If it is a 400 amp breaker the copper wire should be 400 AWG....

Originally Posted by James Duffin

If it is a 400 amp breaker the copper wire should be 400 AWG....

Huh?

If the main disconnect size is indeed 400 amps, then the copper conductors would need to be:
- older equipment with 60 degree C rated terminals: 750 kcmil
- newer equipment with 75 degree C rated terminals: 600 kcmil

400 kcmil (which I think you might have been referring to) is only rated for: (respectively based on above equipment)
- 280 amps
- 335 amps

Sidney,

The best way to tell the size is to read the printing on the side of the conductors, shown in white in your photo.

Jerrry, Table 310.15(B)(6) would apply here since these are individual dwelling units of a multi-family building, so 400mcm CU is correct.

No way I'd say it actually was 400 unless I saw it on there.

Originally Posted by sidney alstad

There were 4 400 amp disconnects. I do not think the wire was new, was much larger than 4/0 and markings were not legible to me.

Heck, I can almost make it out in the pic.
Were they not physically legible, or did you not know what it meant? I would hope not the latter.

Originally Posted by Speedy Petey

Jerry, Table 310.15(B)(6) would apply here since these are individual dwelling units of a multi-family building, so 400mcm CU is correct.

No way I'd say it actually was 400 unless I saw it on there.

You are correct, I didn't read far enough when I went back and reviewed:
"(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders. For individual dwelling units of one-family, two-family, and multifamily dwellings,"

... skipping the: "and multi-family dwellings" part.

Unsure if there was a breaker. Only saw the disconnect from the first picture, there were 4 of these and they were not labeled per unit, could not be opened without turning off all power, thus were not opened nor inspected and will write up report that way. I was thinking that these may be inappropriate cable for service wire.

Originally Posted by Speedy Petey

Jerry, Table 310.15(B)(6) would apply here since these are individual dwelling units of a multi-family building, so 400mcm CU is correct.

Originally Posted by Jerry Peck

You are correct,...

As long as that is not a 3-phase system that is part of. And many condos do have 3-phase systems.

after magnification, what I can make out on the wiring may be AMD OIL RESISTANT followed by what looks like II, then OB AWM (UL) 600V

Condo constructed in '86

In most panels with door handle disconnects ....there is a way to defeat the interloc....so that you can open the door (without turning off power) for inspection, trouble shooting, etc.