piggy back a 220 outlet?

[Foras Noir]

Man I hate to do this. This is why I don't respond to people who are clearly just shooting it. In this case, you could hurt someone. I am going to respond.

If the original recpt. was installed under NFPA 70 2008 NEC art. 100 "Branch Circuit, Individual," then you will, absolutely no doubt about it, make it worse by tapping in a second recpt. If you (poster responding to me) don't know why, then stop posting on electric. If you (original poster) don't understand why, please get an electrician.

I am sickened by this thread. A guy shows up with a real life question. He gets endless BS from this board. Some of which is actually dangerous.

The real sick part is - if he just checks the NEMA classification of his setup and his neutral status he can do this safely. But you posters with no training and no actual knowledge could be leading him to a very, very bad end. If he taps a dedicated circuit (which the photo shows) under the old rules (meaning a down-sized or missing neutral) and gets it wrong - one of my coworkers could die responding to the fire.

Shame on you people and shame on the owner of this forum for allowing this insanity.

[Foras Noir]

Almost a good response. Do you know why it is not actually good? Walls.

If you botch up ext. cord setups - it is bad no doubt. If you botch up connections inside a wall - like non-compliant tapped recpt. on a dedicated pre-2008 circuit - it kills people.

It is vastly better to have a visible electrical problem than a concealed one. That is why we have "cover inspections."

I don't mean to be harsh here but - my God - the stuff posted on this thread is crazy.

It is NOT - NOT at all - better to have a concealed electrical problem.

Is there anyone in a management position on this board reading any of this? This forum is dangerous. Get a moderator. No I don't mean me. But for God's sake people, this stuff is crazy.

[Dan Friedrichs]

If the original recpt. was installed under NFPA 70 2008 NEC art. 100 "Branch Circuit, Individual," then you will, absolutely no doubt about it, make it worse by tapping in a second recpt. .

Why? The OP clearly said he was only using one outlet at a time. He is not making it more dangerous, as long as that condition is maintained.

Shame on you people and shame on the owner of this forum for allowing this insanity.

You are overreacting a little. This is simple residential wiring. I don't disagree that you are technically correct, but there are wide safety margins built into most of this stuff. Houses built to old code standards aren't out bursting in flames everyday.

[John Coloccia]

Foras:

Help me understand the situation you're talking about as I wired my shop just before all this went into effect. I'm guessing it goes something like this:

Outlet 1 is wired with 10AWG (for example) for the two hots and ground, and maybe 14AWG for a neutral (maybe to run a light or a small auxillary motor, for example).

If Outlet 2 simply taps off of that, and also requires a neutral, you can run into a situation where running both machines simultaneously could easily exceed the current carrying capacity of the neutral without ever tripping a breaker.

Also, a fault that shorts to neutral can exceed capacity without ever tripping a breaker.

And finally (and this is the biggie, I think), if the current machine is hard wired with a neutral, and the new machine needs a neutral, you can get yourself (or someone else) killed if you disconnect the first machine. This will disconnect the neutral and ground from the second machine, which is generally bad. So adding an outlet in this particular case does actually make the situation much worse in that it adds a place where you can get electrocuted which was not there before, and which is impossible to detect without detailed knowledge of how the shop is wired.

so the cases where he's okay is:

1) there's no neutral, just two conductors and a ground
2) there's a neutral that's sized the same as the current carrying conductors AND there's a receptacle for the first machine, not hard wired.

Is that true?

[Greg Portland]

The OP clearly said he was only using one outlet at a time. He is not making it more dangerous, as long as that condition is maintained.

Sorry Dan but I'm going to agree with Foras on this one. You seem to be saying that the OP will be the only person to ever live in this home and work in that shop & that everyone over the next 100 years who enters this space will know not to turn on two tools at once? I guess you'd advocate exhausting carbon monoxide into a home because as long as the person keeps a window open it will be safe.

According to some posters, since a 2nd outlet is OK you might as well run 10 more outlets on the same line (just be sure to only run 1 at a time)

[Dan Friedrichs]

Greg, the breaker should still be rated for just what the wire can carry, so if someone plugs in two devices which exceed that rating, the breaker should trip, protecting the wire. You'll notice that you have many dozens of 15 or 20A 110V outlets around your house, but you cannot safely plug in a device which draws 15A to each one of those outlets. For that matter, you can't even plug in 2 devices which each draw 15A into a duplex outlet.

[Kent A Bathurst]

Dan - I'm with you - maybe I am confused, maybe not, but I was pretty doggone sure that if you turn on more amps than the circuit can safely handle, there is this gizmo called a circuit breaker that is there for that exact reason.

Seems to me to be the same deal as if I had one receptacle for a 20a circuit, and then the future homeowner plugged in a 30a device - the breaker will do its job. If he decides to replace the 20a breaker with a jillion amp breaker but not upgrade the wire, then how is that my concern? I am positive there is no deed restriction on my property that prohibits ownership by card-carrying morons.

