Wire from main to sub panel

[rwilly]

Hello all, I’m looking at my options to get power to my new shop.
The pic is of the main panel at the house.

To connect my sub panel, I, or the certified electrician, would get a breaker similar to the Main Principal and mount it at bottom of the bus bars, to connect the feeder cable?

I’d like to mount the conduit at the bottom of the main, run it out through the wall, down into trench, back up garage wall and into the sub panel.

As far as grounding goes, there is 2 pieces of rebar stubbed out through the sill plate. The rebar runs throughout the footers.
That is for grounding my sub panel to?



Thanks!

 

[theoldwizard1]

You just need a standard 2 pole breaker, of the size appropriate to protect the size of the wire.

As for cable, you need 4 conductors, 2 hots, neutral and ground. All should be connected inside the main panel. MHF cable is a good choice, but it must be run inside conduit above the ground. Many suggest using conduit, end to end.

 

[acer66]

The two stubbed out rebars are most likely ufer grounds but they need to follow certain specifications.

Was an ufer ground in the plans when you build your new garage and just to make sure your garage is detached right?

 

[wyliesdiesels]

Hello all, I’m looking at my options to get power to my new shop.
The pic is of the main panel at the house.

To connect my sub panel, I, or the certified electrician, would get a breaker similar to the Main Principal and mount it at bottom of the bus bars, to connect the feeder cable?

no you dont need the same breaker as the main. you just need a sq d 2 pole breaker of appropriate size for the feeder.

I’d like to mount the conduit at the bottom of the main, run it out through the wall, down into trench, back up garage wall and into the sub panel.

As far as grounding goes, there is 2 pieces of rebar stubbed out through the sill plate. The rebar runs throughout the footers.
That is for grounding my sub panel to?

Thanks!

no that would be the electrode ground (if done properly in the footing) but you still need an EGC ground going back to the main panel.

check the electrical FAQs sticky for diagram of how to wire it properly.

 

[rwilly]

Looking over the plans, I don’t see anything about UFER grounds.
I don’t see any other reason to stub out 2 pieces of rebar.
I’m sure the contractor didn’t do me any favors, unless this is how he does every garage. That is more likely the case.

This pic is what I could use for the cable.

Edit: it’s a detached garage, about 200’ from house.

 

[Zeke]

You can check the rebar for resistance. But it's easy to drive ground rods if the soil isn't frozen. Rent a demo hammer, the rods fit the chuck. Takes about a minute per.

 

[acer66]

Looking over the plans, I don’t see anything about UFER grounds.
I don’t see any other reason to stub out 2 pieces of rebar.
I’m sure the contractor didn’t do me any favors, unless this is how he does every garage. That is more likely the case.

This pic is what I could use for the cable.

If you can not verify that those are ufer grounds I would just do the usual two ground rods if your garage is indeed detached.

 

[acer66]

Rent a demo hammer, the rods fit the chuck.

I wish I had known that before getting a bit for that.

 

[wyliesdiesels]

Looking over the plans, I don’t see anything about UFER grounds.
I don’t see any other reason to stub out 2 pieces of rebar.
I’m sure the contractor didn’t do me any favors, unless this is how he does every garage. That is more likely the case.

This pic is what I could use for the cable.

Edit: it’s a detached garage, about 200’ from house.

thats the wrong breaker. thats a bolt on breaker.

 

[pattenp]

You need a standard 2 pole breaker that's like the other 2 pole breakers in your panel, but of the correct amperage. A 100A breaker will require at least #1 Al or #3 Cu feeder. At 200ft you will need to estimate your load to adjust the wire size for voltage drop.

 

[Zeke]

I wish I had known that before getting a bit for that.

Yeah, I bought the HF one on the cheap before tariffs and all that. I keep stupid things because they work until they don't and then the go in the bin. The cord is so stiff I could use it as a coat hanger, but it will drive a 8 or 10' rod easy as it gets. You just got to hoist the MF'r up to over 8' to get started. That's the hardest part.

 

[acer66]

Yeah, I bought the HF one on the cheap before tariffs and all that. I keep stupid things because they work until they don't and then the go in the bin. The cord is so stiff I could use it as a coat hanger, but it will drive a 8 or 10' rod easy as it gets. You just got to hoist the MF'r up to over 8' to get started. That's the hardest part.

