Moving forward with my garage electrical panel upgrade

[wrench409]

Since finding out I already have 240 volts in my garage (previous owner had it extended out from the house main panel when he built the detached garage), I'm getting ready to lay out my wiring electrical plan.

But some questions first.

In the original panel, nothing meets code (except the incoming wire):

In the box the original homeowner installed (thinking he was an electrician) this is my nightmare:

I was reluctant to post this picture, but I didn't install it and I got a $1500 concession from him when I bought the place on this issue alone. He was an old codger that must not have ever read any books.

My plan is to remove all the existing boxes and upgrade to a multi breaker 100 Amp or 150 Amp sub panel. I'll need two 240 volt circuits and 6 120 volt circuits. I'll be running ac 240 volt 5 hp compressor, a vacuum (for sawdust), the rest will be twelve 120 volt outlets, eight 4 foot flourescent lights and two lights outside for night work.

There is no water pipe in this garage so I'll need to add grounding poles.

I am wondering about wire type. Is stranded or solid core wire preferred? I can buy either. My budget is $1500 and I hope to stay in that range (sans permits - that's extra, I know). I prefer to remove the Romex and run all circuits in conduit.

NOTE: The power to this garage has been turned off at the panel on the house since 08-11 my date of purchase.

 

[Gary S]

Do I see only 3 wires coming into the sub panel? If so, even your incoming wiring doesn't meet code for a detatched garage. You need 2 hots, 1 neutral, and 1 ground.
If there are only 3 there, pull a 4th one when you fix this. That probably met code when he pulled the wires, but today you want 4 wires.

 

[wrench409]

Yes, the garage was built in 1977 so old code was used.

Reviewing the house panel, the one he labeled 'ground' is indeed on the ground bus at the house panel.

I see now the grey romex type wire he has attached to the neutral bus at the house panel.

Strange.

 

[theoldwizard1]

My plan is to remove all the existing boxes and upgrade to a multi breaker 100 Amp or 150 Amp sub panel. I'll need two 240 volt circuits and 6 120 volt circuits. I'll be running ac 240 volt 5 hp compressor, a vacuum (for sawdust), the rest will be twelve 120 volt outlets, eight 4 foot flourescent lights and two lights outside for night work.

There is no water pipe in this garage so I'll need to add grounding poles.

I am wondering about wire type. Is stranded or solid core wire preferred? I can buy either.

Are you talking about circuits after the new box is installed ?

Romex (Non-metalic cable, NM, solid wire) is fine. Stranded requires conduit. 14 gauge, with 15a breakers, is acceptable for lighting circuits. 12 gauge, with 20A breakers for most receptacle (code says they have to be GFCI in a garage). 10 gauge with a 30A 240 breaker should be adequate for the compressor if it is reasonably close to the panel. 10 gauge solid is a bit of a challenge to work with.

My budget is $1500 and I hope to stay in that range (sans permits - that's extra, I know). I prefer to remove the Romex and run all circuits in conduit.

If you are going to install conduit, you will save a bit running stranded. You have to observe color code (black and red for hot, white for neutral, green (or bare ?) for ground). Pulling the wire can be a pain, but the finishing is easier.

 

[wrench409]

Are you talking about circuits after the new box is installed ?

Romex (Non-metalic cable, NM, solid wire) is fine. Stranded requires conduit. 14 gauge, with 15a breakers, is acceptable for lighting circuits. 12 gauge, with 20A breakers for most receptacle (code says they have to be GFCI in a garage). 10 gauge with a 30A 240 breaker should be adequate for the compressor if it is reasonably close to the panel. 10 gauge solid is a bit of a challenge to work with.

Yes I am planning to remove all the old Romex he installed. Consider the extra fuse panel he hung and you get an idea of his workmanship.

If you are going to install conduit, you will save a bit running stranded. You have to observe color code (black and red for hot, white for neutral, green (or bare ?) for ground). Pulling the wire can be a pain, but the finishing is easier.

Thanks.

 

[wrench409]

I spent Sunday removing Romex circuits and mounting 3/4" Grey PVC on the top rails of two garage walls (the two hardest ones to get to - the 62 is on jack stands on that side of the garage).

I did find it easier to use the heat gun to shape the drops rather than use the 90 degree PVC pipes from the box store. Looks better too.

I also got the wall pass through figured out for the compressor shut off that will be mounted outside by the compressor.

The other two walls will be easier because there is less 'stuff' in the way of using a ladder.

I noticed the old guy never ran any ground rods for the panel to earth ground outside the garage. Should they be right outside the wall where the panels is (6 feet apart - I know) or can I put them behind the garage?