Greg - I clearly am not getting your point, so I apologize - are you running 4ga wire with a 60a breaker in your den + living room for your 8-receptacle baseboard 110v circuit in case the next guy uses 8 power strips with 6 outlets each, and then plugs in 48 stereo amps @ 1000 watts each?

I have 10 ga wire with a 30a breaker running ONE 240v circuit to 4 machines: jointer, planer, TS, DC. I only run 2 at a time - except that one time I ran three.........except I didn't run 3, I ran zero. And - the jointer, TS, and planer all have mag switches, so when you reset the breaker, none of the "ouchy-call-911-you-are-ER-bound" tools fire back up.

[Dan Friedrichs]

John, I know you asked Foras, not me, but just to clarify:

If Outlet 2 simply taps off of that, and also requires a neutral, you can run into a situation where running both machines simultaneously could easily exceed the current carrying capacity of the neutral without ever tripping a breaker.

Yes, but the OP's machines are motors, hence no neutral current. It seems unlikely that a future owner of the home would have two 220V appliances, both of which had 110V circuits as well, and the new homeowner wished to run both appliances simultaneously in the garage. Nonetheless, I'd probably verify the size of the neutral conductor if the OP's receptacles have a neutral connection.

And finally (and this is the biggie, I think), if the current machine is hard wired with a neutral, and the new machine needs a neutral, you can get yourself (or someone else) killed if you disconnect the first machine.

The OP said the current machine is NOT hard-wired.

I'm not sure I understand this one, though. You're suggesting the first machine could be hard-wired in, and someone could open the junction box which connects the supply, machine #1, and outlet for machine #2, and in an attempt to remove just the connection for machine #1, somehow remove the neutral and/or ground for the outlet for machine #2? I don't see how that is likely. What prevents them from disconnecting the hots, as well?

[John Coloccia]

re: breakers
Only the hots are on breakers, not the neutrals. If you have a 14AWG neutral on a 30A circuit, you can easily fry up the neutral, hence it's now required to be the same size as I understand it.

re: motors and neutrals
My dust collector is wired with a neutral to get 120 to my remote control. I almost wired my bandsaw with a neutral to run a light (wish I had). Even though my whole shop is wired with 10AWG, I still protected that neutral with a 15A switchable fuse (installed locally at my DC's relay box). This protects the wiring in the remote. Technically I don't think I had to, but the remote is not designed to see 30A so I thought it was a good precaution.

re: everything else
I've got no dog in this fight. Just trying to learn. My personal opinion is wiring to code is generally a good thing. I believe that others have probably thought through this more than I have. All my neighbors are a good distance away from me, so I probably don't care if anyone else has safe wiring or not, but if anyone asks I'd always recommend following the local building code (which usually follows NEC).

[Curt Harms]

wouldn't the simple and correct answer be (assuming the O.P lives in a zoned area):

However the AHJ (authority having jurisdiction, i.e. building inspect) wants it done? There are some local kinks not addressed by national codes out there. Local codes supercede national codes, I think.

[Kent A Bathurst]

re: breakers
Only the hots are on breakers, not the neutrals. If you have a 14AWG neutral on a 30A circuit, you can easily fry up the neutral, hence it's now required to be the same size as I understand it.

a-HA!! - a plain-spoken explanation of the root issue. NOW I get it - Thanks John. Still seems the easy out is to put a duplex into the box that holds a single.

In my case, I ran 3+1 10 ga on the 4-machine circuit, and used dual-voltage duplexes for misc, transitory use, except for the DC remote. No issue in 6+ yrs.

[Tom Veatch]

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).

Nothing about this question implies anything other than a single phase 240v branch circuit which is usually wired with 3 wires - 2 hots and a ground, no neutral (at least in my jurisdiction) and with NEMA 6-XX outlets (which has no terminal connection for a neutral wire). So where did all this neutral wire red-herring, issue-clouding stuff come from?

Recast the question: Can an additional outlet be added to a 120v branch circuit? How about a 240v branch circuit? I know of nothing that restricts either a 120v or a 240v branch circuit to a single outlet.

[Greg Portland]

if you turn on more amps than the circuit can safely handle, there is this gizmo called a circuit breaker that is there for that exact reason

Only the hots are on breakers, not the neutrals.

John beat me to it, that is the root of the issue here... some people are talking about hot wires, some are talking about neutrals.

My main issue is people saying to ignore the electrical code. Parts are cheap, do it the right way.

[Dan Friedrichs]

My main issue is people saying to ignore the electrical code. Parts are cheap, do it the right way.

Agreed. I don't think anyone here suggested ignoring code. It's perfectly code-compliant to add a second outlet to this branch circuit.

Nothing about this question implies anything other than a single phase 240v branch circuit which is usually wired with 3 wires - 2 hots and a ground, no neutral (at least in my jurisdiction) and with NEMA 6-XX outlets (which has no terminal connection for a neutral wire). So where did all this neutral wire red-herring, issue-clouding stuff come from?

Foras brought it up - I'm not sure why.

[Jerome Hanby]

From looking at the tech support forum, I guess Foras took his ball and went home...