Wire Type Q - Main disconnect to panel

[sands35]

Particulars:

A ~50 year old house with what amounts to industrial electrical equipment.

I have a Square D fused 200 amp main disconnect feeding a main panel on an opposite basement wall. ~20 foot run. (panel is not in service currently, I want to use it to feed a sub-panel that will be on the 2nd floor. I am going to replace non-grounded tar paper wire with NM.)

Panel in question is the middle one.

Run is 100% in the basement.

Question:
What are my options for type of cables to support 200 amp service? Run is about 20 feet. 4/0 THHN is stupid expensive - so looking for alternatives. I can put up conduit of any size - basement is unfinished.

Can I use SEU, SER, URD or MHF if I put it into conduit?

Since the panel is going to only have a 60 amp sub and a few misc 20 amp outlet circuits on it, I could just use a 100 or 125 amp panel with a disconnect on it. I haven't looked to see if there are ~100/125 amp fuses that will fit into the disconnect either. That might work as well to control wire costs.

(long story short - the house was built by a former CEO of a company. He has some $$$ to burn and overdid the electrical just a little bit. Stuff on the right is equipment for electric driveway heaters. I've been too scared to turn them on.)

 

[alfredeneuman]

Are you going to leave the panel in the basement out service permanently?
If you are then this:

125 amp fuses will fit right into a 200 amp disconnect. 100s will not.

1/0 aluminum wire is the size to use for a 125 amp wire, with a #4 aluminum ground wire.
Because of the need to increase the conduit size with cable, you'd probably be better off pulling the individual conductors.

If you aren't then none of this applies

 

[sands35]

I was going to leave those Square D disconnects there. I'd like to leave the existing panels there as well, but replace the wires to so they are properly sized. House has had ~6-7 owners in the last 50 years - no telling who did what, but what is in there isn't the right size currently. (you can just see the "main" panel to the left of the left hand disconnect.)

As long as I put it into conduit, what type of wire can I use inside a house? (SEU, SER, URD or MHF).

Can I put USE in a conduit and use it inside the house?

Good to know about the 125 fuse. I might pick one up on the way home and see if it will work.

 

[MTW]

The 200A disconnects could be fused down to whatever size is needed with the proper fuse reducers 200 to 100, 200 to 60, 200 to 30, and the appropriate fuses.
http://www.cooperindustries.com/content/public/en/bussmann/electrical/products/accessories/class_h_j_k_r.html

Looks like those small subpanels to the right might be connected to the service entrance conductors in the trough below the switches. If so that may be an issue, they should have a main breaker in each. Doesn't look they do.

The code limits you to 6 disconnect/breakers to kill all power to the building/property.

Suggestion- replace the 2 small subpanels to the right with a 200A 42CKT loadcenter with a Main. Reconnect the existing circuits, and add a new feeder for the upstairs of whatever size you like. Then you could use the remaining capacity for any basement circuits that you may need in the future.

If you can install conduit to the 2nd floor, XHHW aluminum conductors would be my choice. Here's some #2 Alu rated at 75A, 60Deg C
http://www.homedepot.com/p/Southwire-500-ft-2-Gauge-Stranded-XHHW-Wire-Black-11272207/204786553

MTW Ω

 

[sands35]

Good to know on the fuse reducers. I figured something like that was made, but couldn't find them.

That stuff on the right is for the driveway snow-melters. I'll probably simply take them out of service and nut off the wires feeding them. Driveway is old and cracked and they are probably NFG anyway. Even if they worked, they would be stupid expensive to run. The 1st box to the right off the square raceway is the disconnect for the snow-melters. I do not remember the amp rating on that. If I ever sold the house, I would need to have them serviced. Servicing them would probably cost more than a few years of payments for a snow plow service. Just not worth it to fix them if they needed to be fixed.

The panel wired into the middle square D isn't in the photo (the one I want to bring back into service.)

What types of wire can I run inside conduit in a house (SEU, SER, URD or MHF)?

 

[pattenp]

Not URD.

 

[wyliesdiesels]

Since its coming off a disconnect, u need 4-wire.

Do u really need 200a? Whatever wire u use will be expensive.

If u step it down to 100a, I would go with SER as u dont need conduit as long as its not subject to damage.

For SER @ 100a, u could go with 3-3-3-5 CU SER or 1-1-1-3 AL SER.

MHF requires conduit inside so thats more work than the SER.

URD cant go inside, and SEU has a concentric neutral and no ground and is for 3-wire service entrance use

 

[sands35]

Great, just what I needed to know.

It will be stapled to the bottom of the ceiling rafters of the basement. Avoiding conduit would be a plus.

No, I don't need 200 amps. There are 3 panels in the house! I think I can distributed loads well enough to avoid issues.

The house was built in 1962, so that is probably something relevant.

Currently, there are three wires to the breaker panels from the Square D disconnects. L1, L2 and Ground. The Ground and Neutrals are bonded in the breaker panel.

If current code is to have them only bonded in the disconnect, then I can do that.

 

[wyliesdiesels]

Yes, u need to run 4-wire to any new panels from the disconnects. Neutral needs to be isolated from the panel and ground bar.