GFPE- why required?

[peter d]

Why is GFPE required for large Wye services and not Delta? Is there something about a wye configuration that can deliver huge amounts of fault current that a delta cannot?

(Sorry if this is redundant. I asked this question in an old thread but I couldn't locate it.)

 

[jim dungar]

Re: GFPE- why required?

Actually it is more that the 480Y/277 wye system can deliver a large enough arcing fault current to cause a meltdown of equipment and a fire, but not enough current to open an overcurrent protective device in a timely manner.