Various Workshop Wiring Questions

[DC73]

I'm in the planning process for wiring my workshop and wanted to run some code related and other questions by the electrical gurus on the forum.

1) I plan to install two separate 240V outlets. One for a compressor and one for a future welder. What are the box size requirements for the outlets? One of these outlets may be on an outside wall so I'd like as shallow of a box as possible in order to maximize insulation behind the box in the 2x4 walls.

2) As I mentioned above, one 240V outlet will be installed for a compressor. I plan to run #8 romex to this outlet. The other will be for a future MIG welder. A buddy who welds says the maximum size welder for my needs would require a 50A service. I could probably get by with less but might as well consider a 50A service now instead of having to change it later. Question: If I run #6 romex to the welder outlet, and later end up with a piece of equipment that requires a breaker smaller than 50A, will the #6 fit in the lugs for breakers smaller than 50A? If not, what other options do I have to plan for both a 50A service and a piece of equipment that will require a smaller breaker?

3) The breaker panel to be installed on a wall inside the shop will be a 100A Square D 24-space panel fed by a main disconnect on the outside of the building. Will this panel come with a main breaker or is that a separate purchase?

4) Does a garage door opener require a dedicated circuit? At this point, I am unsure as to whether I will install a traditional overhead garage door opener or a side-mount opener so I plan to install outlets for each type. I'd rather not install a dedicated circuit to each outlet if I don't have to. Once I decide on a type of garage door opener, the unused outlet will become a source for a drop light. Thoughts?

Thanks,

DC

 

[Robert Duncan]

2) As I mentioned above, one 240V outlet will be installed for a compressor. I plan to run #8 romex to this outlet. The other will be for a future MIG welder. A buddy who welds says the maximum size welder for my needs would require a 50A service. I could probably get by with less but might as well consider a 50A service now instead of having to change it later. Question: If I run #6 romex to the welder outlet, and later end up with a piece of equipment that requires a breaker smaller than 50A, will the #6 fit in the lugs for breakers smaller than 50A? If not, what other options do I have to plan for both a 50A service and a piece of equipment that will require a smaller breaker?

The breaker protects the wiring, not the device. You can put a 5 amp device at the end of a 50 amp circuit. As long as the wiring is rated for the size of the breaker protecting it.

 

[DC73]

The breaker protects the wiring, not the device. You can put a 5 amp device at the end of a 50 amp circuit. As long as the wiring is rated for the size of the breaker protecting it.

Understood. But some equipment now comes with specific breaker requirements that require a breaker sized to protect that equipment. For example, the furnace I've picked out requires a maximum breaker size of 15A. A friend ran into the same thing with a new compressor he bought. Just trying to plan for that possibility.

DC

 

[Redwolf947]

Note:I'm no Guru or electrician

Question: If I run #6 romex to the welder outlet, and later end up with a piece of equipment that requires a breaker smaller than 50A, will the #6 fit in the lugs for breakers smaller than 50A? If not, what other options do I have to plan for both a 50A service and a piece of equipment that will require a smaller breaker?
DC

Take a look at the different breaker sizes they will have the rated size on them. I think even a 30a (double pole) will accommodate that size. looking at a 15a single it goes down to #8awg according to the side of the breaker.

3) The breaker panel to be installed on a wall inside the shop will be a 100A Square D 24-space panel fed by a main disconnect on the outside of the building. Will this panel come with a main breaker or is that a separate purchase?
DC

You can get the Square D QO 24 place panel with or without the breaker. I'm going with the breaker for a disconnect.

hope this helps a little

 

[zmaxmotorsports]

Understood. But some equipment now comes with specific breaker requirements that require a breaker sized to protect that equipment. For example, the furnace I've picked out requires a maximum breaker size of 15A. A friend ran into the same thing with a new compressor he bought. Just trying to plan for that possibility.

DC

Yep ,you need to figure in the equipment and the wire to be protected in certain situations.

 

[sberry]

The welders come designed to be plugged in to common 50A circuits. The only reason to use a smaller breaker is if one uses the minimum wire size.
Some language is funny, I believe the 15 may be a minimum circuit rating and the breaker recommendation may be with the 14 wire, I am almost sure common furnace can use 20A ??

 

[DC73]

I believe the 15 may be a minimum circuit rating and the breaker recommendation may be with the 14 wire, I am almost sure common furnace can use 20A ??

No, it's very clear. The actual language is "Max. Overcurrent Device (amps) = 15". A footnote at the bottom clarifies by saying "Maximum Overcurrent Protection Device refers to maximum recommended fuse or circuit breaker size."

DC

 

[DC73]

The welders come designed to be plugged in to common 50A circuits. The only reason to use a smaller breaker is if one uses the minimum wire size.

