Cable and Recepticle Ratings

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Richard McLawhorn

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Mar 16, 2011
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For those of you electricians out there. When i have a Nema L14-30 connector rated at 30 amps and a length of 10/4 SO cable that also says 30amps on it, does that mean 30 amps total (15 amps per leg) OR 30 amps per leg?

My gut tells me that it's 15A per leg but i just want to check. FWIW the cable is going to a truss box with 2 15A edison circuits, 1 per leg of the 220, with common neutral and ground.

Thanks!
 
Richard McLawhorn said:
For those of you electricians out there. When i have a Nema L14-30 connector rated at 30 amps and a length of 10/4 SO cable that also says 30amps on it, does that mean 30 amps total (15 amps per leg) OR 30 amps per leg?

My gut tells me that it's 15A per leg but i just want to check. FWIW the cable is going to a truss box with 2 15A edison circuits, 1 per leg of the 220, with common neutral and ground.

Thanks!
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This is a phone reply, so light on the details...

I'm no sparky, but it's 30a per leg. Each leg to neutral is also 120, each leg to leg is 240 from a split phase (or delta) service.

You need a breaker or other ocpd to use the feed with 15a wiring and devices.
 
Re: Cable and Recepticle Ratings

Richard McLawhorn said:
For those of you electricians out there. When i have a Nema L14-30 connector rated at 30 amps and a length of 10/4 SO cable that also says 30amps on it, does that mean 30 amps total (15 amps per leg) OR 30 amps per leg?

My gut tells me that it's 15A per leg but i just want to check. FWIW the cable is going to a truss box with 2 15A edison circuits, 1 per leg of the 220, with common neutral and ground.

Thanks!
Click to expand...

It's rated for 30A per leg, which is the same as 30A total when you do the math. Also, 10/4 is only rated for 30A if you don't need to consider the neutral as a current-carrying conductor (not true if you have dimmer loads, for example).
 
Re: Cable and Recepticle Ratings

Marlow is correct - an L14-30 is a 30A 240V cable - you get 30A at 240V with a neutral plus ground. You can use 30A X 2 for line to neutral loads, giving you "60 amps" at 120V, but this is still really a 30A circuit.

As Marlow mentioned, if you're putting Edison outlets on this you need breakers at 15A or 20A somewhere in the chain.
 
Re: Cable and Recepticle Ratings

TJ Cornish said:
Oops - Apparently Rob and I were typing at the same time.

The NEC section which governs portable cord use and ampacity is NEC section 400:
http://galileo.phys.virginia.edu/research/groups/hep/aag/70-A2010-ROPDraft.pdf
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Trying to navigate that document was killing me. This is easier:

attachment.php
 

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Re: Cable and Recepticle Ratings

TJ Cornish said:
Marlow is correct - an L14-30 is a 30A 240V cable - you get 30A at 240V with a neutral plus ground. You can use 30A X 2 for line to neutral loads, giving you "60 amps" at 120V, but this is still really a 30A circuit.

As Marlow mentioned, if you're putting Edison outlets on this you need breakers at 15A or 20A somewhere in the chain.
Click to expand...

Thanks Guys,
This was definitely the answer that i was looking for. I knew that i needed to stay with the single throw 2 pole 15A breakers if i am putting edisons on the other end. I would put the 15a breakers on the truss box except that the truss box assembly were pre made with no place for breakers in the box. I guess they were designed to be on properly breakered circuits.

I have always been slightly confused about the rating on the 240v devices. I guess i need to find a source to learn some more about 240v. Any suggestions?

Thanks Again!
 
Re: Cable and Recepticle Ratings

Richard McLawhorn said:
Thanks Guys,
This was definitely the answer that i was looking for. I knew that i needed to stay with the single throw 2 pole 15A breakers if i am putting edisons on the other end. I would put the 15a breakers on the truss box except that the truss box assembly were pre made with no place for breakers in the box. I guess they were designed to be on properly breakered circuits.

I have always been slightly confused about the rating on the 240v devices. I guess i need to find a source to learn some more about 240v. Any suggestions?

Thanks Again!
Click to expand...

For the specific application, I don't fully follow. You don't have any other source for regular Edison circuits than the l14-30? Is the truss input locking connectors (ie l5-15 or l5-20)?

As far as learning goes, this book is great and very accessible: http://www.amazon.com/Electricity-Entertainment-Electrician-Technician-Richard/dp/0240809955

The hurdle for most people understanding both electricity and sound is phase. With a really good grasp of phase, many electrical concepts become more clear. The authority on phase in audio is Bob McCarthy and his book is great, but not really a casual read: http://www.rationalacoustics.com/store/books/sound-systems-design-and-optimization.html

You could also head over to the old PSW and read just about anything by Lee Patzius (sp?) which is free and informative.

As starter, I'm sure there are also quite a few online general-information type sources for US AC power info.

