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 Mike Your Own Question
Mike, Master Electrician
Category: Electrical
Satisfied Customers: 1425
Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
Type Your Electrical Question Here...
Mike is online now
A new question is answered every 9 seconds

I have a 208v to 480v transformer lot lighting, and when I

Customer Question

I have a 208v to 480v transformer for parking lot lighting, and when I turn the lights on it blows the main 200A breaker. When test I get 480 phase to phase but also 480 to ground on 2 legs and 0 to ground on leg 3. There are 12 2 pole breakers in the panel, I can leave a certain 3 breakers off and have no problem but when I turn breaker (1,3) on it trips the main. Also the other two breakers won't have amperage on either one unless they're both on, and if you turn both on, the main trips after a few seconds. Not a lot of experience with transformed voltage up to 480 or with 480 lighting. Help!
Submitted: 1 year ago.
Category: Electrical
Expert:  ProGrade replied 1 year ago.

Hi, welcome to

Can you send the make & model of the x-former (picture of data plate is best if possible) along with a sketch of how you have it wired?

Thank you Ken

Expert:  ProGrade replied 1 year ago.

Just checking in, can I be of any assistance on your project? Thanks