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Rich
Rich, Master Electrician
Category: Electrical
Satisfied Customers: 1801
Experience:  Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain
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I am wiring a 480 volt motor. I have a 277/480 volt panel.

Resolved Question:

I am wiring a 480 volt motor. I have a 277/480 volt panel. On the motor there is a low voltage wiring and a high voltage wiring. Do I just use the high voltage wiring diagram or do I need to change some wires in the panel
Submitted: 5 years ago.
Category: Electrical
Expert:  Rich replied 5 years ago.

Rich :

Hello .. lets see if I can help you with this

Rich :

Yes you would us the high voltage wiring diagram shown on the motor

Rich :

can you describe that diagram for me please is this a 3 phase motor is this 3 phase power ??

Customer :

yes, im feeding this motor out of a 277/480 volt panel and its a 3 ph motor

Rich :

OK .. just checking the stupid stuff so I know we are both talking about the same thing

Rich :

the diagram is your guide for wiring the motor

Rich :

you have a 3 pole breaker .. sized for the rated amperage on the motor .. with the correct size wires .. right ?

Customer :

yes

Rich :

does the motor have a motor starter .. ?? and are you OK with that ?

Customer :

yes

Rich :

OK .. anything else that you need to know about this installation ?

Customer :

if I just change the wiring diagram from low voltage to high voltage, will it then run on 480 volts?

Customer :

i dont remember the numbers, but changing like 4 and 7 and 6 and 9 on the motor, like the diagram says, will it then be running on 480 or do I need to change something in the panel?

Rich :

yes .. just like the motor diagram says .. you confirmed that the breaker is a 3pole breakewr in that panel .. so that is 480 3phase .. if you have a different breaker feeding this , then tell me and we can fix that .. ..

Rich :

do you have a multi meter to check the voltage at the starter and the motor .. ?//

Customer :

i have a 3 phase breaker

Rich :

and since you are on 3 phase .. the motor may run in either direction ./. so after you connect the power , you will need to "bump" the motor.. meaning pulse it on just long enough to see which way it is rotating

Customer :

i understand that

Rich :

iof the rotation is right .. you are done .. if it is wrong then you simply swap two of the p[ower leads .. only two .. and that will change the rotation of the motor

Customer :

Basically, low voltage on 277/480 system-the motor is running on 277v and high voltage on 277/480-the motor is running on 480v. Is that correct?

Rich :

anything else ? thoughts .. concerns ? is this a replacement motor .. for a similar motor .. or some different motor at thios location ..

Rich :

the 277 out of your panel is not 3 phase ..

Rich :

so I need to have you confirm the name plate label information for this motor ..

Customer :

the nameplate motor says 230/460v

Customer :

motor nameplate--sorry

Rich :

OK .. but it also says 3 phase or not ... and the amperage .. for each voltage

Rich :

does it have the 3phase symbol on the label

Customer :

yes, it says 3ph and the amps, which i dont remember off hand but its a 5hp motor

Customer :

ground to one leg is 277, correct?

Rich :

I am just wondering why you keep asking me about rewiring at the panel .. if you have a 480 3phase panel and 3 feed wires at the starter and at the motor .. then that little detail makes me wonder

Rich :

yes 277 to ground .. single phase

Rich :

was the previous motor 3phase ?

Customer :

yes

Customer :

im replacing an old motor with a different one

Customer :

hold on

Customer :

i have 3 hots and a ground coming from the 277/480 3 ph panel, if I hook it up according to the diagram on low voltage, it will run on 277volts-correct

Customer :

if I hook it up according to the diagram on high voltage, it will run on 480 volts-correct?

Rich :

the voltage of your panel is 277 volt single phase / 480 volt 3 phase ..

Customer :

so if i wanted to wire lights at 277, i would run 1 hot, 1 neutral and 1 ground--correct

Rich :

if you hook the motor up to this panel with a 3 pole breaker you are using 480 volt 3 phase ,, and you will hook the motor up as the high voltage diagram shows

Rich :

yes for the lights .. 277 volt lights

Customer :

ok, im getting the big picture now.

Rich :

so this is an equipment and lighting panel ... no 120 volt outlets

Customer :

I always thought 277 was 3 phase also, but 277 is kinda like 120 but with a lot more kick

Rich :

you must have a different panel for any 120 volt outlets

Customer :

no 120 volt outets

Customer :

correct, i understand that

Customer :

that makes perfect sense now

Customer :

thanks for all your help

Rich :

OK .. like I said before .. i do not know what your knowledge is .. so need to say some of the stupid stuff so I know we are on the same page

Rich :

s there anything else that you might niot be clear abnout

Rich and other Electrical Specialists are ready to help you

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