Subpanel In Metal Bldg

[JeffXD]

I have a 30 x 50 metal building with 200 amp service. Because of where the power came into the building my pain panel is 30 feet across the building from my main walk door. But.. I have a workbench, storage, etc just inside the walk door where I need power. Rather than run a light circuit all the way across, an outlet circuit all the way across, etc I was thinking running one circuit over for a subpanel to service that half of the building. I just don't want to be on the ladder running wire overhead any more than I have to... 1 is better than several.

So, my main panel is 200 amp. Run is 30 feet across + 6 feet up from the panel to the inside roof, and then 6 feet down on the other end. Guess that is 42 feet, so round up to 50 feet to be safe.

I am not running big tools on that side, just lights and a few 20 amp outlets for battery chargers, handheld tools, maybe the compressor, but no stationary saws.

It looks light most panels are 100 amp, I am not really seeing any 60 amp panels at HD or Lowes. With a 60 amp panel it was widely suggested to use 6-3 to get from there to there. I was looking at 6-3 UF since it looks like it doesn't need additional protection, even though most of this run will be 15 feet or so above the floor.

What do I need to make this happen?

 

[mm08822]

To cover the unknowns of the future, buy a 100 amp panel, no main required or with main - which ever you find cheaper, 24 space, need ground bar in sub. run 6-3 nmb, no uf required. put a 60 amp cb in main panel. larger cable/cb if needed, but doesn't sound like it.

 

[wyliesdiesels]

I agree with above.

UF-B doesnt have any more protection than NM-B. But its for underground use so u dont need it in the shop.

 

[matt_i]

If you run EMT then if you want more circuits (within reason up to conduit fill max) you pull out the fish tape and call over a buddy...no more ladder work needed.

A 100 amp panel is going to be $100 plus some #6-3 wire.

A 10 foot stick of 3/4" EMT is around $4. 50' is around $20 plus hangers, connectors, fittings, etc. Then you run #12 over there. For future proofing I'd put in a 12" x 12" x 6" NEMA-1 box (dustproof, with 4 screws to retain the cover). Punch the sidewall of that for future circuits as the need arises, use fish tape thru the trunk. Box is ~$35 at H.D.

It just doesn't seem right to me to put in a 100A subpanel 30 feet away from a 200A main panel to run some battery chargers and a power strip....

Adding: consulting conduit fill table for 3/4" EMT gives 16pc #12awg. Thats a lot of circuits...at least 5 x 20A circuits if you ran a homerun neutral and EGC for each one.

 

[sberry]

They make 8 space, same box as 6 just for this, about 30$.

 

[AntonLargiader]

It's just not that far across, and you'll still be running wire to things once you got there. If you want to future-proof that side of the building, OK, but for just a few lights and outlet circuits I'd simply run one or two 12-3 cables to the other side and have two or four 20A circuits that way (MWBC). Similar approach to Matt's suggestion.

I'm adding some circuits to my 30x60 shop, and for the most part that's how I'm doing the 20A stuff. The distances are just not that great.

 

[sberry]

I agree and 2 circuits is plenty, could be done with 1 cable or run and run another for the comp unless you are out of spaces. I use subs in my garage, 5 of them but its 80x80 with 20 ft ceilings. I got way more than I need but it was easy to do, got 10 circuits in a spot I use 4, 1 for lights and 2 for generals, 1 for a small water heater and the rest pretty much have 1 light bulb on occasionally.
A 6 space is about 20$ for the box, as I mention they make an 8 for this too and its not a terrible idea. It would double as a local disconnect for the comp. Its economical. It does make it easy if you get a problem child like a chop saw etc, simple to jump out of the panel for a tailored circuit/outlet etc. I got one, its the only one in the whole place.

 

[JeffXD]

Thank you!!

 

[JeffXD]

I have read over this a few times and one thing that pops out is I didn't think you could run nm-b through EMT and I didn't think I could just run it over without any protection. I don't really know how the who conduit thing works anyway. It kinda made my wife look at me funny, but I am thinking just to pull the meter and use a flashlight if I got out there at night.

Thanks again.

 

[matt_i]

I didn't specify above, but in my mind I was recommending pulling #12 awg stranded conductors, they will be individual spools of green, black, white (maybe red), also rated THHN/THWN as printed on the jacket. Available at any Low or Home D. Then you just need a steel fish-tape, carefully thread the fish tape thru the conduit, hook the wires and then pull thru the tube. Works very easily, although help is recommended to keep the wires going off the spools and into the tube from birdnesting.

You can put NM-B into conduit but that would not be my recommendation for the "up and over" EMT run I was visualizing. I don't think the first or especially the second would go in easy. The solid wires don't like traversing bends whereas the stranded conductors just flow around them, within reason.

The EMT is just a thinwall steel tube. Mount using 1-2 bolt hangers, connect with setscrew or compression connectors, bend where appropriate. Connect main panel to the NEMA-1 junction box via the EMT and now its basicallly a wire raceway, good for up to 16 conductors of #12awg size. There is a little more work setting up the EMT in the beginning, but once its in place, pulling the first wires or any additional wires is Cake.

Just be careful when using the fish tape around the open main panel due to the lugs and or bus bars which are possibly exposed, ideal is to de-energize the entire thing, or I duct tape up a cardboard protector as a temporary solution...