grounded delta

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jonsender

New member
Location
California
Recently I came across a 480V 3-wire delta service with one leg grounded. An associate at Edison told me that 480V corner ground systems are illegal but 240V ones are not. This is the first time I have seen a 480V corner ground. I could not find anything on the code for it. Article 100, definitions mentions 480V 3-wire open grounded systems. What should we do with this service? And why would a 480V corner ground be legal when a 240V is not?
 

scott

Member
Location
Colorado
Re: grounded delta

The NEC does not generally prohibit either installation. There may be a local amendment in your area. Look at art. 250 part II for specifics.

It should be noted that there are occupancy limits for voltages (see 210.6) that may limit the 480V as well as the 240V corner grounded systems. Both would be nearly worthless in a residence, for example.

Enjoy your day!
 

rb

Member
Location
Tennessee
Re: grounded delta

210.6(d) would prohibit a 480 volt corner grounded delta from supplying luminaires located inside of a building.
 
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