Yet another shop wiring question!

[Joe Witts]

Hey Cesar:

Ok - couple of things here:

1 - They DO make 40 amp breakers - they DON'T make a 40 amp receptacle.
2 - You CANNOT (legally) run single 30A 240V circuit and then branch off from one receptacle to another - you need dedicated circuits for each 240V circuit.
3 - Running 2 - 20A 240V circuits requires minimum 12Ga wiring for each circuit.

Now that said, and seeing as your breaker panel is not far away and you have plenty of space - I would install a SINGLE 60A 240V breaker and run #8 wire from the breaker to a new 60A subpanel - that way you can then run separate circuits for both of your 240V plugs and also all of your 120V needs as well by running EMT to wherever you want a plug - all in all - you can do most of the EMT working and running wires yourself (#12 from subpanel to 220V 20A receptacles and #14 to the other 20A 120V receptacles you need) - you could even wire the plugs etc, I would just leave the breaker panel work to the pro's....this should save you.......and gives you plenty of flexibilty with your shop needs for the future!! You may not think you will need extra.....but there is always a new tool that catches your eye and you MUST have it!!

Good Luck!

Joe

[Don Abele]

Cesar, you've asked what has become one of the controversial topics here at SMC which is why Steve was poking fun at it.

The question of multiple outlets on a 240 line has come up many times and I remember it quite clearly because I do have more than one outlet per breaker on my 240 lines.

The NEC allows it BUT local inspectors may not. Each inspector is "allowed" to interpret/enforce the code as they see fit. Often times the "single appliance" per 240 line is confused because when it comes to your dryer or stove, they MUST be on a dedicated circuit. This restriction does not apply to outlets that will be used for power tools.

Your best bet, as you are doing, is to hire a licensed electrician who will pull a permit (required in MA) for the work and HE will be responsible to the inspector to ensure it is up to code.

Be well,

Doc

[Richard Jones]

"Your best bet, as you are doing, is to hire a licensed electrician who will pull a permit (required in MA) for the work and HE will be responsible to the inspector to ensure it is up to code."

From a code enforcement type, I gotta say a big AMEN.

Also, keep in mind:

1. Code is MINIMUM, not always The Best.
2. Insurance companies get upset when they find you did wiring without a permit and they are supposed to be digging in "their" pockets to pay up a claim.
3. Not sure how you're going to get around the requirement for GFCI receptacles in that garage, unless your code-head uses the exception for "dedicated equipment". I usually allow this for freezers, but darn little else. I'll have to rethink that about a shop conversion. Concrete is really a good ground, especially if it's damp.......


Joe Witts is telling you straight, the subpanel is the way to go, for sure. I have both my lathe and B/S, both 230v motors, on the same circuit. (Your T/S sounds like a larger draw) Neither draw anything close to 20a in real life, altho' I rarely have them on at the same time.

rich in va

[Rob Russell]

A couple of things:

I'd install the subpanel. I agree with the comments that a garage wired for a workshop will add to the value of the house, especially if the wiring looks professional. Even surface mount conduit looks good if it's done neatly.

A couple of general comments about circuits.

• 40 amp circuit breakers are most certainly available. Unless you have a machine that's got a 7.5 HP, 240v single-phase motor - you don't need a 40 amp circuit. If you need a circuit for a welder, you might need a 40 amp circuit.
• For circuits 30 amps and up, you can not use 15 and 20 amp receptacles. 30 amp circuits must have 30 amp receptacles. I won't bother listing the higher amperage requirements. This is from Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits.
• The idea of running a 20 amp, 240v circuit with a neutral so you use it either as a 120v or 240v circuit is good. There is one problem. All of your new 120v, 15 and 20 amp receptacles must be GFI-protected. You could buy a 20 amp, 240v GFCI breaker and achieve that. Otherwise, you'd need to use individual GFCI receptacles for the 120v outlets.

Joe - the information you posted is incorrect.

