Using 208V on NEMA 5-15

[n1ist]

Electrically, it would work OK; it would, however, as you point out, be a NEC violation and a potential safety hazard. If you do decide to go ahead with it. I would tape the plugs into the receptacles and put VERY conspicuous tags on all connections to make it clear to anyone (don't assume that you are the only one to access things, and that you will remember in the heat of an emergency repatch) that those outlets are 208v and should not be touched.
/mike

 

[Chris15]

Electrically it would NOT work OK.

You are talking about using a connector rated for a maximum voltage of 125V at 208V.
As I understand it, the working voltage for a connector is determined working back from the dieelectric breakdown voltage of the connector as established by destructive lab testing.
When you are working at 1.66x the rated voltage, you have severely compromised the safety factors that are built in to establishing the maximum voltage voltage and run a much heightened risk of a voltage fluctuation causing the connector to melt.

You might be lucky and not kill or injure yourself or others. But the odds are that something will go wrong, hopefully it will only be connectors melting together...

 

[STEVETERRY]

Electrically, it would work OK; it would, however, as you point out, be a NEC violation and a potential safety hazard. If you do decide to go ahead with it. I would tape the plugs into the receptacles and put VERY conspicuous tags on all connections to make it clear to anyone (don't assume that you are the only one to access things, and that you will remember in the heat of an emergency repatch) that those outlets are 208v and should not be touched.
/mike

Wait..I'm confused.

Why are we giving advice that amounts to "What you can get away with"?

There is no good reason to allow improper use of a connector at the wrong voltage. It is a major safety hazard that might backfire with significant life-safety consequences.

The correct answer is "Do not do this, under any circumstances". Find the money and time to install the correct connectors. Period.

ST

 

[n1ist]

In most cases, I would agree. I would NOT do this. Howevern there's not much difference between a 5-15 and a 6-15 connector other than the orientation of the pins; I have some that state "250V" on them. Dielectric breakdown on a Hubbell HBL5266C (the first one I pulled the specs on) is 2kV so that's not an issue. As long as the voltage is less than the breakdown voltage it will not cause any melting (excessive current can).

It is a NEC violation to use a product in violation of its listing, so it would not be legal to use a 5-15 at 208v. The major risk is that someone would plug a 110v load into the 208v circuit, which would cause serious safety (fire, shock, or electrocution) issues.

/mike

 

[MNicolai]

You shouldn't be pushing your cables that hard to begin with. It's one thing if you were running a 20A tungsten load on a 100% rated breaker, it's another if you're running arc sources at 20A. The inrush current when you strike the lamp sources, if fixtures were struck simultaneously, could get ugly for you.

I'm curious which gauge your cables are and what the run length is. On 12AWG cable, you can run a 20A load at a 135' cable length and still have 109V. On 14AWG cable at that same length, which shouldn't be used on a 20A load anyway, you would get 103V due to voltage drop.

That all depends on what's in the walls though (or in your power distro depending on what your setup is). If your circuit wiring goes 100' back to your branch panel, that wiring distance also gets included in the calculation for how long of a cable run you can do. In this example, that would mean with 12AWG in the wall for 100', you could only do a cable run at 12AWG for an additional 35' before you would drop below 110V on a 20A load.

You're trying to solve the wrong problem by changing connectors. You should be using lower gauge power cable or dividing your load across multiple cable runs and ideally more than 16A on a 20A circuit breaker unless you know for certain it is rated for a 100% load.

Mind you if you're using a residential-grade extension cable, it could very likely be 16AWG and be especially unsuited for a 20A load, making the voltage drop across your cable even worse.

 

[jroman7]

Mike,

I do agree, the bigger issue is just the load. This is a facility designed for 100% loads, everything is 12/3 wire in good shape, it just has 5-15 connectors on everything.

I did end up just running another circuit to the system and breaking it in half. The distance from the breaker panel to the stage is about 100', it just gets broken up so much once it reaches the lights I think all the connections are causing the voltage drop along with the cable length. When there is no load, i am getting 115V at the fixtures, but when everything is on and loaded it drops way to low.

On a side note, what app are you using for those calculations?

 

[MNicolai]

The app is "VoltageDrop". Don't remember if I paid a couple bucks for it or if it was free, but I'm sure there are more than a couple similar apps in the app store as well.

 

[jhochb]

Good Morning

I use LDCalculator lite. It's not a phone app but it gives you more stuff then you knew you needed.
It is dated as far as the fixture library goes but it has a section to build your own.

Paul Pelletier - LD Calculator

the short list:
Ohm's law
Voltage drop
Phase Ballancing
DMX / Patch list
Truck Pack
Rigging
load list




I used to be a roadie, then I took an arrow to the knee.