VD Calc

[Alwayslearningelec]

If you had a breaker feeding a 400A panel and panel had spares so you wouldn't now true load in future would you always use 400A as the load in your calculation even though it would never really have a load on it of 400A? Thanks

 

[Dennis Alwon]

"If you knew the load would never have 400 amps on it".... How would you know this? I would find out what the load was on the panel and take a good guess at the max but in most cases I would probably use 400 amps. If you were feeding a piece of equipment that was only 225 amps and no other loads then I would use 225 amps.

I guess it depends on the situation but you can't go wrong with figuring the max

 

[Dsg319]

If you had a breaker feeding a 400A panel and panel had spares so you wouldn't now true load in future would you always use 400A as the load in your calculation even though it would never really have a load on it of 400A? Thanks

You’ll probably receive several different answers. Varying from using the calculated load of which you have now to using the full 80%capacity of the rated 400amp breaker.

Me personally i would in simple terms explain to the client both options and probably myself push for the above and beyond and figure for 320amperes.