Single 240V run, two outlets - pointers?

[Air_Cooled_Nut]

Well, aside from "don't do it"

I already have a one 240V run for my air-compressor using two 20A breakers. My box has two spaces left which I would like to use as another 240V, 20A circuit (100A box). I would like to have a single run up the wall, across the ceiling, then split into a T, where one run would go to one wall and the other run would go to the opposite wall. Thus both outlets would share one breaker (well, two 20A breakers, technically).

Obviously I am not an electrician but do try to do due diligence in researching what I'm doing plus I'm really good as a DIYer. So, my home shop is used by me only. I have nothing else (so far) that would require 240V but hope to get a 240V lift for the one side of the shop. If I should ever get a more powerful welder or whatever that requires 240V I would like the option to use it on either side of the shop. Naturally, only one of the two outlets would be in use at a time.

1. So, am I committing a cardinal sin by wanting to do this? Or is it okay? Or okay but just not recommended?

2. Also, is there some kind of indicator available that lets one know if a circuit is in use? Like a red light would come on if electricity was flowing in a circuit? That, at the least, would provide a warning.

 

[Steevo]

It is possible, and is sometimes done.
It may not be code-compliant.
The drawbacks are that you know only one receptacle can be live at a time, but a future owner will not know that. This could result in problems for him/her.

You also want to find a welder that is close in maximum amperage draw to your compressor, so that you can size the wiring and breaker properly for both.

To do what you are asking about, you will need a junction box at the junction/splice location (mid ceiling as you described it). You then run your correctly sized wire from breakers to J-box, from each receptacle to the J-box, and wire nut them together in the J-box with the correct size wire nuts.

 

[Burtonrider10022]

What about flipping a switch when you want to use 1 or the other? Like an inter-lock kit type of set up where when the welder is on, you have to turn off the breaker to it before you can turn on the breaker for the compressor.

That should alleviate the future homeowner from going full retard as well.

 

[GShelton]

I would just do a sub panel. It could be a small 60 amp unit. Feed the sub pane from the main panel (4 wire) and then run 1 separate feed to each plug. Hope this makes sense.

 

[Aceman]

How big is your panel, how many spaces does it have?

 

[theoldwizard1]

I would just do a sub panel. It could be a small 60 amp unit. Feed the sub pane from the main panel (4 wire) and then run 1 separate feed to each plug. Hope this makes sense.

Good solution, but the feed to the sub panel would have to be upgraded as well as the breaker in the main panel box.

I don't think mounting the sub panel at the proposed junction (on the ceiling) would pass an inspection !

 

[theoldwizard1]

What about flipping a switch when you want to use 1 or the other?

Leviton 1286 - DPDT 20A (1hp). Switches the hots only. About $60
Leviton 1288 - DPDT 30A (2hp). Switches the hots only. About $75

If you mounted it at the proposed junction (on the ceiling) to minimize wire length, you would need a long stick or a ladder.

 

[Air_Cooled_Nut]

Here's my box:
https://sphotos-a.**.fbcdn.net/hphotos-prn1/603964_480528141969927_618094452_n.jpg

I already have the air-compressor on it's own 240. See the empty spot and the one above it (red and black wires). That's where the next 240V will go. The red and black wires are getting pulled, they were a circuit I don't need.

A switch 'tween the two circuits would be fine w/me.

 

[Charles (in GA)]

What you are describing is a simple 240v branch circuit with multiple outlets on it. If you had too much stuff plugged in, and overloaded it, same thing would happen that would happen to any other circuit, it would trip the breaker. Big deal.

You restrictions on use would be the same as any other branch circuit, no single plug and cord connected load is allowed to exceed 80% of the circuits capacity, which is the same restriction that is found on any household branch circuit.

That being said, you do not say, and your shop thread really doesn't tell us, if the shop is DETACHED or ATTACHED to the house (could make a difference if certain Dwelling rules apply or not) and...........

