2 questions: grounding and feeders

[TOOL_5150]

1: Is 250.122 the table I use to size an EGC for a subpanel [feeder]

2: Where is it permitted or not permitted to feed [2] 200A sub panels off of [1] 200A main breaker. Going to run a 4/0 SER from 200A metermain to a j-box, then down to two 200A MCB panels side by side.

~Matt

 

[benaround]

1: Is 250.122 the table I use to size an EGC for a subpanel [feeder]

2: Where is it permitted or not permitted to feed [2] 200A sub panels off of [1] 200A main breaker. Going to run a 4/0 SER from 200A metermain to a j-box, then down to two 200A MCB panels side by side.

~Matt

#1. Yes

#2. As long as all the equipment and conductors are rated not less than the OCPD.

side note: the 2 panels inside could be MLO if you wanted.

 

[DARUSA]

1: Is 250.122 the table I use to size an EGC for a subpanel [feeder]

2: Where is it permitted or not permitted to feed [2] 200A sub panels off of [1] 200A main breaker. Going to run a 4/0 SER from 200A metermain to a j-box, then down to two 200A MCB panels side by side.

~Matt

1- yes 250.122 is ok
2 As long your total load calculation is less than 200 amps you will be ok ( use the correct size of wire for the tap)

 

[TOOL_5150]

#1. Yes

#2. As long as all the equipment and conductors are rated not less than the OCPD.

side note: the 2 panels inside could be MLO if you wanted.

Thank you - You know when you think about something so much, you start to question yourself.. thats what happened to me, LOL.

Yeah, MLO makes sence, but I can get some MCB's for a real good price.

~Matt

 

[Volta]

Thank you - You know when you think about something so much, you start to question yourself.. thats what happened to me, LOL.

Yeah, MLO makes sence, but I can get some MCB's for a real good price.

~Matt

Just remember to order the grounding bars . . .

 

[infinity]

Does anyone see a problem with the #4/0 SER protected at 200 amps?

 

[Volta]

And SER 4/0 aluminum as an interior feeder only has an ampacity of 150. I'd say it needs to be protected that way.

If in raceway or other approved means, then a tap rule might help, and you wouldn't need the help for xhhw anyway. :roll:

 

[augie47]

In some of the jurisdictions here the 4/0 SER would be limited to the 60? rating of 150 amps.

 

[infinity]

And SER 4/0 aluminum as an interior feeder only has an ampacity of 150. I'd say it needs to be protected that way.

If in raceway or other approved means, then a tap rule might help, and you wouldn't need the help for xhhw anyway. :roll:

In some of the jurisdictions here the 4/0 SER would be limited to the 60? rating of 150 amps.

1: Is 250.122 the table I use to size an EGC for a subpanel [feeder]

2: Where is it permitted or not permitted to feed [2] 200A sub panels off of [1] 200A main breaker. Going to run a 4/0 SER from 200A metermain to a j-box, then down to two 200A MCB panels side by side.

~Matt

So in answering the original two questions:
1-Yes
2-Not permitted to use #4/0 SER protected at 200 amps.

 

[jwjrw]

So in answering the original two questions:
1-Yes
2-Not permitted to use #4/0 SER protected at 200 amps.

Unless the panels and wiring are all outside the building correct? If outside 4/0 would be ok correct?

 

[Volta]

Unless the panels and wiring are all outside the building correct? If outside 4/0 would be ok correct?

Yes, but only as 180 amp max each.

 

[Dennis Alwon]

If this is a meter main than I see no problem with the 4/0 aluminum as long as it feeds the total load of the dwelling. We are assuming dwelling here.

I would run the 4/0 to one panel then jump to the other panel with a 100 or 125 amp feed.

 

[infinity]

I'm wondering why you need 80 circuits in the first place with only a 200 amp service?

 

[LarryFine]

Does anyone see a problem with the #4/0 SER protected at 200 amps?

Doesn't 215.2(A)(3) permit this?

 

[Volta]

Doesn't 215.2(A)(3) permit this?

But the OP stated that this 4/0 from the main would be spliced a an exterio j-box to two sets of conductors.

[215(A)(you meant 2, right?)] requires "the total load" to be carried for that section.

 

[Dennis Alwon]

But the OP stated that this 4/0 from the main would be spliced a an exterio j-box to two sets of conductors.

[215(A)(you meant 2, right?)] requires "the total load" to be carried for that section.

The 4/0, even though it goes to 2 panels, does carry the entire load of the dwelling.

 

[augie47]

The relationship between the requirements of 338.10(B)(4), 215.2, and 310.16(B)(6) has been much discussed in previous threads and enforcement definitely varies between AHJ's.
Although you may not find anything "concrete", a search thru previous threads using "338.10" will provide you with many minutes of interesting reading.

 

[Volta]

The 4/0, even though it goes to 2 panels, does carry the entire load of the dwelling.

Yes, the first one does, agreed. It is the second sets of conductors (that I assume are SER), that will be interior feeders that I claim need to used at 60 degrees C, or 150 amp max (assuming aluminum).

 

[Dennis Alwon]

Yes, the first one does, agreed. It is the second sets of conductors (that I assume are SER), that will be interior feeders that I claim need to used at 60 degrees C, or 150 amp max (assuming aluminum).

My understanding is that there is an external meter main then 4/0 ser that goes to a JB then taps to both panels. There are not two sets of conductors.IMO.

 

[Volta]

My understanding is that there is an external meter main then 4/0 ser that goes to a JB then taps to both panels. There are not two sets of conductors.IMO.

1: Is 250.122 the table I use to size an EGC for a subpanel [feeder]

2: Where is it permitted or not permitted to feed [2] 200A sub panels off of [1] 200A main breaker. Going to run a 4/0 SER from 200A metermain to a j-box, then down to two 200A MCB panels side by side.

~Matt

If they are taps they are not properly protected. If they are simple splices, they may or may not be properly protected, depending on interpretation.