Yup, use it mainly to set rods for electric gate openers so the ground is often not level/flat so hoisting a proper jack hammer up there is defiantly the most fun part.

 

[sparky 1971]

The breaker will look like this. 60 amps is probably plenty and #2 MHF would be perfect.

Homeline 60 Amp 2-Pole Circuit Breaker(HOM260CP)

 

[rwilly]

The breaker will look like this. 60 amps is probably plenty and #2 MHF would be perfect.

Homeline 60 Amp 2-Pole Circuit Breaker(HOM260CP)

That would enough to run 200’ going to a 100amp sub panel?
I plan on about 24-30 outlets, LED lighting, enough power for drill press, compressor, things like that.
I will eventually be putting in plugs for a welder and possibly a car charger.

 

[sparky 1971]

That would enough to run 200’ going to a 100amp sub panel?
I plan on about 24-30 outlets, LED lighting, enough power for drill press, compressor, things like that.
I will eventually be putting in plugs for a welder and possibly a car charger.

It won't be enough for a 100 amp circuit, but plenty for a 60 amp sub.. At 200' you'll probably have to run 1/0 aluminum or #2 copper at the minimum.

 

[rwilly]

Thanks for all your replies.

I went to HD looking for a panel, but they didn’t have what I was looking for.

The panel in the garage will probably be overkill, just like the one on my house, I think the main is 20, or 24 spaces and I only use half of them.

Eventually, the house will be torn down and the garage will remain. I want to build a house someday because the existing house, while it’s fine for me, isn’t a place to raise a family.
The women folk wouldn’t live in my house.

 

[wyliesdiesels]

That would enough to run 200’ going to a 100amp sub panel?
I plan on about 24-30 outlets, LED lighting, enough power for drill press, compressor, things like that.
I will eventually be putting in plugs for a welder and possibly a car charger.

if this is a one man shop, 100a is way overkill.... 60a would be plenty.... most of those loads are low amperage except for the car charger... if you have to have the car charger will running the other loads then youll need more than 60a...

 

[rwilly]

Overkill….other than being a waste of money buying the bigger panel and accessories, would there be any other negatives?
Any dangers?



Last thing I want to do is burn the place down!

 

[acer66]

Besides spending more of your money there is really no downside besides maybe its bit harder pulling the bigger wire etc..

Doing a proper load calculation and future proofing which is a bit more tricky since a lot of those things might never happen is the key.

I personally would plan for an EV charging station if financial feasible since that might also a selling point even if you do not use it.

The danger comes from not doing it right not from oversizing things.

 

[rwilly]

Started the trench.

 

[rwilly]

I got power!

The lights are running on extension cords until I get wiring done. There is a GFI needed for ceiling receptacles, my lights will plug into them, does the GFI need to be placed before, or after the switch? I was going to put it inline before the switch.

I’ll have to fine tune everything and get it signed off. I’ll get the inspector out and have him do his thing, then I can finish up, it will take awhile to finish up, but at least I’ll be doing it under the lights.

I’ve got a roll of Ethernet cable coming so I can have music and internet.

I was quoted between $6-$8K from local contractor to do this.
I did it myself for about $2K.

 

[acer66]

I got power!


I’ll have to fine tune everything and get it signed off. I’ll get the inspector out and have him do his thing, then I can finish up, it will take awhile to finish up, but at least I’ll be doing it under the lights.

I was quoted between $6-$8K from local contractor to do this.
I did it myself for about $2K.

Congratulations and besides saving a lot of money I am sure that it feels also great having done it yourself.

 

[dave*99]

I got power!

The lights are running on extension cords until I get wiring done. There is a GFI needed for ceiling receptacles, my lights will plug into them, does the GFI need to be placed before, or after the switch? I was going to put it inline before the switch.

You can do that. Use a GFCI breaker in the panel or use a GFCI receptacle it in an accessible spot (no ladder needed) Or use a dead front GFCI in a junction box also in an accessible spot..

 

[rwilly]

I’ve got 6 outlets, and my lights wired up.
Using two 15A breakers for the lights, and two 20A breakers for the outlets.
Now I have to call the inspector and get it all signed off.

 

[beemerphile]

Well, I"d say you certainly grounded the **** out of it. Are each of those stranded ground wires going to a grounding electrode? I'd have tied the rebar into the ground system whether it is a proper ufer or not just because it is there.

