I'm in a pickle. We are working a 165 unit apartment project and the HVAC and plumbing was changed from gas to electric. Not on the drawings mind you, but at the field level. My concern is that even though 80A of load per unit has been added to this project, the builder is NOT willing to upgrade the services - to the buildings or the units.
Based on the previous HVAC loads being gas, the main breakers for the units are 100 amp at 240V.
Per the engineer, the electrical loads are as follows:
3,840 = Square footage average = 1280 square feet x 3
3,000 = Appliance
8,000 = Range (seems low and need to verify)
4,500 = Electric Hot water tank
1,500 = Washer
5,000 = Dryer
800 = Disposal
740 = Dishwasher
300 = Range hood
27,680
10,000 = First 10KVA at 100%
7,072 = Remainder at 40%
6,500 = Electric furnace greater than heating (10KW x .65)
23,572/240 = 98.21 amps
So, the engineer is saying the 100 amps is adequate.
But, there is also a heat pump. Couldn't the 30A, 240V heat pump and the aux. furnace also cycle together at times (althought the same engineer added a not stating that they are to be set up not to)? Also, there is a main breaker IN the furnaces, which is 60 amp. If the furnace has a 60A main, and we are feeding it with a 60 amp circuit, wouldn't we have to calculate its load at 14,400 in lieu of 10kw?
In short, I have to warranty this work. I have to ensure this work and I have to stand by this work.
If the furnace was running while someone was doing the laundry (hot water tank would be cycling also), it would trip the main.
If someone was cooking and the furnace was running and a few lights were on, it could trip the main.
In short, there are SOOO many variations that are real that could trip the 100 amp main that it doesn't pass the gut check for me. I have told the builder this but they can't be bothered.
Also, I thought electric furances were considered constant load and had to be calculated at 125%? The engineer is taking actual load based on the size of the elements and multiplying by 65%.
Any feedback for peace of mind would be appreciated.
Thank you.
Based on the previous HVAC loads being gas, the main breakers for the units are 100 amp at 240V.
Per the engineer, the electrical loads are as follows:
3,840 = Square footage average = 1280 square feet x 3
3,000 = Appliance
8,000 = Range (seems low and need to verify)
4,500 = Electric Hot water tank
1,500 = Washer
5,000 = Dryer
800 = Disposal
740 = Dishwasher
300 = Range hood
27,680
10,000 = First 10KVA at 100%
7,072 = Remainder at 40%
6,500 = Electric furnace greater than heating (10KW x .65)
23,572/240 = 98.21 amps
So, the engineer is saying the 100 amps is adequate.
But, there is also a heat pump. Couldn't the 30A, 240V heat pump and the aux. furnace also cycle together at times (althought the same engineer added a not stating that they are to be set up not to)? Also, there is a main breaker IN the furnaces, which is 60 amp. If the furnace has a 60A main, and we are feeding it with a 60 amp circuit, wouldn't we have to calculate its load at 14,400 in lieu of 10kw?
In short, I have to warranty this work. I have to ensure this work and I have to stand by this work.
If the furnace was running while someone was doing the laundry (hot water tank would be cycling also), it would trip the main.
If someone was cooking and the furnace was running and a few lights were on, it could trip the main.
In short, there are SOOO many variations that are real that could trip the 100 amp main that it doesn't pass the gut check for me. I have told the builder this but they can't be bothered.
Also, I thought electric furances were considered constant load and had to be calculated at 125%? The engineer is taking actual load based on the size of the elements and multiplying by 65%.
Any feedback for peace of mind would be appreciated.
Thank you.