How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rich Your Own Question
Rich
Rich, Master Electrician
Category: Electrical
Satisfied Customers: 1801
Experience:  Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain
5098113
Type Your Electrical Question Here...
Rich is online now
A new question is answered every 9 seconds

I HAVE A 3 PHASE 208 VOLT 5 TON ROOFTOP A.C. UNIT IT HAS A

Resolved Question:

I HAVE A 3 PHASE 208 VOLT 5 TON ROOFTOP A.C. UNIT IT HAS A RUNNING LOAD OF 80 AMPS WITH A 100 AMP FUSED DISCONNECT THE PROBLEM IS IT HAS A FEEDER TO THE DISCONNECT THAT IS 3-1/0 CU.THHN CABLES ON A 200 AMP BREAKER. iS IT PERMISSABLE TO KEEP THE 200 AMP BREAKER OR DOES IT HAVE TO BE CHANGED.
Submitted: 5 years ago.
Category: Electrical
Expert:  Rich replied 5 years ago.

Rich :

Hello .. you are within code with what you have described

Rich :

the 200 amp breaker is too big for the circuit ,, but the circuit is protected with the 100 amp fused disconnect at the AC unit

Expert:  Rich replied 5 years ago.
When you return, please post here and the forum will send me an alert .. Thanks .. Rich
Customer: replied 5 years ago.

Rich are the 1/0 wires large enough in view of the code requirement that says you can derate the wire size 125% for a motor load.

Expert:  Rich replied 5 years ago.

Yes .. I believe the 1/0 are good for about 150 amps ,, off the top of my head ..

 

you did not mention a ground wire with the feed wires ???

 

Customer: replied 5 years ago.
Rich the feeders are in a emt conduit and they have a bonding wire in the sealtite conduit to the unit. but you think the 200 amp breaker should be changed to a 150 amp.
Expert:  Rich replied 5 years ago.
Thats is fine .. if it makes you feel better .. the feeders are protected at the other end .. at the AC unit by the 100 amp fused disconnect ..
Rich and other Electrical Specialists are ready to help you