Can I run a load "backwards" through the feed from main panel

[Ironcrow]

I have a 400A main panel on a pedestal feeding two 200A subpanels, one on the shop and one on the house. Due to a perfect storm of weird coincidences I would like to do something odd. I can't find the right google terms to find an answer. The house panel is pretty full with water heaters, two ACs, hot tub - living the American dream. Wife wants to add huge pottery kiln on the house side.

Over in the shop I have the typical big loads that never run all at once; lift, compressor, welder, plasma, mill, lathe. Also, as a result of another screw-up, the feed from the 400A panel to the shop is a 20 foot run of - no lie - 3 inch EMT (don't ask).

So, I'd like to add a 60A breaker to the shop subpanel to feed a new kiln in the house. It would really simplify my work if a could shove the wire from that breaker back through the feed from the 400A (plenty room in 3 inch EMT) and loop it through the main panel and run it out to kiln. In my mind of course it will work, but is there something not code kosher about running a load back through the shop subpanel feed?

 

[patrickoneal]

I have a 400A main panel on a pedestal feeding two 200A subpanels, one on the shop and one on the house. Due to a perfect storm of weird coincidences I would like to do something odd. I can't find the right google terms to find an answer. The house panel is pretty full with water heaters, two ACs, hot tub - living the American dream. Wife wants to add huge pottery kiln on the house side.

Over in the shop I have the typical big loads that never run all at once; lift, compressor, welder, plasma, mill, lathe. Also, as a result of another screw-up, the feed from the 400A panel to the shop is a 20 foot run of - no lie - 3 inch EMT (don't ask).

So, I'd like to add a 60A breaker to the shop subpanel to feed a new kiln in the house. It would really simplify my work if a could shove the wire from that breaker back through the feed from the 400A (plenty room in 3 inch EMT) and loop it through the main panel and run it out to kiln. In my mind of course it will work, but is there something not code kosher about running a load back through the shop subpanel feed?

Why not just feed another subpanel or disconnect off the 400A main panel for the kiln? That seems like the simplest thing to do, but I haven't seen what you've got.

 

[Norcal]

No, only one feed to a structure allowed.

 

[buddyboy]

I'm not an electrician.

Can he change the service to the house to a 400 amp service, then from that 100 amp subpanel out to the shop. this way he will have more than enough at the house to run whatever?

 

[wyliesdiesels]

I have a 400A main panel on a pedestal feeding two 200A subpanels, one on the shop and one on the house. Due to a perfect storm of weird coincidences I would like to do something odd. I can't find the right google terms to find an answer. The house panel is pretty full with water heaters, two ACs, hot tub - living the American dream. Wife wants to add huge pottery kiln on the house side.

Over in the shop I have the typical big loads that never run all at once; lift, compressor, welder, plasma, mill, lathe. Also, as a result of another screw-up, the feed from the 400A panel to the shop is a 20 foot run of - no lie - 3 inch EMT (don't ask).

So, I'd like to add a 60A breaker to the shop subpanel to feed a new kiln in the house. It would really simplify my work if a could shove the wire from that breaker back through the feed from the 400A (plenty room in 3 inch EMT) and loop it through the main panel and run it out to kiln. In my mind of course it will work, but is there something not code kosher about running a load back through the shop subpanel feed?

No u cant do that. As has already been said, u cant have 2 feeds to a structure. BTW does this EMT run underground?

Why not do a subpanel off the panel in the house? Move one circuit(240v) from the house panel to the subpanel to free up a breaker space...

I'm not an electrician.

Can he change the service to the house to a 400 amp service, then from that 100 amp subpanel out to the shop. this way he will have more than enough at the house to run whatever?

U mustve not read the OP. He said he HAS 400a service. Moving that to the house from the pedestal would be cost probibitive. he already has 200a in the shop so why would he change that to 100a?

The real issue is space in the house panel....so do a subpanel off the house subpanel.

 

[Zeke]

No u cant do that. BTW does this EMT run underground?

Why not do a subpanel off the panel in the house? Move one circuit(240v) from the house panel to the subpanel to free up a breaker space...



U mustve not read the OP. He said he HAS 400a service.

U mustve not read the OP. He said he HAS 400a on a pedestal.

