Is a 50A 6/2 NM OK for sub-panel feeder?

[Kevin Stricker]

Hello Creekers, this is my first post on this site though I have been lurking for a while. I am in the process of converting my 2 car garage into a workshop. Fortunately for me it has never really been a garage, more of a storage area while I have been remodeling my home, so I don't have to share it with any cars :).

When I purchased my house three years ago my electrical was a mess. Double lugged CB's everywhere in my 200A Stablock panel, hidden junction boxes in the joists, and even some 220 baseboard heaters run on 14ga wire. Needless to say after spending a few grand replacing the main panel and adding a 100A subpanel in my utility room, re-running the wire for most of my kitchen, all of my baseboard heaters, and most of my basement I have learned a few things about electrical.

The question I have is in regards to running another sub-panel to my garage to handle the shop tools and to allow me to lock out the shop power to keep my son from getting into trouble. It seems to me that I have a few choices available:

1- Run a new line from the main panel to the garage for new sub-panel. I cannot afford to run another big feed to the garage( which is on the opposite side of the house from both the main and sub panels)but I did run a 2.25" conduit during the remodel so I can do this in the future. If this is my only option I will continue using extension cords off the current outlets in the garage until I can afford the wire.

2- Use the old range circuit(50A CB) for a new sub-panel and run everything from this. It is a 6/2 aluminum NM wire, which was freed up when I moved the range and had to run a new line as the old one did not reach. My concern here is that it does not have a dedicated neutral, which I thought was now code for 50A circuits. Maybe I could just de-rate it and only use a 30A CB in the main panel?

3- I moved my washer and dryer to the util room so I have a dedicated 20A circuit(washer) and 30A circuit(dryer) available in the wall shared with the garage. I thought I could use the old drier circuit to a sub-panel in the garage for outlets only. Use the old washer circuit for additional lighting. There is another circuit feeding the lights that are currently in the shop but nowhere near enough light currently.

The garage is finished, so I plan to surface mount everything. I currently only have a compressor and tablesaw that can run on 220 ( currently 110), all other tools are hand tools. Want to be able to add a DC system and a planer/joiner combo unit when funds allow. Most of my woodworking is doing trimwork and built-ins, but plan to focus more on cabinetmaking in the future. I try to always do things the "right way" the first time, but am really on a tight budget right now.

Thanks for enduring my long post, and for any advice you can give.

[Sonny Edmonds]

Hi Kevin, Welcome!
While many would say you need more, I run off of a 50 amp feed to my shop. Just an 8 position sub panel.
Maybe you would like to take a look at my sub panel advice (http://home.earthlink.net/~pie/subpanel.htm)I wrote up about another Kevin.
Personally, I think surface mounting is the way to go. That way the power system can, if ever need be, moved with the shop and used in part or all at a new location.
You could get the best of both worlds by bringing a neutral in for your new panel, or a ground and use the existing ground as the neutral. Just have to make sure you mark it as a neutral with white electrical tape where ever it is accessible.
A dedicated ground needn't be in a bundle, conduit, or cable. Just well defined as a ground.
Lots of ways to skin a cat. ;)

[Chris Friesen]

For the subpanel, you need to somehow provide two hots, a neutral, and a ground. The neutral is so that you can provide 120V as well as 240V.

You don't specify whether the garage is attached or not. If it isn't, I think you may have the option of using the old range circuit and adding a ground rod to provide the ground for the new subpanel.

If the garage is attached, then I don't think the ground rod is an option. You'd need a proper three conductor (plus ground) cable so that both the neutral and ground are carried back to the main panel. The existing range circuit could still be used (with the appropriate precautions for aluminum conductors) but not for a subpanel--it would only be able to provide a 120V _or_ 240V circuit, but not both.

[Rollie Meyers]

"2- Use the old range circuit(50A CB) for a new sub-panel and run everything from this. It is a 6/2 aluminum NM wire, which was freed up when I moved the range and had to run a new line as the old one did not reach. My concern here is that it does not have a dedicated neutral, which I thought was now code for 50A circuits. Maybe I could just de-rate it and only use a 30A CB in the main panel?"

What you have is SE cable, prior to the adoption of the 1996 NEC it was allowed to use it for a 120/240V 3 wire feed for a electric range, do it right & run a new feed for a subpanel since the neutral & equipment grounding conductors must be separate after the service equipment (main service). If your in a area that has adopted the 2008 NEC code SE/SER cable has to be treated like NM cable & sized per the 60°C column for allowed ampacity.

[Rob Russell]

You could get the best of both worlds by bringing a neutral in for your new panel, or a ground and use the existing ground as the neutral. Just have to make sure you mark it as a neutral with white electrical tape where ever it is accessible.
A dedicated ground needn't be in a bundle, conduit, or cable. Just well defined as a ground.
Lots of ways to skin a cat. ;)

Sonny,

What you propose violates the NEC.

All conductors for a circuit must be in the same raceway or cable. There are some allowable exceptions if you want to add an Equipment Grounding Conductor to a circuit that doesn't have one.

The Neutral must be an insulated conductor. 6-2 SE only has 2 insulated conductors - you can't use the sheathing wrap as the neutral.


