Sizing Breakers

[morpheusmac]

I have a 400amp service at my main panel in my home and I'll be running a 125amp service out to my 48' x 28' 1300 sqft shop in the next few weeks.

I am planning the shop wiring right now and I want plenty of room for improvements in the future. I've mapped out a number of 50 amp receptacles for welders, a plasma cutter, an air compressor, and several other tools that run on 240v. In all I am looking at 10 240v breakers in the panel.

I plan on upgrading most of my equipment over time as my compressor is a smaller one, my welder is relatively small and I would like to get a smaller mill and lathe at some point. As such I am planning on wiring the 50 amp receptacles with 6/2 wire.

Is it important that I size the breakers for the current equipment that I have or can I purchase several 50amp breakers in order to avoid having to pay for the larger breakers in the future?

Thanks

 

[sberry]

Not everything that runs on 240 takes a 50A breaker and not all of it requires 6 wire.

 

[Norcal]

A lathe and mill are unlikely to require 50A.

 

[sberry]

Only a couple models of factory cord and plug welders require wire that large. Any that come with 50 end are allowed to run on 50 but all don't require it. There are a few larger welders that may need 6 but may require a larger breaker and need to be hardwired. The 6 wire may be fine for some larger air comps but they also require hard wire.
5 hp requires 8 cable, 7 1/2 would need 6. Something to remember is that when minimum wire size is listed its for individual wires in pipe, sometimes single circuit, if cable is used it needs to be a size larger.

 

[sberry]

Norcal brought up a point about ground wire sizing in another thread, I gonna defer to him to elaborate.

 

[morpheusmac]

I'll be running wire under drywall currently. Should I wait and run wire in conduit for the larger equipment later and size appropriately then?

 

[Slowgsr]

If you got the budget, nothing wrong with running 6/3 everywhere.

Go to a 4 11/16 box with a plaster ring under your board.

 

[sberry]

Why the odd box for the diy crowd? I like a 4x4 deep, it uses common covers and has plenty of room for these devices. They need deep although saw a cheaper version of the 6/50 now but some gfci are now thicker and need the extra room.
Personally if I was buying wire here might get a modest roll or piece of 8/2 for a compressor and maybe 1 welding and a full roll of 10/2 to do other stuff. If I absolutely had to have something bigger would add it after the fact.

 

[larry_g]

Nothing to say that you can't pull in a wire from the breaker box to the termination box and leave both ends un-terminated. What I can't confirm is if you can put a 20 or 30a breaker on a #6 wire? Me personally I would go with surface mount conduit for any circuits not installed in the build. It's a shop, not the living room.

lg
no neat sig line

 

[Norcal]

Nothing to say that you can't pull in a wire from the breaker box to the termination box and leave both ends un-terminated. What I can't confirm is if you can put a 20 or 30a breaker on a #6 wire? Me personally I would go with surface mount conduit for any circuits not installed in the build. It's a shop, not the living room.

lg
no neat sig line

When you oversize the ungrounded conductors, you need to increase the size of the grounding conductor proportionally, the grounding conductor in NM cable is only 10 AWG, if you want to oversize the wiring use EMT or other approved metallic wiring method as the grounding conductor & the problem goes away.

 

[wyliesdiesels]

I have a 400amp service at my main panel in my home and I'll be running a 125amp service out to my 48' x 28' 1300 sqft shop in the next few weeks.

I am planning the shop wiring right now and I want plenty of room for improvements in the future. I've mapped out a number of 50 amp receptacles for welders, a plasma cutter, an air compressor, and several other tools that run on 240v. In all I am looking at 10 240v breakers in the panel.

I plan on upgrading most of my equipment over time as my compressor is a smaller one, my welder is relatively small and I would like to get a smaller mill and lathe at some point. As such I am planning on wiring the 50 amp receptacles with 6/2 wire.

Is it important that I size the breakers for the current equipment that I have or can I purchase several 50amp breakers in order to avoid having to pay for the larger breakers in the future?

Thanks

whats the HP rating on the comp motor? If more than 3HP, it needs to be hardwired. a 50a nema outlet wont work.

 

[sberry]

This is one of those things that is raved over about the code but rarely explained as to why. I would like to hear the reasoning behind it.
But to the op, I can tell you this from experience that all the worry and fuss is highly over rated. Plans change, equipment does and I have parked a lot of money over the years in the walls based on **** I thought I would do. I piped inch where 1/2 would do in some cases, some I got right too. I mis estimated a lot of utility demand for a long time especially in regards to air and electric. Water is slightly different in my case due to distance and some irrigation and tank filling and well size but those are not so much a problem for most with limited supply.
I have 400A electric, could make it easy on 200 and would be a lot easier for backup.

 

[sberry]

I really did better with my shop than I did on some other buildings with this as I didn't plan in quite so much detail and wired a lot as I went. There are still a lot of places I have 2 circuits where 1 would do. It was a lot cheaper and easier where I added as it was needed.

 

[redidbull]

With the 6/2 you will not have a neutral. That may be a problem if the tool also needs 120V. Jim

 

[Norcal]

With the 6/2 you will not have a neutral. That may be a problem if the tool also needs 120V. Jim

Everyone seems to suggest running a neutral to 240V equipment but if overcurrent protection is over 20A you cannot simply tap off for 120V, overcurrent protection will be required.

 

[sberry]

Not only that I cant think of a single time I ever needed it. Only things most face that has that are electric dryers and ranges, not sure about ovens for powder coat etc but I don't own any 120/240 shop stuff.

 

[redidbull]

Everyone seems to suggest running a neutral to 240V equipment but if overcurrent protection is over 20A you cannot simply tap off for 120V, overcurrent protection will be required.

I was thinking more along the lines that it would maybe need it for the machine he that is being hooked up. Some dryers and stoves have the 4 pin plug bringing the neutral in. Jim

 

[Norcal]

I was thinking more along the lines that it would maybe need it for the machine he that is being hooked up. Some dryers and stoves have the 4 pin plug bringing the neutral in. Jim

Dryers and ranges ALWAYS have a neutral. Some cooktops do not need one.

 

[OccupantRJ]

I wired my shop into the walls except for the welder receptacles and other 240 volt circuits which were run in conduit up and through the attic and down the surface of the walls. This let me complete the shop with the 120 wiring, then I added the 240 circuits as needed, in the wire sizes needed, in the exact locations needed, as I needed them. I have 12 machines that require 240 volt.

 

[sberry]

Good catch, I was going to add that but figured it would complicate matters.

 

[Ohmthis]

On the welder outlet(s), just put one outlet in, in a common area. Then make a extension cord that can get to anywhere in the shop. Most of the time your welding will not be close to your outlets. This is a much cheaper route than putting 5 outlets in to cover distance. Compressor wise, put in one circuit that will cover future expansion and pipe lines to other areas. I think the idea of changing and expanding gets blown out of proportion. If/when the time comes run some conduit and place the wiring then. You can think ahead by running some empty conduit into accessible areas (attics, outside, crawl spaces) and have an easier project when it’s required.

 

[Montyx5]

whats the HP rating on the comp motor? If more than 3HP, it needs to be hardwired. a 50a nema outlet wont work.

I see this mentioned a lot, could you reference the NEC code that applies to this.