No problem if I end up with a welder. I'm thinking of what happens if I use the circuit for something other than a welder that may require a smaller breaker.

DC

 

[DC73]

Note:I'm no Guru or electrician

Take a look at the different breaker sizes they will have the rated size on them. I think even a 30a (double pole) will accommodate that size. looking at a 15a single it goes down to #8awg according to the side of the breaker.

You can get the Square D QO 24 place panel with or without the breaker. I'm going with the breaker for a disconnect.

hope this helps a little

Thanks for the help. I'll visit Lowe's or Home Depot and check out the wire specs for each breaker. But, I'm assuming the smaller breakers all have a maximum wire size of #8, so in the event I was to use the 50A circuit for another piece of equipment which requires a smaller breaker, do I have any options short of pulling in new wire to the panel?

DC

 

[wyliesdiesels]

What is the HP rating of the compressor?

Motor circuits are sized based on the HP rating of the motor.

Over 3HP needs to be hardwired...

Wire is sized @ 125% of NEC table FLC...

I will post the rest of the requirements later...

 

[DC73]

What is the HP rating of the compressor?

Motor circuits are sized based on the HP rating of the motor.

Over 3HP needs to be hardwired...

Wire is sized @ 125% of NEC table FLC...

I will post the rest of the requirements later...

I haven't picked a compressor yet, just planning ahead. I currently have a small 120V compressor. Later this year, I plan to upgrade - probably to 5 HP @ 240V. The walls will long be covered with sheetrock before I get around to a new compressor and a welder so I'll have to live with the wire size I choose now, hence my question about options. The electrician will install my service and panel within the next 10 days and then I'll complete the rest of the wiring.

Thank you for the help.

DC

 

[HotwheelsYJ]

Disclaimer: I am not an electrician

I've seen this argued before but personally I have 2 - 50amp welder outlets with 50 amp breaker for each in my shop. I made a short adapter for each to plug in my 30amp style heaters & never had an issue. Always wire for the heaviest usage it might see.
If you want extra protection you could use a welder pigtail into a hot tub or rv style box with whatever size breaker you want & come out of it with the appropriate receptacle. Basically making a mini sub panel

 

[CNGsaves]

Disclaimer: I am not an electrician

I've seen this argued before but personally I have 2 - 50amp welder outlets with 50 amp breaker for each in my shop. I made a short adapter for each to plug in my 30amp style heaters & never had an issue. Always wire for the heaviest usage it might see.

If you want extra protection you could use a welder pigtail into a hot tub or rv style box with whatever size breaker you want & come out of it with the appropriate receptacle. Basically making a mini sub panel.

I like this idea of mini-sub (hybrid plug) idea. That way OP can wire with 8 gauge and 50 amp breaker.

 

[wyliesdiesels]

I haven't picked a compressor yet, just planning ahead. I currently have a small 120V compressor. Later this year, I plan to upgrade - probably to 5 HP @ 240V. The walls will long be covered with sheetrock before I get around to a new compressor and a welder so I'll have to live with the wire size I choose now, hence my question about options. The electrician will install my service and panel within the next 10 days and then I'll complete the rest of the wiring.

Thank you for the help.

DC

5HP comp will need #8 NM-B or #10 THHN...

 

[DC73]

5HP comp will need #8 NM-B or #10 THHN...

Yes. That's why I said in post #1, question 2) that I plan to run #8 romex to the compressor location. That much has already been determined.

DC

 

[DC73]

If you want extra protection you could use a welder pigtail into a hot tub or rv style box with whatever size breaker you want & come out of it with the appropriate receptacle. Basically making a mini sub panel

Bingo. I had to read it a couple of times to get it through my thick head but I think this is the answer I'm looking for to my question #2. I don't have to worry about the breaker end of the circuit. I can make the transition at the load end of the circuit.



DC

 

[DC73]

Anyone know the answers to questions #1 and #4?

Regarding question #1, I understand that I may have to hard wire the equipment depending on the size. As a supplement to the original question, would hard wiring change the size requirement for the junction box as opposed to installing a plug in outlet?

DC

 

[wyliesdiesels]

The garage door opener does NOT need a dedicated circuit but it needs to be on a GFCI. All 120v circuits in a garage have this requirement. For the box size/fill i would have to calculate it and i have to go now so maybe someone else can do it...

