Clearer understanding of Phase relationships

[Tod]

I am not an Electrician but my job requires me to have a basic working knowledge.
My facility is fed by 480 3Ph, 600 Amp service. One of the 480v 200Amp circuits is to a stepdown transformer to 208 3Ph, which feeds a 208 Panel.

A 100Amp panel is one of the feeds off this 208 load center. The 100A main breaker is 3 pole. One of the loads on this panel is an airconditioning unit that is fed off a 2 pole breaker 60A. All the panel breakers are marked 120/240.
Is the airconditioner 1Ph or 3Ph? In other words if you use 2 legs from a 208 3 Ph panel is this now 1 Ph?

 

[augie47]

When one uses 1 phase (and a grounded conductor) or two phases (with or without a grounded condcutor) of a 3 phase system, those circuits are considered to be "single phase".

 

[jim dungar]

The number of phases in a circuit can often be determined by simply looking at the number of Line-Line voltages available.

 

[LarryFine]

Tod, welcome to the forum!

When you grab two hots from a 208v 3ph source, you have two 120v-to-neutral 1ph sources (if you bring in the neutral, too), and one 208v 1ph source.

By the way, breaker and panel ratings, such as 120/240v, are maximum ratings, not absolutes, and refer to line-to-ground and line-to-line, respectively.