480 volt single phase

[gsurace]

I have a piece of equipment that requires 480 V single phase. Correct me if I am wrong but is this simply a 2 pole breaker regardless if the system is a Wye, Delta corner grounded or Delta center tapped? Should the breaker be a straight voltage rating versus a slash rated breaker? Any other information needed?

The majority of my 3 phase experience is more commercial on 208/120 systems. Not too much on the industrial side.

 

[JFletcher]

I have a piece of equipment that requires 480 V single phase. Correct me if I am wrong but is this simply a 2 pole breaker regardless if the system is a Wye, Delta corner grounded or Delta center tapped? Should the breaker be a straight voltage rating versus a slash rated breaker? Any other information needed?

The majority of my 3 phase experience is more commercial on 208/120 systems. Not too much on the industrial side.

Yes, a 2p breaker on any of the systems you mentioned would give 480V 1 ph. I am not sure if there are straight rated 480V breakers like there are for 120/240, tho I think all 3p 480V breakers are rated full 480V to ground. There is no 'center tapped delta' 480V system; that would be a wye configuration.

 

[GoldDigger]

Yes, a 2p breaker on any of the systems you mentioned would give 480V 1 ph. I am not sure if there are straight rated 480V breakers like there are for 120/240, tho I think all 3p 480V breakers are rated full 480V to ground. There is no 'center tapped delta' 480V system; that would be a wye configuration.

There is no technical reason not to build a high leg delta system to provide 240-0-240 and 480 Delta at the same time, but that does not mean that the transformers are readily available or that it is even used anywhere.

 

[Jraef]

If your load truly needs 480V single phase, then yes, you simply need a 2 pole breaker.

Whether or not the breaker can be "slash rated" or not is a separate issue having to do with your supply system, nothing to do with the load. So if your supply is 480Y277, you can use any breaker rated 480V to 600V. But if your system is delta (from any conventional source, in deference to GDs post), you cannot use the "slash rated" versions, it must be rated for the full line voltage, and you will typically see those rated as 600V breakers.

And yes, there are lots of low cost breakers, especially from foreign sources, that are rated ONLY for 480/277V, so you cannot use those unless you have a Wye system.

 

[electrofelon]

OP, you did mention corner grounded, and in that case you could even use a single pole breaker.

In practice, you may end up just using a three pole with one pole unused due to cost and/or availability. Recently I needed a two pole 480v i-line breaker and found a very affordable used but good condition three pole so I rocked it.

 

[Iron_Ben]

The state of Louisiana often specifies a single phase 480 volt service for highway lighting. We had a few dozen such services we provided for them. We would use one pole top transformer with a 480 volt center tapped secondary winding instead of the normal 240 volt center tapped winding.

 

[kwired]

Yes, a 2p breaker on any of the systems you mentioned would give 480V 1 ph. I am not sure if there are straight rated 480V breakers like there are for 120/240, tho I think all 3p 480V breakers are rated full 480V to ground. There is no 'center tapped delta' 480V system; that would be a wye configuration.

Square D NF breakers are 277/480 rated breakers. I don't think they have a non slash 480 breaker in that line, so if it is not a 277/480 wye system you must go to the I-Line series to get a straight 480 or 600 volt breakers. I think others have similar series that are also 277/480 rated.

 

[kwired]

There is no technical reason not to build a high leg delta system to provide 240-0-240 and 480 Delta at the same time, but that does not mean that the transformers are readily available or that it is even used anywhere.

We have a lot of open delta 480 volt high leg systems supplying irrigation services. They are composed of pole top 240/480 single phase transformers. Occasionally you find a full delta/ high leg 480 volt system, but those are older services, the POCO only installs 277/480 for new systems if using all three primary lines. Should a storm knock down a pole with full delta high leg on it, it likely gets replaced with a wye system. If just one transformer in the full delta bank fails, they might just replace the one transformer.