Cheers,

Marlow
 
Re: Cable and Recepticle Ratings

The Truss Box has a non-typical 30a locking connector that even my local electric supply shop said that they have to special order. I don't recall offhand what the code on the connector is. I had replaced the male end of the cable that comes from the truss box with an L14-50 and put a L14-50 Recepticle on my distro however, i wanted to change those connectors over to a locking connector and also to a connector that is not as bulky. I also had another use for my L14-50 connectors and recepticle. Seemed like the right time to change the connectors on the Distro and the cable. I had already used the 15a breakers because i knew that was the limit on the edison recepticles, so it is just a matter of changing the parts.

The main reason for the use of these is for ease of use and making use of what i have in my inventory. The cable for this truss box is over 150 feet long and provides (2) 15 amp circuits on my truss. It was given to my when my church was doing some cleanout and i have no other use for 150 feet of 10/4 cable. This box also doubles as my FOH power source for audio gigs. Hope this shines some light on the purpose of my thoughts.

Thanks!
 
Re: Cable and Recepticle Ratings

Richard McLawhorn said:
I had replaced the male end of the cable that comes from the truss box with an L14-50 and put a L14-50 Recepticle on my distro however, i wanted to change those connectors over to a locking connector and also to a connector that is not as bulky.
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L14-50 IS a locking device, which is what the "L" signifies. it's 50A 250V.

a simple 14-50 would be a straight-blade/non-locking 50A 125/250V configuration.

fyi...

R~
 
Re: Cable and Recepticle Ratings

Richard McLawhorn said:
The Truss Box has a non-typical 30a locking connector that even my local electric supply shop said that they have to special order. I don't recall offhand what the code on the connector is. I had replaced the male end of the cable that comes from the truss box with an L14-50 and put a L14-50 Recepticle on my distro however, i wanted to change those connectors over to a locking connector and also to a connector that is not as bulky. I also had another use for my L14-50 connectors and recepticle. Seemed like the right time to change the connectors on the Distro and the cable. I had already used the 15a breakers because i knew that was the limit on the edison recepticles, so it is just a matter of changing the parts.

Thanks!
Click to expand...


Just for Reference: the L14-50 is the Cali series plugs , the L14-50 isn't a NEMA registered plug.
Plug: CS6365C
Connector: CS6364C
Receptacle: CS6369
Inlet: CS6375
 
Re: Cable and Recepticle Ratings

Rob Spence said:
Not many places stock L14-50 connectors.
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I think the confusion is that the CS connector is the defacto standard while the L14-50 is a rare beast. I know I have never seen one. For SR applications, using whatever is commonly available makes sense.

Richard,

I still don't completely understand your setup, but having a 50 amp plug on wiring and devices rated for 15 amps is asking for trouble, even if you use it safely, the potential for someone else do hook it up in a way that could be dangerous would make me look for other options. Why not just use L14-20? No additional breakers are needed on the truss and nothing can be connected in a way that could be dangerous if using a standard L14-20 outlet.
 
Re: Cable and Recepticle Ratings

Marlow Wilson said:
I think the confusion is that the CS connector is the defacto standard while the L14-50 is a rare beast. I know I have never seen one. For SR applications, using whatever is commonly available makes sense.

Richard,

I still don't completely understand your setup, but having a 50 amp plug on wiring and devices rated for 15 amps is asking for trouble, even if you use it safely, the potential for someone else do hook it up in a way that could be dangerous would make me look for other options. Why not just use L14-20? No additional breakers are needed on the truss and nothing can be connected in a way that could be dangerous if using a standard L14-20 outlet.
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Provided the L14-20 is appropriately current limited with a two-pole 20 amp breaker.

Alternatively, you could use some pushbutton panel-mount breakers in a breakout quad box, but you have to size the wire feeding that appropriately for the circuit. So, if you're looking at feeding some Edisons with a 50-amp circuit, you're going to have to feed your quad with 6 gauge or larger, and then use breakers to get your 20 or 15 amp limit. This could prove to be extremely expensive and unnecessary compared to just changing the feeding breaker...
 
Silas Pradetto said:
Provided the L14-20 is appropriately current limited with a two-pole 20 amp breaker.

Alternatively, you could use some pushbutton panel-mount breakers in a breakout quad box, but you have to size the wire feeding that appropriately for the circuit. So, if you're looking at feeding some Edisons with a 50-amp circuit, you're going to have to feed your quad with 6 gauge or larger, and then use breakers to get your 20 or 15 amp limit. This could prove to be extremely expensive and unnecessary compared to just changing the feeding breaker...
Click to expand...

He says he's using 2 pole, single throw 15a breakers at the moment.
 
Re: Cable and Recepticle Ratings

Marlow Wilson said:
He says he's using 2 pole, single throw 15a breakers at the moment.
Click to expand...

I must have missed that. If he can switch those to a 2-pole 15 amp breaker, and that breaker is in fact upstream of his 50 amp receptacle, then there is no code violation. In fact, as long as the receptacle is rated for at least 15 amps per leg, then it doesn't even matter what it is.

Let me add, though, that making a quad with a 50-amp plug to Edisons still needs breakers, because there is no guarantee that it will be plugged into an appropriately 15-amp-breakered 50-amp receptacle.

It might have been mentioned before, but why not just change the receptacle out for something else, like double duplex receptacles? The wire is already there, it will be oversized for the new circuits, but it will still only be a 30 minute job for any electrician.
 
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