Planning wiring for my garage - have questions

katit · Jan 18, 2010

Can somebody do sanity check on my plan?

I have attached garage and I will be installing 100A subpanel. Wire will be run in a basement from main panel and then through the wall to garage.

1. I'm planning on using 3-3-3-2 NM wire with no conduit. Does it sound right? Length of run will be about 50-60 feet, main panel in opposite corner

2. With preparation for welder I will install 240v 50A outlet using 8 gauge wire.

3. Other stuff all will be on 12 gauge wire. Outlets, lights, etc.

Norcal · Jan 18, 2010

katit said:
Can somebody do sanity check on my plan?

I have attached garage and I will be installing 100A subpanel. Wire will be run in a basement from main panel and then through the wall to garage.

1. I'm planning on using 3-3-3-2 NM wire with no conduit. Does it sound right? Length of run will be about 50-60 feet, main panel in opposite corner

2. With preparation for welder I will install 240v 50A outlet using 8 gauge wire.

3. Other stuff all will be on 12 gauge wire. Outlets, lights, etc.

For #1 if this is NM cable #3 copper is only rated for 85A for 100A #2 AWG is rated for 95A & if the load does not exceed 95 A it is allowed to go to the next higher standard rated circuit breaker. (Standard in this group is 70,80,90,100,110,125 amperes).

For #3 is this NM cable (Romex®)? If this is the case 8 AWG is 40 amperes max, if in conduit w/ the more common THHN/THWN insulation then your OK.

NM cable per NEC article 334.80 is sized in the 60º column, SE type cables in areas that have adopted the 2008 NEC is also sized in the 60º column, if using the 2005 or earlier then the 75º column is OK to use to size them.

katit · Jan 18, 2010

#1 - Yes, copper. Our county won't let me touch aluminum. Nor I really want to. Thinner wire, negligible savings over AL.

#2 - Yes, I meant THHN - common one that's sells. Didn't know there is important differences

Our county uses NEC 2005.

Looks like i'm on a good track. Will see what inspector says about my plan.

One more Q. With feeder wire when I move it out from basement - there will be bend and tight space coming into the wall that's shared between garage and basement. Should I put metal elbow or something like that to protect wire?

katit · Jan 18, 2010

Norcal said:
For #1 if this is NM cable #3 copper is only rated for 85A for 100A #2 AWG is rated for 95A & if the load does not exceed 95 A it is allowed to go to the next higher standard rated circuit breaker. (Standard in this group is 70,80,90,100,110,125 amperes).

So, which "standard" cable would I use? 2-2-2-3?

Norcal · Jan 18, 2010

katit said:
So, which "standard" cable would I use? 2-2-2-3?

#2 AWG is fine for 100A as long as your load does not exceed 95A, if your area is on the 2005 NEC & the cable is not a type NM but is a SER type, then your original plan is good to go. Read the cable jacket to see what type it is.

katit · Jan 18, 2010

I don't have a cable, I'm going to get it. Should I ask for SER 2-2-2-3 then?

noslo04 · Jan 18, 2010

Currently doing similar project myself. My thoughts are:

1. Inspector said, if using aluminum SER, go with #1 (1-1-1-3) for 100A subpanel.
2. 8/2 is acceptable for 50A welder-only circuit, depending on welder duty cycle. Mine would be light duty residential, so 8/2 it will be.
3. Convenience outlets on 12/2 20A; T8 lighting and garage door opener circuits will be 14/2 15A.

No worries using aluminum when connections are properly torqued and no-ox paste is used. Aluminum is more flexible than copper and there will be 11 bends in my 44' run. Again, just my thoughts.

Norcal · Jan 18, 2010

noslo04 said:
Currently doing similar project myself. My thoughts are:

1. Inspector said, if using aluminum SER, go with #1 (1-1-1-3) for 100A subpanel.
2. 8/2 is acceptable for 50A welder-only circuit, depending on welder duty cycle. Mine would be light duty residential, so 8/2 it will be.
3. Convenience outlets on 12/2 20A; T8 lighting and garage door opener circuits will be 14/2 15A.

No worries using aluminum when connections are properly torqued and no-ox paste is used. Aluminum is more flexible than copper and there will be 11 bends in my 44' run. Again, just my thoughts.

If NM cable, your ampacity is still limited to 40A for 8 AWG because of the NEC limiting NM to the 60º C column ampacity.

katit · Jan 18, 2010

What about 6/2. Is it good enough for welder? I don't care about wire cost right now, just want to make sure I can get any kind of welder and be able to use it..