 

[Ironcrow]

Actually it 3 inch EMT up the wall, then turns into 3 inch schedule 80 CPVC to complete the run underground.

The other thing that sticks in my mind is the 10kW solar system is on the shop backfeeding that subpanel so I favor using that subpanel for additional loads. But after thinking about this post I'm starting to feel stupid. The solar system doesn't care whether its hooked to the shop subpanel or the 400A panel.

I think I can terminal block into the 400A panel for the kiln, that solves my problem (still no additional conduit needed). Or subpanel the house subpoena. That's a good idea too.

 

[theoldwizard1]

So, I'd like to add a 60A breaker to the shop subpanel to feed a new kiln in the house.

IANAE (I am not an electrician), nor a "code lawyer", but somewhere I recall that a building can only have "one feed", so the answer is no.

Now, if the kiln was outside in a shed, the answer would be yes !

 

[theoldwizard1]

Why not do a subpanel off the panel in the house? Move one circuit(240v) from the house panel to the subpanel to free up a breaker space...

Replace a couple of single breakers with tandems. Instant 2 slots.

Unless you have some massive AC units (note plural) I can not imagine that a 200A panel would not have enough capacity.

Tell her to not run the electric dryer for the couple of days the kiln is fired. (Arizona ... who needs a clothes dryer !)

 

[pattenp]

No, only one feed to a structure allowed.

In this case I think it would be allowed. The feeder back is not a service and under 2011 NEC 225.30 where a feeder originates in an additional building, one feeder is allowed to provide power back to the original structure.

Edit: Ooops... I'm wrong. I wasn't thinking about the service is at a pedestal feeding two separate 200A panels at separate buildings. I was thinking of the main 400A service being at the house and the shop being fed from the house. I should know better than to question an answer from Norcal.

 

[buddyboy]

yep I got confused, I thought he had 400 amp service at the pedestal with a 200 amp subpanel at the house and a 200 amp subpanel in the shop. with the house actually drawing at almost capacity and the barn not even close to drawing at capacity. I thought the OP was looking to use some of the unused capacity at the shop to power his wifes kiln at the house by running a circuit from the shop to the kiln.

sorry this is why I am not an electrician. My kindergarten teacher was wrong about no stupid questions.

lol

 

[Ironcrow]

yep I got confused, I thought he had 400 amp service at the pedestal with a 200 amp subpanel at the house and a 200 amp subpanel in the shop. with the house actually drawing at almost capacity and the barn not even close to drawing at capacity. I thought the OP was looking to use some of the unused capacity at the shop to power his wifes kiln at the house by running a circuit from the shop to the kiln.

sorry this is why I am not an electrician. My kindergarten teacher was wrong about no stupid questions.

lol

That is correct.

Actually the kiln IS in a "studio" (shed) next to the house....

The 200A at the house is probably not at "capacity" for current, but all the slots are full with important stuff.

 

[buddyboy]

then can't you just put a sub-panel next to your house panel to give you more slots?

 

[wyliesdiesels]

U mustve not read the OP. He said he HAS 400a on a pedestal.

I did read that. I was in a hurry on my way to work and didnt finish my comment.

 

[Ironcrow]

then can't you just put a sub-panel next to your house panel to give you more slots?

Yes, I was erroneously stuck on the idea that to take advantage of my solar I had to breaker into the shop panel, but after actually thinking about it, both subpanels are paralleled to the pedestal, so it makes no difference.

 

[wyliesdiesels]

U have one meter so thats correct it doesnt matter.

I assume u will have lighting in the shed. I would put a subpanel in the shed. U will need a 4-wire feeder and 2 ground rods. Also, the neutral bus needs to be isolated from the ground bus bar and enclosure...

 

[Ironcrow]

I have two meters, one is for just the solar panels. But, yes, one revenue meter for the main feed from the power company. It runs backwards on a sunny day. I think it is a good idea to just add a subpoena in the shed, I'm going that way.

 

[NUTTSGT]

I have two meters, one is for just the solar panels. But, yes, one revenue meter for the main feed from the power company. It runs backwards on a sunny day. I think it is a good idea to just add a subpoena in the shed, I'm going that way.

IANAE, but I'm guessing autocorrect ?

 

[Ironcrow]

Dam auto erect!