 

[rwilly]

The two ground wires are running to a rebar.
I did not use grounding rods.
I thought it was either/or.

 

[wyliesdiesels]

The two ground wires are running to a rebar.
I did not use grounding rods.
I thought it was either/or.

if you have a UFER, you dont need rods...

 

[beemerphile]

if you have a UFER, you dont need rods...

True, but he does not know if he has a proper ufer.

 

[rwilly]

I’m willing to take the chance that I do have UFER. If I don’t, the inspector will let me know, and I’ll remedy the situation.

I was googling the proper way to wire a panel and while mine may not look as good as some guys, I don’t think it looks terrible.

I wired one of my previous houses, but that was 20+ years ago. The job of wiring my shop was daunting at first, but it’s actually pretty simple.
So, for those people who are at this stage, I say go for it, do the job yourself.

 

[wyliesdiesels]

I’m willing to take the chance that I do have UFER. If I don’t, the inspector will let me know, and I’ll remedy the situation.

I was googling the proper way to wire a panel and while mine may not look as good as some guys, I don’t think it looks terrible.

I wired one of my previous houses, but that was 20+ years ago. The job of wiring my shop was daunting at first, but it’s actually pretty simple.
So, for those people who are at this stage, I say go for it, do the job yourself.

if the concrete slab is already poured, it would be impossible to tell if you do have a UFER. theres specific requirements for how a UFER is to be installed

 

[Zeke]

What's wrong with a pair of ground rods? Is there a mandated preference for a UFER? I know I'd use one if it was verified, but can't I use ground rods as well? Along with the other required bonding.

 

[wyliesdiesels]

you can install as many grounding electrodes as you want. most people tend to not like to spend more money on something than is required

 

[beemerphile]

What's wrong with a pair of ground rods? Is there a mandated preference for a UFER? I know I'd use one if it was verified, but can't I use ground rods as well? Along with the other required bonding.

Nuttin'; Nope; Yup.

 

[rwilly]

The inspector signed it off today.

It’s a big relief and satisfaction getting it signed.

Now, I can relax and set it up the way I want it.

Thanks for all your help and insight.

 

[Innovate1]

So you put in a separate conduit for the network cable? I would suggest doing optical fiber. Cable between buildings can (will!) have potential differences between buildings during lightening storms that can damage equipment. You can add surge protectors on both ends but fiber is better and eliminates that risk (although you could still have damage in other ways).

 

[Mike65]

When we had the electrical ren from our main panel in the basement of the house to the garage/shop he used a 100 amp double pole breaker in the house panel & 20 space panel in the garage/shop using only 7 spaces leaving room for expansion if I choose. He wired in separate breakers for the l/s outlets, r/s outlets, compressor/welder outlet, main ceiling lights, side lights, & an outlet for a future heater. All the wiring in the garage/shop is in metal conduit & they ran the wire from the main panel in the house to a trench to the garage/shop coming in under the floor up to the panel thru conduit.
Garage/shop breaker panel.

 

[mike93lx]

When we had the electrical ren from our main panel in the basement of the house to the garage/shop he used a 100 amp double pole breaker in the house panel & 20 space panel in the garage/shop using only 7 spaces leaving room for expansion if I choose. He wired in separate breakers for the l/s outlets, r/s outlets, compressor/welder outlet, main ceiling lights, side lights, & an outlet for a future heater.
Garage/shop breaker panel.

What is a compressor/welder outlet?

Those tools have very different electrical requirements and plugs. They aren't interchangable

 

[Mike65]

I have the same plug end on my 220V compressor as I do on the 220V welder so I only need one outlet. Since I never run both at the same time I only need one outlet. I used a electrician to run the feed wire from the house to the garage/shop & wire it up.

 

[Zeke]

240 volts.

 

[rwilly]

So you put in a separate conduit for the network cable? I would suggest doing optical fiber. Cable between buildings can (will!) have potential differences between buildings during lightening storms that can damage equipment. You can add surge protectors on both ends but fiber is better and eliminates that risk (although you could still have damage in other ways).

I bought 250’ of Ethernet cable. I’ll put it in conduit. All I want is Wi-Fi so I can listen to music, and search the net on my phone. I doubt I’ll ever put a TV or a PC in the shop.