I have a 220 outlet for my tablesaw with 10 gage wire. My questions is can I add a second outlet to the existing one so I don't have to keep unpluging machines (I would only oue one at a time).
[OP]
Member
I have a 220 outlet for my tablesaw with 10 gage wire. My questions is can I add a second outlet to the existing one so I don't have to keep unpluging machines (I would only oue one at a time).
Member
Sure, but we need more details on how you want to do it. I think you would need to add another outlet box. Is that your plan?
Member
What is the current draw for the two machines?
Are they both running on 220V?
What is the breaker rated at 20A, 30A?
Contributor
Yes.
1010101010
When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.
Member
You can add another outlet to a 220 line, same as a 110v line.
When I built out my shop, I ran two 30 amp circuits for 220v machines. I have 5 outlets per circuit around the shop, clearly marked on each outlet for each circuit. I can plug into any of the outlets, but make sure that you aren't running two machines on one circuit over the amp load. Rule of thumb, take 75% of the breaker amperage and that is your max load on that circuit.
(ex. 75% of a 30 amp breaker is 22.5 amps max load.)
Contributor
I just had my electrician come in and do just that. He jumped off a plug that will be running a piece of machinery. I had told him that I would only be running one machine at a time, along with my DC. He made sure to tap into a box that was dedicated to one piece of machinery. The DC I had him wire into another circuit and run a dedicated line to the DC.
Contributor
I did what Michael said. In addition, I ran dedicated circuits for machines that will/can be on at the same time, table saw, dust collector, compressor, air conditioner. All of them have the potential of being on at the same time. Everything inspected by the city inspector.
Sam
[OP]
Member
I have a 30A breaker and I would be switching from my TS and Jointer, both are 20A pulls. I want to add another outlet just to the side of the existing one. Thanks for the ideas.
Guest
Yes is not the right answer.
Do you have a neutral pulled to the existing outlet? Do you need a 2P3W (for example an L6-30R or 6-30R receptacle) or a 3P4W (for example an L14-30R or 14-30R receptacle) outlet for the proposed plug?
First, find out what type of NEMA plug you need. Either by reading it on the actual plug or manual. If that fails, look up NEMA plug sets on the net. But, absolutely, you need to know if the new one is 2P3W or 3P4W.
Second, once you know if you need a neutral (3P4W), then find out if you have one. If you do, make sure it is the same AWG as the to current carrying, non-grounded conductors. I say that because there are situations where the neutral is only present to pick up the unballanced portion of the load and, in the past, it was allowable to use a down-rated conductor for that purpose.
If you don't understand all of what I wrote, get help. If you do, and the neutral situation is OK, go for it. Otherwise, get help. Electricians actually do matter.
Last edited by Foras Noir; 04-30-2010 at 2:57 PM.
Contributor
Foras,
I think the OP currently plugs either one of two machines into that existing outlet. Assuming the existing outlet is wired correctly, there is nothing wrong with adding a second, identical, outlet in parallel with the existing one.
You are right in general, but for this specific situation, an unconditional "yes" is, in fact, the correct answer.
Guest
Nope. Go back to your code book.
If the orginal installation does not meet current requirements, then additional outlets will constitute "new work." If his current carrying grounded conductor (you know - that white wire) was not correctly installed by our NFPA 70 2008, he needs to fix it. It will depend - as I said - on which NEMA classification his plug set fits and how the grounded conductor was installed. For you code-heads who want to scare yourselves, read the "tapping" and "grouping" rules (210.4 (D) is the ugly one). Does his install meet that crazy rule? If it was built before NFPA 70 2008 it doesn't.
Come on you guys, if you don't have a license, don't give unqualified answers. If you do have a license and you are doing that, get a new job. When some asks for help - help them. Talk them through the process. Teach them what to look for, where to find information and, most importantly, when to get help.
I have responded to countless residential fires. With the exception of smoking, bad electric work is the primary cause based on my experiences. There is a reason that the National Electric Code is issued by the National Fire Protection authorities globally. It is the same reason that your local Fire Marshall has superior administrative authority over your building codes organisation. It costs $150 per year to join the NFPA. You get your money's worth. Go join and learn how to really help people.
Last edited by Foras Noir; 04-30-2010 at 7:07 PM.
Contributor
To quote Steve Martin in his early days: "Well, excuuuuuuse me!!"
When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.
Contributor
If the original installation does not meet current requirements, the OP is not making the situation any more dangerous by adding a second outlet.Originally Posted by Foras Noir
Technically, you're right, but from a practical perspective, he is running 220V motors on these outlets, so there's no current on that wire.
You make it sound like residential wiring is rocket science. Not that it doesn't have its fine details, but the vast majority of residential electricians in this country wouldn't know what a code book looks like, yet still seem to be capable of safe work.
Sure. But I'm personally more worried about plug-and-pray connections made to outlets, extension cords used in walls, and DIY'ers who can barely run a screwdriver. The OP wanted a simple answer to a specific question - not to become a full-fledged electrician. He got his answer, so moving on....
Contributor
my suggestion when you do this is to move the single box to the new position and put in a double box with a single plug in the original position. the double box will make it easier to work with the extra 10 G wires.
Contributor
Bingo.
I was starting to worry that I needed to rewire the entire house, since it doesn't meet today's code. When we moved in, I removed a half-dozen ungrounded duplex's and their wire, and put in new grounded stuff. I'm fairly confident this didn't go backwards on safety.
Christopher - Can you replace the single receptacle with a duplex into the existing box? That'd be very simple, especially since you'd avoid the fun of wrestling with 10ga wires.
When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.
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