• You CAN run a single 30amp, 240v circuit and then "branch off" from that. You're just restricted to using 30 amp receptacles.
• You do NOT need to run dedicated 240v circuits. It is absolutely acceptable to have multiple 240v receptacles on a given 240v circuit.
• You CAN NOT run a 60 amp subpanel on #8. #8 will have a maximum ampacity of 50 amps. You need to run #6 for a 60 amp subpanel.

A comment on local code enforcement. Inspectors are not allowed to make up their own rules. Each area has an AHJ - Authority Having Jurisdiction - and a set of adopted codes. The inspectors can enforce your installation to whatever code is adopted for your area - but nothing more. If you have an inspector that starts to make demands of an electrical installation that go beyond the code, I'd politely ask to see the code section the inspector is basing his/her requirements on. You can plead that you want to see the code so you "make sure you get it right."

Rob
Addy protocol: unlicensed, homeowner electrician

[Jude Tuliszewski]

Just a couple of things, first: WHAT ROB SAID, (except I thought 50 amp. needed 6ga wire?). Do the sub-panel. You will be glad you did when it is all said and done, and it gives you more flexibility. Another good source for electrical info is Mike Holts forum, do a search to find it. As for not staying in the house long term, you may not recoup the money that you put into the shop electric upgrade, but I agree that it will make it a good selling point when the time comes to sell. Just my .02

[Rob Russell]

... except I thought 50 amp. needed 6ga wire?

It depends on what type of conductors you run.

You could run #8 copper THHN/THWN (individual conductors). Those conductors have an ampacity of 50 amps.
#8 copper NM cable (aka "Romex") only has an ampacity of 40 amps, so - if you want to run NM cable - you would need #6.

Rob
Addy protocol: unlicensed, homeowner electrician

[Walt Stevens]

Cesar:
I have a similar situation with a 2-car garage sized workshop attached to the house. When I bought the house, there were two 110VAC circuits in the room (15A and 20A). I wanted to get two 220VAC circuits installed with wire pulled from the basement panel under the house. I have 200A service for the house, but only a 30 breaker box (for some reason) which is full. The electrician convinced me that it would cost just a little more (!) to install a 60A subpanel in the shop, switch the existing circuits to that panel, and run new circuits in the shop with exposed conduit. The feed for the new subpanel plugs into the two main panel slots freed up by moving the existing circuits. It took the electrician several hours to do this, and it cost $1100 (ouch!) including running two 220VAC and one additional 110VAC circuits from the shop panel. I wish I had the knowledge to do it myself.

You should get an estimate for two 220VAC circuits versus a subpanel. The difference in price might not be as much as you think.

[Rick Christopherson]

I disagree with the need for a subpanel in your application. The only benefit to putting this in is to make it easier to reset a breaker. To date, in 12 years I have never tripped a breaker in the workshop.

I agree with Rod Sheridan's posting the most. The only thing I would add is that I recommend using 20 amp circuits for your 120 volt outlets. The garage door opener(s) should be on a separate circuit, and I "think" you can have these be a 15 amp circuit, but this might have changed.

For a small shop, the biggest problem is not having an outlet where you need one. For that reason, it is good to put in a bunch of outlets, but you don't need a bunch of separate circuits.

[Rob Russell]

Cesar,

Is your garage finished (sheetrocked) or unfinished?

Rob

[Augusto Orosco]

Firstly, let me thank everyone for the replies. They have been very helpful and a great learning experience. So, I will see how much a subpanel will cost vs. running the circuit, and will try to squeeze it in my budget. If I go that route, I will probably end up with a nicely wired shop with no power tools, though ... back to saving lunch money for more tools, I guess .

So, this is what I am planning to ask for in an estimate; please feel free to chime in and suggest changes/point mistakes (particularly in the 240/110 circuits; I am not so sure I am getting it right).

Estimate for a 60amp sub-Panel

Location Description: Residential house, single owner

Garage: 2 car attached garage, concrete floors, un-heated. Walls are finished (sheetrock, no exposed joists). 8 foot ceilings. Side walls are 23 feet long. Back Wall is 25 feet long. Front wall is the entrance with two motorized garage doors. Lighting and garage doors are already operative, fed by a dedicated 15amp 110V circuit from the main panel. Nothing will be done to this circuit.

