To subpanel or not to subpanel

[78SC4X4]

I'm probably overthinking this, but.........

I'm planning a 52x40 pole structure. Two 14' highbays on the left end and two 12' bays with loft on the right end. Due to the local power companies requirements and location of the transformer, the meter must be near the front left of the structure. I'm trying to include image, but not sure if I got it.

Unfortunately, most of my large electrical loads (welders, compressor, etc.) are on the other end of the building. Both bays will have typical light and receptacle circuits.

Would it make sense to run 4/0 to the other side and install a subpanel? I don't actually think it will save me any money when I'm all done, but It would be cleaner.

 

[sberry]

The easy way here is a 200A with feed thru lugs to another panel. I might downsize it to 2/0 and 2 inch pipe you can even put in the floor for this. Pipe under any door ways you want. Saves a lot of ladder time. I like another panel in a cas4e like this, saves so much branch circuit work and convenience. 60 ft of wire before a guy even starts a circuit.
Gives local disconnecting means.

 

[u2slow]

Pretty much what sberry said.

No harm in sub panels. Makes every branch circuit shorter. I'll probably have 3 panels in my 20x38' shop when I'm done.

 

[78SC4X4]

The easy way here is a 200A with feed thru lugs to another panel. I might downsize it to 2/0 and 2 inch pipe you can even put in the floor for this. Pipe under any door ways you want. Saves a lot of ladder time. I like another panel in a cas4e like this, saves so much branch circuit work and convenience. 60 ft of wire before a guy even starts a circuit.
Gives local disconnecting means.

Thanks. That is what I was thinking, but since I don't do this all the time, I wasn't sure. Under the floor is a really interesting idea. Also, are you suggesting cooper or just keeping the subpanel to 100amp?

 

[Innovate1]

I would say a sub panel or maybe even more than one would work well there. As others have said it makes the branch wiring shorter and easier. Sub panels don't cost that much. with a panel at each end you could split the branch circuits between them running them to the closest panel. In my house I put a sub panel in the attached garage and ran the nearby kitchen and house circuits to it as well as the garage. Kept the mass of cables going into the main panel more manageable.

 

[alfredeneuman]

The easy way here is a 200A with feed thru lugs to another panel. I might downsize it to 2/0 and 2 inch pipe you can even put in the floor for this.

2/0 copper is rated at 175A, not 200

 

[u2slow]

Also, are you suggesting cooper or just keeping the subpanel to 100amp?

Let the connected load at the far end decide.

Feed-thru lugs are intended to pass the full the supply current onward, without its own disconnect. A typical 200A residential panel can usually handle up to 125A on a breaker stab. You have to check the mfr's listings for exact specs and accessories available.

 

[78SC4X4]

Let the connected load at the far end decide.

Feed-thru lugs are intended to pass the full the supply current onward, without its own disconnect. A typical 200A residential panel can usually handle up to 125A on a breaker stab. You have to check the mfr's listings for exact specs and accessories available.

That's a fair comment. Square D does make a 200 amp Subfeed Plug in Lug Block for their homeline panels. But you are correct that I may not need that and could reduce cost with something lower.

 

[Terry D]

A sub panel would be the way to go, a lot easier running 1 larger cable verses multiple smaller ones.

 

[sberry]

2/0 copper is rated at 175A, not 200

Yes, I didn't finish and wasn't clear but meant 2/0 alum and a 150 panel, even 125, just downsize the wire a bit to make it more manageable.

 

[Kaizen]

Run aluminum to a sub panel and it will pay off in 6 months vs paying x amount every month just for the service
I ran 100 ft if 2/0 for like 150 bucks

Sent from my iPhone using The Garage Journal mobile app

 

[sberry]

You do not need to have 4/0 and feed 200 thru, you need a calculated load on the other end or a breaker appropriate for the wire. Its wired like a power strip in that case.

 

[alfredeneuman]

You do not need to have 4/0 and feed 200 thru, you need a calculated load on the other end or a breaker appropriate for the wire. Its wired like a power strip in that case.

