Combining two 15amp circuits to a 30amp

Shawn Philip Nelson

Shawn Philip Nelson

Veteran
Okay, so I know the risks. I'll have an electrician help me with this. I also know you have to make sure you're not grabbing two of the wrong legs of electricity.

That said, has anyone made a box such that two power cords are feeding it, from different 15amp plugins, then combined they output 30amps? This would enable running a 2.5kw HMI off of household power. You could also run a 2k without problem, even if there were other things on the circuits (provided each circuit still had about 9amps to give you).
 
I think you can do it, because some AC's/washing machines and heaters split the amp loads on the double breaker slots. Make sure you get the double breaker, so they both trip if one for some reason gets overloaded. And of course you'll need cable rated for 30amp
 
Hi Shawn:

This is called a tie in and is extremely dangerous. Unless you have a licensed electrician actually doing the work for you, you are risking frying yourself.

Not worth it. Even union gaffers aren't thrilled to do these. Better to rent a genny.

Dan
 
puredrifting said:
Hi Shawn:

This is called a tie in and is extremely dangerous. Unless you have a licensed electrician actually doing the work for you, you are risking frying yourself.

Not worth it. Even union gaffers aren't thrilled to do these. Better to rent a genny.

Dan
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I know what a tie-in is, to break open the panel box and add new circuits or tie-in to a larger box. That is not what I want to do. I want a box that takes in two cords (each running from different wall plugins located on different circuits) and would feed out one bates. It's to give me 30amps *without* a tie-in. So shortcutting the danger of tapping circuit boxes.
 
What you're talking about is not simple or practical. Remeber Amperage is the flow of electricitiy and it takes the path of least resistance. So to pull 30 amps from two 15 amp circuits would mean you'd have two exactly balanced circuits, nearly impossible. The only solution is go where you have the 30 amps of potential and take your pick off from there, ie a tie in or a generator. I would not try anything else.
 
I'm with Gopher I don't think this makes electrical sense. If it did everybody and his brother would be carrying these boxes around.

If you have to ask this question on a forum like this - DON'T TRY IT AT HOME!

But that said, Maybe I'm worng. look into how those washing machines are set-up. I've been doing this many years and used to do Tie-ins all the time and I've never seen anyone do this.
 
I use a 4k mole zip light that has two 20amp cords. There is one available on ebay or maybe Visualproducts.com. Same thing..However Shaneous, this powers up two different circuits. I know exactly what you mean and want, and I too wish this could happen at every location and with every light over a 1.2 k- to 18k....Get a Bates to edison adapter and rent a genny....
 
In theory, it should work. Think about it for a moment: Two circuits in parallel will keep the voltage the same but double the amperage. Therefore, if a box was built that paralleled two circuits, the output should be 115V 30A - in theory. This is exactly how it would work if you had two batteries in parallel. I know, because on my sailboat, I have four 8D batteries paralleled. The voltage is always 12v, but the amperage (or amp hours) is now up to 1000ah - each battery is rated for 250aH.

What I don't know is if this applies to AC as neatly as it does to DC.
 
Your sailboat battery example works because your batteries even out once you wire them together, their charge levels equalizes between them, and they become one big happy battery. You power your boat with one thick (+) cable coming from the battery bank. With AC, as Gopher_Greene correctly explained, if there are 2 long wires coming from 2 circuit breakers, one of them can end up carrying most of the current (30A), causing the breaker to trip.
 
Hmm, shall we place bets on the outcome? I'd be concerned about safety issue as well as ground loops causing interference. This could be exciting - be sure to take some pix of "exhibit 1".

Seriously, I was constrained I would connect a home-made cable from the lights to a heavy duty (30 amp) plug in the laundry room, etc.

Good luck, Michael
 
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If anyone tries this, you will need to be very careful since you never know if when the electrician (or whoever) installed each of the outlets wired the hots to the same side of the plug. If they are reversed on the 2 outlets when you plug it in to the second outlet you could really get knocked on your ass.

Another option, especially if you are shooting in lots of houses or other places with dryers or oven plugs is to make a box that is 240v in with a standard dryer plug and has a 30amp out via edi or a 60amp bates.


You would still want an electrician to make that for you.
 
The dryer method seems like the best solution without going to a generator. I remember way back in my highschool days they used to have a dryer type plug in our gym for dances and such. It went to a simple breakout box.

You could easily run two 2.5K HMI's since you have two isolated 30 AMP circuits. I believe you can do the same with a electric oven plug as well, however, I believe they are slightly differently shaped-- not sure about the amperage.
 
Lenilenapi said:
The ziplight circuits are each powering separate bulbs. Its a completely different situation.
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Did I not make that clear in my post ? The two seperate circuits.... I do realize it's not the same thing. I was just sympathizing with his dilemma, I too wish lights of the size he was referring too could be plugged into several edison outlets rather then a genny as an option.
 
I'm going a different route. I'll be working with an EE/Electrician to make me a cable that takes one 240v/30amp dryer socket and converts it to two 120v 30amp sockets. So I can run two 2k's or 1 2.5k and 1 2k.

This path is much more safe.
 
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