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wire size and amp rating

I have an underground wire that I think is called #8-3 but I can't find any numbers on it. The OD of the insulation is 0.238" on each of the three wires. That in turn is in another insulated jacket for underground. Each wire is a seven stranded unit, the O.D. of this is 0.145" and each wire measures 0.048". What's the wire size here?

More importantly, I need to know amp capacity. There's four of these #8?-3 wires in a conduit for four feet going from the main to underground. (Multiconductor may reduce amp rating?)

I want to go 40 amp circuit breaker. Am I OK

Karl

Reply to
Karl Townsend
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Keep looking. It's there -- you just haven't found it yet.

Not relevant.

Dunno. The standard for AWG8 is 0.128", AWG7 is 0.144" -- and AWG7 would be unusual, to say the least, for electrical wire.

Not possible to answer, without knowing exactly what kind of cable you have. It's marked somewhere on the cable sheath. Keep looking.

Reply to
Doug Miller

#8 sounds right.

Unless the insulation is something very unusual (rated less than 60 degrees C) it should be fine.

Reply to
Ned Simmons

8's not that big -- unless he's measuring the insulation, not the wire, in which case he has a meaningless measurement.

And that's why I told him he needs to find the markings on the cable.

Reply to
Doug Miller

Seven strands of .048 diameter wire totals 16,128 circular mils cross section. AWG #8 has an area of 16,512 circular mils - close enough to chalk up the difference to measurement error.

Best to identify the wire and be sure, but, as far as I know, there are no NEC listed wires with an insulation rated below 60C.

Reply to
Ned Simmons

Seems to me there should be some pi there, and r ^2 instead of d ^2, giving 12,667. or am I talking trough my left ear? Gerry :-)} London, Canada

Reply to
Gerald Miller

Prooved myself wrong again - il-logical system! Gerry :-)} London, Canada

Reply to
Gerald Miller

My concern is that, unless the OP finds the markings on the cable, there is no assurance that this *is* an NEC-approved cable.

Reply to
Doug Miller

Is the 0.128" Diameter for AWG 8 for solid or stranded wire? I calculated the area of a .128" Dia. circle, I then calculated the diameter of wire for

1/7th that area and came up with 7 strands of 0.04838" dia. wire has the same area as a solid 0.128" wire.

In McMaster Carr, their AWG 8, 4 conductor copper stranded wire Amp rating ranges from 35Amps to 63Amps. This was for service cord, not really what the OP is likely to have burried underground.

On the website linked below, the 3rd table down lists size and Amp ratings.

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RogerN

Reply to
Roger_N

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