That's called a feeder tap, and can't be over 25' of wire length long, unless outdoors or in a high bay manufacturing facility.
The sub's going to be at the other end of a 52' long building.
You cannot go the panel to sub without a breaker or fuses less than 25' away from the panel.
It's in Article 240.21(B)

 

[theoldwizard1]

Unfortunately, most of my large electrical loads (welders, compressor, etc.) are on the other end of the building. Both bays will have typical light and receptacle circuits.

Would it make sense to run 4/0 to the other side and install a subpanel? I don't actually think it will save me any money when I'm all done, but It would be cleaner.

I would say yes to the subpanel, but first I would take a good look at light switching and loads. As expensive as it might seem, you want you light switching as close to the main entrance as reasonable. Most commercial building just you the breakers as On/Off swithces.

Second, look hard at those "big" loads. How many will ever be used simultaneously ? In a wood shop, maybe a table saw and a dust collector. In a metal shop, maybe a plasma cutter and an air compressor. Do you ever plan on having a "welding party" and have buddies over with their welders to do simultaneous welding ? The point is 90A/100A to that subpanel is likely more than enough. You don't need 4/0 for that.

 

[Bert_]

That's called a feeder tap, and can't be over 25' of wire length long, unless outdoors or in a high bay manufacturing facility.
The sub's going to be at the other end of a 52' long building.
You cannot go the panel to sub without a breaker or fuses less than 25' away from the panel.
It's in Article 240.21(B)

Put conduit in the floor. That would be considered outside the building.

 

[sberry]

I forgot the 25 ft. Also didn't know if it was considered a true tap since there was ocpd between it and the meter base. I might crack the book since alfredeneuman quoted the section, it's in my office though.

 

[sberry]

A benifit of a feed thru is there are some breaker spaces vs a simple disconnect and they cost about the same. I was in one a while back was an upgrade poorly designed. Used a disc and would have saved a lot of work had it some spaces.

 

[alfredeneuman]

Put conduit in the floor. That would be considered outside the building.

It's got to start outside the building and terminate outside the building.
The only way to do that would be to put both panels outside

 

[78SC4X4]

I'm getting quite an education in this thread........

Can I put a 125 amp breaker in the first panel and then run underground direct burial distribution cable of the proper size in conduit under the concrete slab to the sub panel?

Looks like I need to be 18" deep below slab?

 

[u2slow]

I'm getting quite an education in this thread........

Can I put a 125 amp breaker in the first panel and then run underground direct burial distribution cable of the proper size in conduit under the concrete slab to the sub panel?

Looks like I need to be 18" deep below slab?

Check the sticker in the panel for the maximum size branch circuit allowed. And what wire size such a breaker will accept.

I don't know about how deep. I'm used to putting feeders and conduit *in* the slab, before the top layer of rebar.

 

[alfredeneuman]

Can I put a 125 amp breaker in the first panel and then run underground direct burial distribution cable of the proper size in conduit under the concrete slab to the sub panel?

Yes that would be the best way to do it
Instead of a cable individual wires would be easier to pull.

Looks like I need to be 18" deep below slab?

The burial depth for PVC under a building is 0 inches

 

[78SC4X4]

Yes that would be the best way to do it
Instead of a cable individual wires would be easier to pull.




The burial depth for PVC under a building is 0 inches

Got it. Thanks. I can dig 0 inch trenches all day long.

 

[TurnipTruck]

Got it. Thanks. I can dig 0 inch trenches all day long.

Don’t just lay the conduit on the ground and pour.
Make sure to bury the conduit under the foam/mesh/tubes/whatever is in the slab. In other words, don’t make an abrupt concrete thickness change or the slab WILL CRACK ALONG THE CONDUIT. Ask me how I know.

 

[78SC4X4]

Yes. I'll set it just below the surface. So, I guess I'm really digging 2-3 inches

The insulation board and radiant heat/rebar will sit on top of it.

 

[Ron_J]

I've been considering a subpannel in my 30x50, but wasn't sure if it would be beneficial.

 

[alfredeneuman]

I've been considering a subpannel in my 30x50, but wasn't sure if it would be beneficial.

Then make you own thread and ask?

 

[Ron_J]

Then make you own thread and ask?

If I come up with a specific question, I will probably do that.

I just meant that this thread had some good info in it that helped.

 

[alfredeneuman]

If I come up with a specific question, I will probably do that.
I just meant that this thread had some good info in it that helped.