Fault Current Calc

[ptonsparky]

I am going to get in the habit of performing the Fault Current calculations at everything but dwelling units. Being forced to by changes in wording of the NEC 110.24(A). "In" vs "At".

MH's calculator does not have a 240 three phase option. Grounded, Ungrounded, or Corner Ground.

Are those systems so rare in other parts of the country?

For those of you that have not tried it yet the Bussmann Fault Current app works pretty slick. You can add the motor contribution, but it does not include L-N fault current.

 

[kwired]

I am going to get in the habit of performing the Fault Current calculations at everything but dwelling units. Being forced to by changes in wording of the NEC 110.24(A). "In" vs "At".

MH's calculator does not have a 240 three phase option. Grounded, Ungrounded, or Corner Ground.

Are those systems so rare in other parts of the country?

For those of you that have not tried it yet the Bussmann Fault Current app works pretty slick. You can add the motor contribution, but it does not include L-N fault current.

I noticed one time I could not use MH's calculator on a open delta system. Most full delta systems I have encountered seem to never require permits and usually had long enough supply conductors I wasn't too concerned with too high of a fault current for the equipment. Otherwise I didn't realize 240 volts three phase wasn't an option in there.

Not knowing the L-N fault current is usually not a big deal either unless you have a really short run to the source. Get past 25 feet or so and it usually will be less then L-L fault current.