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Author Topic: Stage Stringers  (Read 2675 times)

Chris Delcambre

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Stage Stringers
« on: June 06, 2014, 03:38:47 pm »

I am making some 20A 2 circuit stage stringers with 12-4 cable and L14-20 connectors. I am wanting to know if I can make a L14-20 to 2 Edison plugs in case I am in a location where I can't tie in power or don't have an L14-20 outlet... That way I can still use the stringers as 2 circuits but with 2 wall circuits instead of the L14-20...

Thanks
Chris
« Last Edit: June 06, 2014, 03:46:35 pm by Chris Delcambre »
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TJ (Tom) Cornish

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Re: Stage Stringers
« Reply #1 on: June 06, 2014, 03:45:16 pm »

I am making some 20A 2 circuit stage stringers with 12-4 cable and L14-20 connectors. I am wanting to know if I can make a L14-20 to 2 Edison plugs in case I am in a location where I can't tie in power or don't have an L14-30 outlet...

Thanks
Chris
If you mean using 2 5-15P to an L14-20R, no.  There are thee issues (apart from the fact that it is illegal): 

- If a device is on, there is some impedance between the hot of circuit A to the hot of circuit B, which means that if you plug in plug A but B has not been plugged in yet, you have put voltage on the exposed male contacts of plug B.

- If there is a wiring error in one of the receptacles you are using - a H->N reversal, you could short a hot to neutral, or if both were backwards, short a hot to hot.

- It is not trivial to ensure that the two receptacles you are using are on opposite phases, meaning that you could potentially be asking for 40A of return current on your one neutral wire.

This is an interesting idea, but not good unless you're sure you always have a distro.  BTW, you are using common-trip breakers for this in your distro, right?  :)
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TJ (Tom) Cornish

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Re: Stage Stringers
« Reply #2 on: June 06, 2014, 03:48:19 pm »

I am making some 20A 2 circuit stage stringers with 12-4 cable and L14-20 connectors. I am wanting to know if I can make a L14-20 to 2 Edison plugs in case I am in a location where I can't tie in power or don't have an L14-30 outlet...

Thanks
Chris
Also, you can't power a 14-20 system from a 14-30 receptacle - you need to have overcurrent protection at 20A for your 14-20 system with #12 wire.
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Chris Delcambre

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Re: Stage Stringers
« Reply #3 on: June 06, 2014, 03:53:19 pm »

If you mean using 2 5-15P to an L14-20R, no.  There are thee issues (apart from the fact that it is illegal): 

- If a device is on, there is some impedance between the hot of circuit A to the hot of circuit B, which means that if you plug in plug A but B has not been plugged in yet, you have put voltage on the exposed male contacts of plug B.

- If there is a wiring error in one of the receptacles you are using - a H->N reversal, you could short a hot to neutral, or if both were backwards, short a hot to hot.

- It is not trivial to ensure that the two receptacles you are using are on opposite phases, meaning that you could potentially be asking for 40A of return current on your one neutral wire.

This is an interesting idea, but not good unless you're sure you always have a distro.  BTW, you are using common-trip breakers for this in your distro, right?  :)

Makes sense... And yes I am using common trip breakers...
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Tom Bourke

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Re: Stage Stringers
« Reply #4 on: June 06, 2014, 04:14:00 pm »

Any one know the code compliance of making a single nema 5-20 Plug to nema 14-20 Socket adaptor where you simply tie the two 14-20 hots together?  The result would be, in this case, a single circuit stringer with extra wires carrying the hot side.  Any 208/240V loads connected between hots on the 14-20 would get 0V and thus not work.
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Brian Adams

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Re: Stage Stringers
« Reply #5 on: June 06, 2014, 05:14:47 pm »

Any one know the code compliance of making a single nema 5-20 Plug to nema 14-20 Socket adaptor where you simply tie the two 14-20 hots together?  The result would be, in this case, a single circuit stringer with extra wires carrying the hot side.  Any 208/240V loads connected between hots on the 14-20 would get 0V and thus not work.

You can split one circuit to both hot wires in the cable, that's no problem. You might consider putting a 5-15 plug on the adapter instead though, just so you don't limit yourself too much. They'll both handle the same amount of current.

Any reason you're not making 3 circuit stringers? I see those a lot more often than 2 circuit stringers. Do you only have a single phase distro?
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Tom Bourke

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Re: Stage Stringers
« Reply #6 on: June 06, 2014, 05:45:06 pm »

You can split one circuit to both hot wires in the cable, that's no problem. You might consider putting a 5-15 plug on the adapter instead though, just so you don't limit yourself too much. They'll both handle the same amount of current.

Any reason you're not making 3 circuit stringers? I see those a lot more often than 2 circuit stringers. Do you only have a single phase distro?
I am not the OP.  However I DO have L14-20 stage stringers and a 50A single phase distro.  For the most part it is a great setup.  On the smaller gigs I just use single circuit stringers.  I never did make the above adaptor but I am considering it.  These days I try to stay as code compliant as possible.

I think the 3 phase vs single depends on your area and venues.  In WI where I use to live 3phase in small and medium venues was nonexistent.  50A single phase or wall power was easy.  I did put in 3 phase infrastructure and stringers at one of my house gigs.  It was mostly used for motors, moving lights and LEDs in a theatre.
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Re: Stage Stringers
« Reply #6 on: June 06, 2014, 05:45:06 pm »


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