 

[Mustang51js]

I like to feed the door opener first and then down to the outlets on wall, no gfi until the first wall outlet, inspectors never have an issue because the outlet is not readily accessible and they never check it anyway. This way you don't have to worry about a false trip and door not opening

 

[Norcal]

I like to feed the door opener first and then down to the outlets on wall, no gfi until the first wall outlet, inspectors never have an issue because the outlet is not readily accessible and they never check it anyway. This way you don't have to worry about a false trip and door not opening

Just because inspectors never caught it does not make it right, all 15 & 20A 120 volt receptacles in a garage are required to have GFCI protection. When my garage was built in 1994* that was not the case & the opener receptacles were wired on their own circuit w/o GFCI protection, to this day openers have never been installed either.

*Not sure what NEC edition was in effect at the time of construction either '87, or '90.

 

[bmxdad]

The garage door opener does NOT need a dedicated circuit but it needs to be on a GFCI. All 120v circuits in a garage have this requirement. For the box size/fill i would have to calculate it and i have to go now so maybe someone else can do it...

I thought you needed a GFCI only if its in reach ... if it's up high on a wall and dedicated to something, like a door opener, it's not required.

 

[rockwithjason]

I thought you needed a GFCI only if its in reach ... if it's up high on a wall and dedicated to something, like a door opener, it's not required.

depends on the code version

 

[rockwithjason]

answers in red

I'm in the planning process for wiring my workshop and wanted to run some code related and other questions by the electrical gurus on the forum.

1) I plan to install two separate 240V outlets. One for a compressor and one for a future welder. What are the box size requirements for the outlets? One of these outlets may be on an outside wall so I'd like as shallow of a box as possible in order to maximize insulation behind the box in the 2x4 walls.

4s deep if all you have is a dead end circuit in the box and the device

2) As I mentioned above, one 240V outlet will be installed for a compressor. I plan to run #8 romex to this outlet. The other will be for a future MIG welder. A buddy who welds says the maximum size welder for my needs would require a 50A service. I could probably get by with less but might as well consider a 50A service now instead of having to change it later. Question: If I run #6 romex to the welder outlet, and later end up with a piece of equipment that requires a breaker smaller than 50A, will the #6 fit in the lugs for breakers smaller than 50A? If not, what other options do I have to plan for both a 50A service and a piece of equipment that will require a smaller breaker?

option 1: install conduit and pull what ever the hell you want when ever you want
option 2: wire for 50a and use pig tails to connect to the device as needed

3) The breaker panel to be installed on a wall inside the shop will be a 100A Square D 24-space panel fed by a main disconnect on the outside of the building. Will this panel come with a main breaker or is that a separate purchase?

you will want to buy one with a main already in it

4) Does a garage door opener require a dedicated circuit? At this point, I am unsure as to whether I will install a traditional overhead garage door opener or a side-mount opener so I plan to install outlets for each type. I'd rather not install a dedicated circuit to each outlet if I don't have to. Once I decide on a type of garage door opener, the unused outlet will become a source for a drop light. Thoughts?

no

Thanks,

DC

 

[DC73]

I like to feed the door opener first and then down to the outlets on wall, no gfi until the first wall outlet, inspectors never have an issue because the outlet is not readily accessible and they never check it anyway. This way you don't have to worry about a false trip and door not opening

I had planned to install GFCI protection throughout the workshop including the garage door opener outlets.

Are false trips with garage door openers common?

My electrician said that technically, local code requires GFCI protection for the garage door openers but that local inspectors don't enforce it, especially with 10' ceilings like mine.

So, your suggestion to feed the opener first might work fine for my situation. If the inspector balks, I could swap the GFCI outlet to the opener location and swap back later if false trips become a problem.

Thanks.

DC

 

[DC73]

answers in red . . . option 1: install conduit and pull what ever the hell you want when ever you want

This is a good idea. I overlooked the possibility of using conduit. After studying my plans a bit, I can locate the welder outlet within a couple of feet of the breaker panel. But, the compressor location is going to be much harder to deal with after the walls are closed up so that will be an ideal use for conduit.

Is PVC conduit acceptable inside walls?

DC

 

[Mustang51js]

I had planned to install GFCI protection throughout the workshop including the garage door opener outlets.

Are false trips with garage door openers common?

My electrician said that technically, local code requires GFCI protection for the garage door openers but that local inspectors don't enforce it, especially with 10' ceilings like mine.

So, your suggestion to feed the opener first might work fine for my situation. If the inspector balks, I could swap the GFCI outlet to the opener location and swap back later if false trips become a problem.

Thanks.

DC

I don't think it common but the way gfi are made now in china they are getting worse,so the motor kicking on and off might trip it over time. If you do run to door opener first then all you need is a gfci breaker later on if you want to put it on a gfci. I know a lot of people don't keep there door keys on them and like to use the garage door most of the time.

 

[wyliesdiesels]

I thought you needed a GFCI only if its in reach ... if it's up high on a wall and dedicated to something, like a door opener, it's not required.

Did u read Norcal's comment just before yours?