150 KVA TRASF 480V 3PH PRIMARY 120/208V 3PH 4W SECONDARY

[stanleycochran]

150 KVA TRANSFORMER.
WHERE DOES THE SECONDARY OVERCURRENT PROTECTION NEED TO BE LOCATED ? THE SITUATION I HAVE IS THE PRIMARY PROTECTION WILL BE LOCATED AT THE TRANSFORMER, THE SECONDARY WILL BE LOCATED APPROXIMATELY 120' AWAY. IS THIS ACCEPTABLE? OR IF I FUSE THE PRIMARY OVERCURRENT AT 125%, I AM NOT REQUIRED TO HAVE OVERCURRENT PROTECTION ON THE SECONDARY SIDE.
ALSO, THE TRANSFORMER IS 150 KVA WHICH REQUIRES THE ROOM TO BE 1 HOUR FIRE RATED OR THE TRANSFORMER INSULATION TO BE CLASS 155 OR HIGHER. IS THIS CORRECT?

 

[don_resqcapt19]

Re: 150 KVA TRASF 480V 3PH PRIMARY 120/208V 3PH 4W SECONDARY

Stanley,
There is no specified location for the transformer overcurrent protective device, however, the secondary conductors must be protected at their source of supply or per one of the tap rules in 240.21.
Don
PS please don't use all caps, thanks

[ December 01, 2003, 02:04 PM: Message edited by: don_resqcapt19 ]

 

[steve66]

Re: 150 KVA TRASF 480V 3PH PRIMARY 120/208V 3PH 4W SECONDARY

Also, be very careful using 240.4 (B). This paragraph allows protecting wire with the next size larger breaker as long as it is 800A or less. (For example, 380 amp wire could be protected with a 400 amp breaker). However, most if not all the tap rules prohibit this.

Steve