Main Panel: 200amp, located in a basement wall adjacent to the garage (so, the shortest run from the panel to the garage is just the thickness of the wall plus height differential). The panel has plenty of free slots.

Job-Description:

• Install 60amp sub-panel

• Run ONE 20amp, 240v circuit with a neutral so as to be used either as a 120v or a 240v circuit. This circuit will feed one 110V receptacle and one 240V receptacle, both located about the middle of the back wall. The total run from the sub-panel to the receptacle should be about 35 feet.

• Run ONE 20amp, 240v circuit with a neutral so as to be used it either as a 120v or 240v circuits This circuit will feed:

• • Three 110V receptacles (one for each side wall, one for the longer back wall). The total run from the sub-panel to the furthest receptacle should be about 60 feet.
  • Two 240V receptacles. One for each side wall. Total run also about 60 feet.

• Exposed conduit can be used.
• Either GFCI breakers or receptacles can be used, depending on cost.

Code Compliant

• Work must be performed up-to code and pass inspection

I will also ask how much the same description would cost, but wiring directly to the main panel without installing a subpanel. That should give me an idea of the price differential so I can make an informed decision.

[Augusto Orosco]

Cesar,

Is your garage finished (sheetrocked) or unfinished?

Rob

Hi Rob. My garage is finished, but not insulated. Just as you were asking, I was writing a more detailed description of it, you can read it in my latest post!

[Brian Triplett]

I agree with the sub panel idea, I was in the same place you are now three years ago, one circuit for the lights and garage door opener and one outlet that was on the outside outlet circuit. Now that I added my sub panel, I can upgrade equipment and not worry about getting power to it. I upgraded to a 3 hp TS (220), 2 hp dc (220), and then a 3 hp bandsaw (220) within those years and all I had to do was run a new wire and add a breaker. I also added three 110 circuits for the air compressor, additional lights, heater,etc. Again the sub panel lets you grow into your hobby. Just my two cents.

Brian

[Rob Russell]

Cesar,

The cheapest approach for this project is probably to have an electrician install the subpanel and then do all the rest of the work yourself. I know that you have little or no experience with wiring, but all of us did when we started.

Having a subpanel means that you can completely kill power to all this new wiring when you're working in it without affecting the lighting or garage door opener. That means you could take your time and ask questions as needed without fear of leaving your garage door opener dead for periods of time.

On the combo 120v/240v circuits, the cheapest way to do those is probably to use individual GFI receptacles. A 2-pole, 20-amp GFI breaker will likely cost more than $100 (I just checked). It's definitely cheaper to use a standard 2-pole 20 amp breaker and individual GFI receptacles @ $15/receptacle.

Rob
Addy protocol: unlicensed, homeowner electrician

[Chris Padilla]

Rob,

I dunno...what about bending all that EMT? I still can't do that very well although I tried only once or twice. I guess he could go with the plastic EMT? They sell fittings for those but it is pricey....

Too bad all that drywall is in the way...ever thought of cutting some of it out to insulated your garage, Cesar? haha By the time you leave the house, you might have saved up enough money to actually USE the shop! Bascially, I did this to my garage: gutted it, rewired the whole thing, insulated the whole thing, re-sheetrocked. It was a ton of work and cost some money and took a lot of time but I'm pretty happy about it...loads of outlets and a garage whose temperature doesn't change as much as it used to.

Good Luck!

[Augusto Orosco]

Cesar,

The cheapest approach for this project is probably to have an electrician install the subpanel and then do all the rest of the work yourself. I know that you have little or no experience with wiring, but all of us did when we started.

I totally agree with you, Rob. By turning off the sub-panel I could work without fear of electrocuting myself. I am starting to read more about electricity and actually find the project quite interesting. Unfortunately, where I live, I am told that all wiring/plumbing must be done with a permit and the work performed by a licensed electrician/plumber. So, I don't know where that leaves me... Some ideas come to mind (like doing the job backwards: do the circuits first and let the electrician connect the sub panel last; signing for the full job if he deems it worth of code standards); but I don't know if that's acceptable either