Thread: SEC Amperage

Jerry, 200, 300 or 400 Amp? Those are 200 Amp breakers. Thanks.

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Originally Posted by Tom Rees

200, 300 or 400 Amp? Thanks.

Tom,

That would depend on two things not shown:
1) What size where those service entrance conductors? Copper, but what size/rating?
2) What was the rating of that equipment which was shown on its label?

The lesser of those two would be the rating.

Visually, the comparative size of the service entrance conductors are larger than the feeder conductors coming off the right 200 amp main, thus the service entrance conductor *might* be rated for 400 amps, but is the equipment rated for 400 amps (probably)? If so, then the service size would be 400 amps.

The left main feeds the panelboard below it and feeds through that panelboard to another panel someplace else.

The right main feeds another panel someplace else.

Thus you have 2 200 main disconnects (service disconnects) and 3 panels, 1 of which is 'part of' the service equipment.

The other panels would need to be rated for 200 amps minimum.

That top left SEC sure looks like aluminum inside the copper crimp lug and the right one copper.

Originally Posted by Bruce King

That top left SEC sure looks like aluminum inside the copper crimp lug and the right one copper.

Bruce,

Looked (looks) that way to me too, but I cannot imagine that any electrician could be THAT bad, so I wrote it off as the flash washing it out and that it was really copper.

Like comparing the right compression lug with the leg compression lug, the right one looks more copper and the left one looks whiter, less coppery in color.

Anyway, that was my thought process on it.

I agree, but it is factory wiring there not field installed.

Looks like a 320 amp maximum service panel. The copper SEC's are probably 250 amp but listed for 320 since they are contained in the assembly, short length and rated for a higher temperature.

I bet it has a 200 amp meter installed.

Or the panel could be a class 320 which is rated for 320 continuous and 400 max

I'd bet the left conductor at the top of the left breaker is tinned copper.

I'd also guess the meter combo is rated at 320 AMPs continuous, 400 AMP maximum rating. The size of the SECs has to either be rated for 400 AMPs or have load calculation support for smaller SECs. Though not universal, most AHJs won't allow smaller SECs on a residence. Homeowners just keep adding stuff. The heated towel racks and toilet seats, hot tubs, welders, etc. etc just blow away the load calcs that justify smaller SECs.

If additional panels have main breakers installed they don't need to be rated for 200 AMPs. If they are main lug only they do need to be rated for 200 AMPs