Why don't you just bite the bullet and do the right thing and install a larger panel? Panels are not that expensive in the big scheme of things. I'm really at a loss to understand why people under estimate the size/breaker capacity of panels they need or could use in a shop.

If this panel is supplied from a feed in your house's main panel, the size of your main breaker does not matter in this panel as it is only acting as a disconnect, go buy a full 40 space panel with a main breaker and install it, then you have all the room in the world to do the wiring job "right".

Charles

 

[ishiboo]

What you are describing is a simple 240v branch circuit with multiple outlets on it. If you had too much stuff plugged in, and overloaded it, same thing would happen that would happen to any other circuit, it would trip the breaker. Big deal.

You restrictions on use would be the same as any other branch circuit, no single plug and cord connected load is allowed to exceed 80% of the circuits capacity, which is the same restriction that is found on any household branch circuit.

+1.

Why don't you just bite the bullet and do the right thing and install a larger panel? Panels are not that expensive in the big scheme of things. I'm really at a loss to understand why people under estimate the size/breaker capacity of panels they need or could use in a shop.

If this panel is supplied from a feed in your house's main panel, the size of your main breaker does not matter in this panel as it is only acting as a disconnect, go buy a full 40 space panel with a main breaker and install it, then you have all the room in the world to do the wiring job "right".

Charles

-1. He wants to have two outlets on one circuit and you're recommending a new panel? If he does not need the load capacity and it is just for convenience, why?

Looks like open studs, if this was planning-for-the-future-before-drywalling I would suggest two separate 10-3 runs or conduit, but still leaving the panel until necessary to change it out.

 

[Air_Cooled_Nut]

The shop is detached from the house by 50' or so and the feed comes from the house (hmm, I'm pretty sure it does). What you see is what the PO had done so it's what I'm working with. The shop is for hobby use, not actual business. Yes, I know that over-loading the circuit would cause the breaker to trip. If I had paid for the installation I would've built it accordingly

I'm going to plywood the lower 1/3 of the walls with sheet rock for the rest of the space.

 

[Air_Cooled_Nut]

...
Looks like open studs, if this was planning-for-the-future-before-drywalling I would suggest two separate 10-3 runs or conduit, but still leaving the panel until necessary to change it out.

Okay, confusion here. The existing 240V is in conduit. The rest of the circuits are not except for part of one, which is a couple of the florescent lights. Does a 240V require conduit? So one run using conduit or two runs without conduit? Looking at my current 240V breaker pair I see that each breaker can accept two individual wires.

I'm not sure if everything is currently to code The PO's brother had some contractor experience and did some of the work...without permits...

 

[Charles (in GA)]

The panel is virtually full, look at his web site. The shop is relatively large, and has a lot of potential. He will get the walls finished, closed up, and suddenly want a dozen more receptacles, places to plug in grinders, workbench lights, a parts washer, and a host of other things....... that is why I suggest a larger panel that will have the capacity to do everything he wants, now and into the future.

The OP needs to come up with a through wiring plan for the future and implement it now, before he closes the walls.

Why leave a panel that is clearly crowded and sheetrock up around it THEN have to replace it. The wall above the panel needs to be closed with a removable panel, will make future work much easier. There is no where to go but up as this is between the garage door and the man door. I did the same thing.

Thats a Square D Homeline panel. The two breakers on the lower left are regular 1" wide breakers. The bottom left one has two wires on it (legal on that breaker) and the next one up has nothing on it.

Bottom RH double pole has a white wire on it that has not been remarked to red or black, which is a no-no.

Charles

 

[Air_Cooled_Nut]

Gotcha Charles, thanks. The white wire mis-color is my fault...I shall correct. Funny, but I did color it at the receptacle

And correct, up is the only direction.

 

[Charles (in GA)]

Okay, confusion here. The existing 240V is in conduit. The rest of the circuits are not except for part of one, which is a couple of the florescent lights. Does a 240V require conduit? So one run using conduit or two runs without conduit? Looking at my current 240V breaker pair I see that each breaker can accept two individual wires.