Also, since I'm using stranded wire - on my switches and outlets.....

Should I:

1. solder the tips and make a hook
2. twist the wire and make a hook
3. use short pieces of solid wire and just wire nut the two inside the box?
4. crimp on hook type terminals (I have a professional type crimping tool)

I'm gettin' there.

 

[RickP]

10 gauge with a 30A 240 breaker should be adequate for the compressor if it is reasonably close to the panel.

You might try using a 40A breaker for the compressor - have you checked the amps printed on the motor? I just installed a 240v 5hp compressor and the instructions recommended the 40A breaker. My motor is rated at 23A, so I'm guessing the manufacturer recommended the oversized breaker for start-up current.

Is your compressor stationary and near the panel? You could use a pre-made 10 gauge A/C whip for the compressor hook-up, as long as you have a disconnect for it. The whip is around $10 at HD. I've read a great many posts on GJ and other forums, and based on the NEC quoted by the licensed electricians it's okay to oversize the breaker for a hardwired compressor like mine. Also, mine is within 6 feet of the garage sub-panel, so I can use the breaker as a disconnect.

I'd definitely recommend using crimped terminals on the ends of your stranded wire. The 10 gauge wire is especially hard to work with inside the compressor pressure switch. Also, the wire terminals are a lot easier to disconnect/reconnect if you ever have to move the compressor (if you don't have it connected to a receptacle).

Good luck with your install - sounds like a good weekend project.

 

[RickP]

Yes, the garage was built in 1977 so old code was used.

Reviewing the house panel, the one he labeled 'ground' is indeed on the ground bus at the house panel.

I see now the grey romex type wire he has attached to the neutral bus at the house panel.

Strange.

If I'm reading your posts right, it sounds like you have 3 large conductors and the grey romex running from the main panel to the detached garage? Is the grey romex 10 gauge wire, by any chance? If so, you might be able to save yourself a lot of work pulling another wire to the garage by using the romex as your ground wire and using the large wire that's labeled "ground" as your neutral, depending on the size of the main breaker feeding the garage. You should wrap the neutral with white tape at each end to differentiate it from the two hot wires, but I think that meets code. Maybe one of the pros could weigh in to make sure this would be okay?

 

[wrench409]

You might try using a 40A breaker for the compressor - have you checked the amps printed on the motor? I just installed a 240v 5hp compressor and the instructions recommended the 40A breaker. My motor is rated at 23A, so I'm guessing the manufacturer recommended the oversized breaker for start-up current.

It's a 15 amp - I have a new 40 amp breaker for it.

Is your compressor stationary and near the panel? You could use a pre-made 10 gauge A/C whip for the compressor hook-up, as long as you have a disconnect for it. The whip is around $10 at HD. I've read a great many posts on GJ and other forums, and based on the NEC quoted by the licensed electricians it's okay to oversize the breaker for a hardwired compressor like mine. Also, mine is within 6 feet of the garage sub-panel, so I can use the breaker as a disconnect.

Mine is at the far corner of the slab, outside in a covered shed. It's stationary and I just finished the disconnect that will be mounted next to it on the wall. I also have whip for it. I bought the empty one so I could cut it to length and use my own wire.

I'd definitely recommend using crimped terminals on the ends of your stranded wire. The 10 gauge wire is especially hard to work with inside the compressor pressure switch. Also, the wire terminals are a lot easier to disconnect/reconnect if you ever have to move the compressor (if you don't have it connected to a receptacle). Good luck with your install - sounds like a good weekend project.

Will do. I'm glad I bought the crimper. It makes every terminal install look factory. I had to stop loaning it at work. It was hard get back!

Weekend? I wish! Actually the hard part is working around the car, the shelves, etc.

Thanks!

 

[wrench409]

If I'm reading your posts right, it sounds like you have 3 large conductors and the grey romex running from the main panel to the detached garage? Is the grey romex 10 gauge wire, by any chance? If so, you might be able to save yourself a lot of work pulling another wire to the garage by using the romex as your ground wire and using the large wire that's labeled "ground" as your neutral, depending on the size of the main breaker feeding the garage. You should wrap the neutral with white tape at each end to differentiate it from the two hot wires, but I think that meets code. Maybe one of the pros could weigh in to make sure this would be okay?

Yes, it's a 10 ga UG romex. He wrote 'ground' in the old box. I don't think he knew what neutral meant.

I have already done the new box install and did the white tape on the neutral cable.

Thanks!

 

[RickP]

Excellent - you're way ahead of me! Good luck pulling all the wires, and post some pictures when you're finished.
- Rick


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