3 phase equipment

[wireperson]

1. what happens if I feed a 3 phase condensing unit using a 3 pole breaker in a single phase panel? its just causes phase imbalance on panel? or damage the CU?.


2. what happens if the same condensing units is fed by a 2 pole breaker , you left 1 of the phases without wire.

I was working in a CU today and found that they have 2 CU's (both 3 phase). 1 of them (cu1)is being fed from a 3 phase panel using a 3 pole breaker. . .that's ok .The other one (cu2)is fed from a single phase panel and the missing phase is shared from cu1 , besides they are unsing single pole breakers on this 1 phase panel . That's the reason of the 2nd question , because when they turn off the breaker on cu1 the cu2 will be missing 1 phase. . . . . . any thoughts?

 

[Dennis Alwon]

My thought is that the install is illegal.

 

[LarryFine]

Mine is that it's insane.

 

[wireperson]

that's only 1 of the many violations that I found at this location . . . .anyway ,can you guys answer the 1rst question?

 

[chris kennedy]

can you guys answer the 1rst question?

Are you sure you want to open the 'phase angle' can of worms?:smile:

 

[480sparky]

I think either one would have the same effect as 'ordinary' single-phasing.

 

[cadpoint]

Since its a motor for the condensor, yes it not correct to be only on a breaker usually its a fused application with anything from 125 to 200%, Dual element time delayed, etc... I'm not sitting with a Code book ...
Someone please state a Code Article ...

In most cases your in-rush of current caused buy a motor will overwelm a three pole breaker.

Now you can breaker the branch circuit thats infront of the disconnect, but this doesn't seem to be the case.

 

[wireperson]

it does have a fused disco . but I wonder what would happen if fed from a single phase using 3 pole breaker. just curious . .

 

[cadpoint]

I missed that, you'd wear out the Breaker... it'd go pop ...

 

[brian john]

If control voltage (phase monitor or improper primary voltage on a control transformer) did not stop the unit from starting, I would think you would have single phasing of the compressor which would result in damage to the compressor.