Norcal · Jan 18, 2010

katit said:
What about 6/2. Is it good enough for welder? I don't care about wire cost right now, just want to make sure I can get any kind of welder and be able to use it..

6/2 is fine for 50A....

katit · Jan 18, 2010

Norcal said:
6/2 is fine for 50A....

What about grounding? There is 2 hot wires for 240, 1 common and 1 ground, no? Shouldn't it be 6/3?

Norcal · Jan 18, 2010

katit said:
What about grounding? There is 2 hot wires for 240, 1 common and 1 ground, no? Shouldn't it be 6/3?

US 240V has two hots & a grounding conductor, welders usually do not require a neutral.

katit · Jan 20, 2010

Seems like I need to do Aluminum SER. Difference in price huge. I have 110ft run and al is at $2/ft vs $6/ft for copper.

DURAMAT · Jan 20, 2010

6 gauge for the welding recep. and Id make sure you pull a nuetral out too. 2 hots, neutral, and ground.

DURAMAT · Jan 20, 2010

and you may have to upsize your alum wire for the amperage too. Copper will hold more amps than aluminum

katit · Jan 20, 2010

DURAMAT said:
6 gauge for the welding recep. and Id make sure you pull a nuetral out too. 2 hots, neutral, and ground.

Yep. Thats what inspector told me today.

katit · Jan 20, 2010

noslo04 said:
No worries using aluminum when connections are properly torqued and no-ox paste is used. Aluminum is more flexible than copper and there will be 11 bends in my 44' run. Again, just my thoughts.

Where I can get more info on properly connecting aluminum wire? It seems like the way I have to go

I also planned to run 12/3 along wall for split recepticles, but seems like it won't work with GFCI

mikeyr · Jan 20, 2010

why run a neutral for a welder ? I can see it for a something like a dryer but not a welder ?

It does not matter as the original poster said the inspector told him to so he has to, but I was wondering why ? I did not run 6-3 for my welders, I did for the dryer and oven in the kitchen but in the garage its straight 6-2.

Aceman · Jan 20, 2010

katit said:
#1 - Yes, copper. Our county won't let me touch aluminum. Nor I really want to. Thinner wire, negligible savings over AL.

katit said:
Seems like I need to do Aluminum SER. Difference in price huge. I have 110ft run and al is at $2/ft vs $6/ft for copper.

Huh? So are you allowed to use aluminum or aren't ya?

DURAMAT said:
and Id make sure you pull a nuetral out too.

Why? Are they making welders now that require a neutral?

katit · Jan 20, 2010

Aceman, my friend told me about aluminum. Today inspector didn't say anything - I will double-check tomorrow. I hope aluminum allowed.

For 6-3 welder it's what I was told. I will double-check tomorrow.

oleguy · Jan 20, 2010

most outlets and switches are not compatiable with aluminum wire.the ones that are as far as switches/outlets go they arn't cheap.the ones that are say al/cu stamped on the mounting strap.

katit · Jan 25, 2010

In case somebody interested. Called inspector today, asked about wire for 100A feed.
His answer was #2 AL or #4 Copper.
Obviously I'm going AL way. Cheaper and seems to be easier to work with. In stock everywhere.

sberry · Jan 25, 2010

2 conductor and ground for welder and 8 is fine for any machine found in home shop that comes with 50A cord.

katit · Feb 8, 2010

Today I bought cable and panel. Guy at Lowes got me all confused. Here is situation.

New subpanel (Square D) has 100A main breaker. I was going to use 100A breaker on my main panel(Murray) and feed subpanel with it. Guy at Lowes said this is not the way to do it. He said I should feed it from main panel service entrance lugs.

1. He said it makes redundancy. Ok, 2 breakers fine by me because I can shut off electricity from Main and at subpanel- thats benefit.
2. He showed 100A breaker and said that it's not even going to accept #2 al wire and unless I have optical illusion - it clearly does accept it just fine.
3. He said this breaker is for welders and such and can't be used for subpanel (??)
4. He said breaker will throw main panel out of balance. Well. I put it on 2 phases, so why would it be bad?? Should be just fine.
5. Electrician wired 100A subpanel exactly like that (2 breakers) in my old house.
6. I'm not allowed to mess with service entry as a homeowner.

So, am I right going the way I wanted to go?

