wiring and voltage drop

[electricmason86]

My comrades and myself are having a discussion about voltage drop and wiring, I am running #8 to a 7 !/2 hp motor rated at 8.67 amps we are having problems terminating the wires under the lugs of the motor starter due to their size , can I terminate to the starter with #12 and splice to the #8 and change back to #12 on the other end?

 

[winnie]

Yes.

Voltage drop is not like a limiting constriction in a pipe. It is friction all along the length of the wire. So if you have 1 foot of #12, then 1000 feet of #8, then 1 foot of #12 you will have about half the voltage drop vs 1002 feet of #12. (I've not done the exact calculation; #9 would give you half the voltage drop, #8 even less)

-Jonathan

 

[infinity]

Yes. The voltage is 480?

 

[electricmason86]

Yes. The voltage is 480?

yes

 

[infinity]

yes

According the T430.250 the motor has a FLC of 11 amps. That means that the minimum condcutor size would need to be rated for 11*125%=13.75 amps so #12 AWG will work.

 

[augie47]

You can certainly reduce the conductors at any point in thed.e run as long as the smaller conductor is covered by theCP device