I'm not sure if everything is currently to code The PO's brother had some contractor experience and did some of the work...without permits...

No conduit needed if you put it in the walls and sheet rock it over like the rest. If all you want is 20 amp use the yellow 12 gauge romex and recolor the white end to red. You don't need a neutral for 240v

I cannot tell what the existing 240v does. It leaves the breaker, turns down and runs across the bottom of the breakers, makes a 180 and lays on the bottom of the panel, travels to the right and then turns up and runs to the top where it appears to be wirenutted, thats where I lose it.

Its a little hodge podge but I've seen alot worse. It (to me) just isn't big enough for a shop of that size, even if you are not doing anything but polishing cars in it.

The 240v breaker is known as a DOUBLE POLE and while it really is two breakers, they are permanently and inseparably joined by the rivets that hold them together. It is ONE double pole breaker,, but it takes up two spaces.

Look closely at the bottom RH breaker, it only accepts the two wires that are connected. Square D made the double poles so that you cannot put two wires on each terminal like the single poles, they bent up a tab or ear to block the channel where the extra wire would go. I just looked at one the other day in Home Depot.

Charles

 

[Air_Cooled_Nut]

No conduit needed if you put it in the walls and sheet rock it over like the rest. If all you want is 20 amp use the yellow 12 gauge romex and recolor the white end to red. You don't need a neutral for 240v

Okay.

I cannot tell what the existing 240v does. It leaves the breaker, turns down and runs across the bottom of the breakers, makes a 180 and lays on the bottom of the panel, travels to the right and then turns up and runs to the top where it appears to be wirenutted, thats where I lose it.

Almost. The wires do the 180 at the bottom then go straight up into the right conduit. The wire nutted wires were meant to go into a 240v breaker; they are nutted to protect them and they travel down and to the left of the box then up into the left conduit. The PO had them marked for a water heater but there's nothing, just a wire run.

Its a little hodge podge but I've seen alot worse. It (to me) just isn't big enough for a shop of that size, even if you are not doing anything but polishing cars in it.

With what I have to deal with in the house, hodge podge doesn't surprise me.

The 240v breaker is known as a DOUBLE POLE and while it really is two breakers, they are permanently and inseparably joined by the rivets that hold them together. It is ONE double pole breaker,, but it takes up two spaces.

Gotcha. Thanks for the definition.

Look closely at the bottom RH breaker, it only accepts the two wires that are connected. Square D made the double poles so that you cannot put two wires on each terminal like the single poles, they bent up a tab or ear to block the channel where the extra wire would go. I just looked at one the other day in Home Depot.

Charles

I just checked that double pole breaker and it DEFINITELY can accept two wires per [individual] breaker. Did I mess up? I got them from Home Depot, too.

 

[Charles (in GA)]

I just checked that double pole breaker and it DEFINITELY can accept two wires per [individual] breaker. Did I mess up? I got them from Home Depot, too.

I'll look tomorrow when I'm at HD. I just looked the other day, those breakers should not accept two wires per terminal. Possibly Square D has changed the configuration of them. I'll take some pics.

The placard (tiny) on the breaker will tell you how many wires and what gauges are allowed to be installed on it.

Romex is supposed to be protected. If you encase it in walls, its acceptable, if left open (permanently) it is not OK. There is lots of exposed Romex in the world, I have some, just about everyone does.

Charles

 

[ishiboo]

The 15-30A double poles have the same tabs as the singles, thus are rated for two wires. Not sure about the 40, of course the higher amperages use a single screw with a little wedge and are only good for a single wire.

 

[Charles (in GA)]

The 15-30A double poles have the same tabs as the singles, thus are rated for two wires. Not sure about the 40, of course the higher amperages use a single screw with a little wedge and are only good for a single wire.

I just stopped at HD today. You are correct, up to and including the 35 amp had the double terminals, the 40 and up jumps to a more "normal" single screw and wire clamp set up. It may have been a GFI breaker that I saw the double wire tab with one side blocked off.

Charles