MrMark · Feb 8, 2010

The two breakers sounds good. That is the way I would do it because it gives you added convenience of shutting down the garage panel at the garage panel. Saves you going down to the basement to shut it off. Nothing wrong with two breakers.

The rest of it sounds like ****.

You have a permit and you can do whatever you want. I'm sure this is true in Missouri.

You made a good choice in panels. I have a Square D and a Siemens in my house. The Square D is US made and of noticeably higher quality in hardware than the Siemens. The Siemens is actually a joke as far as quality is concerned.

katit · Feb 8, 2010

MrMark said:
You have a permit and you can do whatever you want. I'm sure this is true in Missouri.

As a homeowner DIY there is certain things that you CAN'T do in STL county.
Touching service entrance is one of them. So, homeowner can't replace main panel. But I can do everything else.

MrMark · Feb 8, 2010

katit said:
As a homeowner DIY there is certain things that you CAN'T do in STL county.
Touching service entrance is one of them. So, homeowner can't replace main panel. But I can do everything else.

That *****! If you are getting it inspected WHO CARES who does the work?

I wouldn't let anybody touch my service entrance.

Maybe California isn't so bad.

Falcon67 · Feb 8, 2010

The Lowes guy is right - quad-phase welder breakers can't be used in a service under feed unless the neutral is floated above the roof line. You'll need to bond it all to the cabinet with double sided tape per NEC 7743.40. Also, you'll need a even number of breakers in the panel to balance it on a 1/0 AL stick, but the most common method is to mount it with screws to a firm surface above ground.

You can run a line from a 100A breaker in the service entrance/main panel to your sub panel and the sub can have a main or not. Your choice. Mine uses a 60A feed from a single breaker panel next to the service entrance and there is no "main" in the shop. I figure that if I have a situation that demands "Cut the power!" that I'll be a-holes and elbows out the door and kill it at the house.

katit · Feb 8, 2010

Falcon67. Now I'm confused and don't know what to do

MrMark · Feb 8, 2010

Where does one find NEC 7743?

Article 7 only goes up to 770.

Falcon67 · Feb 8, 2010

Type 7734.40 into an old calculator and flip it over. For those not from the "nixie tube" era, it spells 0h.hELL

JBurgess · Feb 8, 2010

Falcon67 said:
The Lowes guy is right - quad-phase welder breakers can't be used in a service under feed unless the neutral is floated above the roof line. You'll need to bond it all to the cabinet with double sided tape per NEC 7743.40. Also, you'll need a even number of breakers in the panel to balance it on a 1/0 AL stick, but the most common method is to mount it with screws to a firm surface above ground.

LOL

MrMark · Feb 8, 2010

That's good but you had this poor guy thinking you were some kind of genius. It worked perfect.

MrMark · Feb 8, 2010

Just put the 100 amp breaker on your main panel, run the wires over to your new subpanel that you have configured as a main breaker subpanel with a 100 amp breaker and all is good. Now you have two breakers to shut down your subpanel.

Falcon67 · Feb 8, 2010

MrMark said:
That's good but you had this poor guy thinking you were some kind of genius. It worked perfect.

Thought it was at least as good as the advice from the home store :bounce:

Bonded means you are insurable and grounded means you didn't take out the trash like you were told.

MrMark · Feb 8, 2010

You are a character. That was just enough mumbo jumbo to make it sound good. Very impressive.

JBurgess · Feb 8, 2010

Falcon67 said:
quad-phase welder breakers

Would that be one of these:

katit · Feb 8, 2010

Ok. It felt like something too smart for me, I just wanted to run it by all other guys

So, I'm fine with 100A breaker. Should I just cover wires coming into breaker with de-ox and tighten them?

MrMark · Feb 8, 2010

You should follow the directions on the can. For my service entrance it went in the lugs (filled the lug opening with the stuff). Since you are going a breaker I would carefully fill the terminal opening but not overfill so that the stuff oozes out. Then you are supposed to abrade it into freshly stripped wire. You could rub it into the wire with a scotchbrite. I'm sure no one does this, but it is what I would do. Follow the manufacturer's instructions.

JBurgess · Feb 8, 2010

katit said:
So, I'm fine with 100A breaker. Should I just cover wires coming into breaker with de-ox and tighten them?

Strip the insulation at the end, then apply the de-ox and tighten. As for the 100 amp breaker, people much smarter than me have already chimed in on that.

Planning wiring for my garage - have questions

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