4 wire 208/120 plugs

[petersonra]

So I was poking around for a 208 3 phase plug/receptacle good for 60 amps.

I came across nema configuration 18-60R. This has 4 wires in the plug. 3 phases, and a neutral, but no ground. How could one ever use a cord like this without a ground?

 

[petersonra]

So I kept poking around. I can't find a suitable plug for this. Normally I might use a 15-60 but I need that one for a 240 Volt circuit and the customer wants different plugs for the 208 Volt circuit versus the 240 V circuit. Yes, I am designing something that has both a 240 3 phase output and a 208 V 3 phase output. I know, its a little odd. On the bright side it also has a 480 V 3 phase output and a 120 V single phase output.

 

[suemarkp]

NEMA lists an L21-60 (or L15-60 if no neutral needed), but I don't know where you can buy one.

https://www.stayonline.com/product-resources/nema-locking-reference-chart.asp

Or may have to go the pin and sleeve route.

 

[winnie]

Remember that NEMA configurations are common, but as long as you don't exceed voltage limits and don't have the same configuration used in a different way, you don't have to follow their suggested voltage.

IMHO you could use 14-60 for 208V three phase (rather than the NEMA suggested 120/240 single phase) and 15-60 for 240V three phase. But only as long as you don't have 14-60 used for 120/240 single phase elsewhere in the facility.

-Jon

 

[Frank DuVal]

Meltric. But open the wallet!!!!!!

 

[drcampbell]

... NEMA configuration 18-60R ... has ... no ground. How could one ever use a cord like this without a ground?

Presumably, on something that qualifies as double-insulated.
(although I would expect the double-insulated, not-grounded specification to be limited to small 120-volt devices)

 

[zbang]

I think you're into pin & sleeve territory. Whatever it is, requiring a different connector could easily be more expensive than the difference is worth to the customer.

 

[Todd0x1]

Remember that NEMA configurations are common, but as long as you don't exceed voltage limits and don't have the same configuration used in a different way, you don't have to follow their suggested voltage.

IMHO you could use 14-60 for 208V three phase (rather than the NEMA suggested 120/240 single phase) and 15-60 for 240V three phase. But only as long as you don't have 14-60 used for 120/240 single phase elsewhere in the facility.

-Jon

I don't think that exception allows for the designated neutral contact of a device to be used as a hot.

 

[Todd0x1]

I came across nema configuration 18-60R. This has 4 wires in the plug. 3 phases, and a neutral, but no ground. How could one ever use a cord like this without a ground?

They used to use these in hotel ballrooms to supply a hotel provided portable power panel for use by A/V companies. There would be a 6/5 cord going into the plug and the green wire would loop back out the strain relief and have a ring terminal on it which would go under one of the receptacle cover plate's screws. They're still around but fortunately not common anymore. Somewhere I have a 18-60 to camlock adapter....

 

[winnie]

I don't think that exception allows for the designated neutral contact of a device to be used as a hot.

You would need to get the actual insulation rating of the device. If the terminal that the configuration _calls_ neutral has the same insulation as any other conductors, and the configuration is not used elsewhere in the facility in the 'normal ' fashion then IMHO there is no problem.

Jon

 

[Todd0x1]

You would need to get the actual insulation rating of the device. If the terminal that the configuration _calls_ neutral has the same insulation as any other conductors, and the configuration is not used elsewhere in the facility in the 'normal ' fashion then IMHO there is no problem.

Jon

I don't think so. I just looked at the instructions for Hubbell 4 and 5 wire locking devices and the white(silver) screw is specifically designated for grounded conductor. IMHO this would preclude using it for a line conductor.