overcurrent size up or down

[kbrandt]

Can soneone tell me if I'am feeding a 100 amp panel for a mobile home from a pedestal can I use 1-3 SE cable (rated at 95 amps) or do I have to use 2-3 SE (rated at 130 amps).Looked for 3-3 SE can't find or they don't make it.I can't find in the code book if I can move up or down to next overcurrent device.If you could let me know what section or if I can use 1-3 SE.
Thanks for any help in advance.I believe it is 240.4 B

 

[charlie b]

240.4(B) does have something to say on this issue. But it is not where you start, and it will not answer your question.

Step 1: You begin by calculating the load.
Step 2: Then you pick a conductor that has adequate ampacity for that load.
Step 3: Finally, you pick an overcurrent device that will protect the conductor.

You have switched the order of Steps 2 and 3, and I do not know if you have performed Step 1.

What is the calculated load for the mobile home? If it is under 95 amps, then you can use a conductor rated at 95 amps, even if the panel is rated at 100 amps. If the calculated load is, let us say, 97 amps, then you cannot use a conductor rated at 95 amps. If you have not calculated the load, and if you have a 100 amp panel, then I would say you have to use a conductor rated at 100 amps or higher.

For the last step, if the calculated load is under 95 amps, and if you select a conductor rated at 95 amps, it would be acceptable to protect that conductor with an overcurrent device rated at 100 amps. That, and only that, is the role played by 240.4(B) in this situation.

 

[LarryFine]

Another thing, you got the wire sizes going in the wrong direction. Assuming you're talking about aluminum SE, the #2, rated at 90a (@75-C), may be used as a 100a feeder. #1, however, is larger than #2, not smaller, and has a higher ampacity.

 

[kbrandt]

I meant to say 4-3 copper at 95 amps,sometimes I think one thing and type another while thinking of what I need to do next.10 things at one time.Thanks for the help.

 

[ptonsparky]

We use Table 310.15(B)(6) for moblile home feeders. This is allowed in 215.2(A)(3). A #4 CU conductor would be allowed to feed the 100 Amp panel.

 

[benaround]

kbrandt,

How are you coming out of a pedistal with SE cable? Does the pedistal have

OCPD installed in it? If so, then you will need 4 conductors to the mobile

home.

 

[RUWired]

kbrandt,

How are you coming out of a pedistal with SE cable? Does the pedistal have

OCPD installed in it? If so, then you will need 4 conductors to the mobile

home.

Not to mention that the ground wire needs to be insulated as well.
Rick

 

[kbrandt]

Benaround and ruwired---coming out in pvc all the way to panel with 100amp ocpd at pedestal and all 4 wires are insulated.