So:

You can't add a Neutral by pulling a separate conductor because the Neutral has to be part of the cable.
You can't use the grounding wrap in the SE as a Neutral because it's not an insulated conductor.
It is true that - if Kevin had a cable with 3 insulated conductors - he could pull a separate conductor and use that as his Equipment Grounding Conductor, although there are conditions that need to be met when you do this.



As an afterthought, Kevin could use the 6-2 SE and put in a 40A or 50A 120v subpanel depending on whether you have to adhere to the 2008 NEC. That would at least allow you to have the ability to put in more 120v lighting and utility receptacles. Use the 30A dryer circuit for your 240v machines until you can pull the appropriate conductors through your 2.25" conduit and put in the 240v subpanel that you want.





Rob

[Kevin Stricker]

Thanks for the replies guys. Sonny it was your post on the other Kevin's post that lead to me posting this. I am guessing maybe it is an older article, when using a 2 wire conductor was acceptable for subpanels?

So what if I was to run a subpanel just for 220, then would it be OK to use a 6/2 feed for a subpanel?

I already have one 20A dedicated circuit for the garage, and the garage lights and door opener are on a 15A circuit shared with a few other lights. I can just run my lights and 110 outlets off those two circuits and/or use the old washer circuit as well. I could also just tap into the 10/2 old dryer wire and run my 220 with more 10/2.

What that doesn't do for me is allow me to lock out the outlets in the garage for safety. Is there any kind of switch I could use for this?

Thanks again for the replies.....

[Kevin Stricker]

Another thought was to take the 50A circuit and run the 220 off it and take the 20A washer circuit and run the 110 off of it. Would I need two seperate panels to do this? If so then it might be more expensive than a new 4/3 run.......just a thought...anyone know an answer?

[Sonny Edmonds]

Yep, it is older.
But come to think about it, so am I. :D

Here's a common lock. (http://www.cuffs4cops.com/) Ought to fix one problem.

Most panels have provision to snap a simple padlock on them. Shut off the CB's, lock it closed.
Here is another type (http://www.discountsafetygear.com/electric-cord-lockout.html?productid=electric-cord-lockout&channelid=FROOG) that secures the plug end of a cord.

And finally, one or two applications here (http://www.zymetrical.com/product.asp?3=1153&dc=3kensh-2iQ&gclid=CPnyq9CUkpgCFSEfDQod0xT5mQ) could help cure a lot of problems. :D

Use the 50 amp for your 240 volt sub panel. And the other available circuit for your 120 volt use.

[Kevin Stricker]

Thanks for the links and all the help, I appreciate it. I will check those out and see what makes the most sense..

Hahah....those ought to work great! I wonder if I can get my wife interested in any of that.......probably not.

Seriously though, I have a large locking "kill switch" for my well pump, guess I will have to start there.....

[Sonny Edmonds]

Go rent a movie called "Misery (http://www.youtube.com/watch?v=qkzPpaHqM9s)".
After you watch that you won't be thinking any funny stuff about your wife.
I gar-on-teee :eek: ;)

[Kevin Stricker]

Great movie....I cannot see that actress's face without thinking of when she started chopping....wasn't it a foot after he tried to run away?

Now you have ruined my fantasy completely......

[Rob Russell]

Another thought was to take the 50A circuit and run the 220 off it and take the 20A washer circuit and run the 110 off of it. Would I need two seperate panels to do this? If so then it might be more expensive than a new 4/3 run.......just a thought...anyone know an answer?

You could do what you propose. I wouldn't bother with a panelboard for the 20A circuit fed by the washer. It's only 20 amps, so put in a good sized junction box and just make your connections in there. You could use one of the big 4 11/16" square by 2 1/8" deep boxes commonly available at the big box stores. That would give you room for plenty of connections, as in up to (8) 12/2 NM cables if secured with external cable clamps.

You might consider putting the panelboard for the 50A/240v circuit in the location that's fed by the conduit and actually connect it to the conduit. Put in a panelboard that's large enough for your long term use. That way, when you do run the conductors through the conduit, you can just feed that existing panelboard and drop the 50A feed.

If you really want to save some long-term rework, put the junction box that the 20A washer circuit will feed right next to the panelboard and connect the 2 with a nipple. That way, when you do finally pull those conductors and fully power the panelboard, you could put in a 20A/120v breaker and feed power to the junction box. You'd obviously drop the washer circuit feed to the junction box. This way you'd have everything in the shop running through the main panelboard without having to a lot of other circuit relocation work.

[Sonny Edmonds]

Reality is a harsh mistress...
Just didn't want you to go to far down a dark path. :D

[Kevin Stricker]

Thanks for the reply Rob, that sounds like a pretty good idea. I guess I will have to price out the options and see if I should just wait and run the new wire vs having to rework later.

Thanks again everyone for your help.

[Rob Russell]

I think that you can accomplish what you want to do with little rework and excess $$$ spend.

The extra cost of my proposal is basically the extra cabling and boxes to run from the existing 50A and 20A washer circuits over to wherever the conduit feeds into your shop.

[Kevin Stricker]

I think that I am going to pull the washer and drier feeds into a junction box ( current wire length will not get them to the conduit run) then run both to the sub-panel located at the conduit like you suggested. I will use the drier feed to power two 220 circuits in the panel and junction the washer feed to the outlets in the sub-panel( so I can wire them easily to the subpanel when I can afford the wire upgrade).

Thanks again for the great ideas.....