Three electrcians all give different answers on service conductor ampacity

[drktmplr12]

"Important research", I said. She went inside and started turning things off.

I think we are experiencing the same life in different instances. :lol:

Unfortunately I have nothing of substance to add to the conversation.

 

[ActionDave]

I think we are experiencing the same life in different instances. :lol:

Unfortunately I have nothing of substance to add to the conversation.

Well, you made my night.

True story by the way.

 

[suemarkp]

3 watts per sq ft x 500 = 1500w -- where do you get 10,000 watts --- oven, cooktop are per his load calc numbers -- more than 4 appliances @ 75% -- 3 phase I"ll recheck anyway but I thought he was just figuring for the unit feeder not the service my bad.

Yes, this is the unit feeder calc. There are two different types of calculations. You're describing the standard calculation, and in that one the oven/cooktop will go in at 8 KVA using the demand table and if 4 appliances a 75% factor could be used (but I don't see 4 that qualify).

For the optional calculation, everything goes in at nameplate, so the oven/cooktop will be 12 KVA. The optional calculation takes the first 10KVA of loads (3 W/sq ft, sm appl circuits, laundry, oven/cooktop,...) at 100% and then everything above that at 40%. So you know with a 12 KVA oven/cooktop you will have at least 10KVA at 100% and 2KVA at 40%. The point being 10 KVA at 208V is 48 amps, so there is no way the calculation could be below 48A with just the oven and cooktop. He said he got 37.5A -- no way to do that even if the only load was this cooktop/oven.

 

[kwired]

Yes, this is the unit feeder calc. There are two different types of calculations. You're describing the standard calculation, and in that one the oven/cooktop will go in at 8 KVA using the demand table and if 4 appliances a 75% factor could be used (but I don't see 4 that qualify).

For the optional calculation, everything goes in at nameplate, so the oven/cooktop will be 12 KVA. The optional calculation takes the first 10KVA of loads (3 W/sq ft, sm appl circuits, laundry, oven/cooktop,...) at 100% and then everything above that at 40%. So you know with a 12 KVA oven/cooktop you will have at least 10KVA at 100% and 2KVA at 40%. The point being 10 KVA at 208V is 48 amps, so there is no way the calculation could be below 48A with just the oven and cooktop. He said he got 37.5A -- no way to do that even if the only load was this cooktop/oven.

But the oven/cook top are likely giving you the 240 volt rating and will draw less @ 208. Info given in OP stated dual voltages for those appliances but only gave one kVA rating - I have to presume for application of the higher voltage rating. I would also presume the dryer will draw less then mentioned because it is also going to be connected to 208 volts.