120/208 volt 3 phase feed but need 208 volt single phase to power up water heater

Status
Not open for further replies.
Hello, Everyone

I have a situation that I would like some help and feedback with.
Here is the description of what I got dragged into.
Large commercial building, needed a new water heater. The old water heater was fed by 208 volt 60 amp 3 phase with a 60 amp fused disconnect at the water heater and a 60 amp breaker in the stand up section in the electric room.
The plumbers installed a new water heater and in trying to save the customer money or to make money or some stupid reason, they installed a water heater that is residential rated and operates on either 240 volt or 208 volt single phase.
They want me to convert the 3 phase 208 v to single phase 208 v to power the water heater instead of installing the commercial rated one.
This building is a very large air frieght and cargo shipping center and the electric rooms are powered with only 120/208 v 3 phase and 277/480 v 3 phase systems.
The amperage is close enough to not need new wires pulled for size and rating, so my thoughts for the easiest way to do this would be replace the 3 pole 208 volt breaker with a 2 pole breaker and get 208 off the buss bars that the breaker bolts onto and since the water heater needs no neutral wire only two hots and a ground, I can make the connection and call it a day.
Is that a good way of doing that or not?
The water heater is a dual element (upper and lower) that run simultaneously so there is no concern of one leg being unbalanced and causing problems. But is it a hack fix that I don't need to be doing just to help the plumbers in their screwed up situation? Is there a cost effective alternative? The commercial water heater that should have been installed would cost between $2k and $3k so, as long as I can do the job for around a grand or so they will be happy. And I would like to help them if I can.
Oh, the plumbing company gives me a lot of business and the owners have been close family friends for over forty years and want to help but not at safety or my business expense.
Thanks for your help, in advance
 
Just use two of the conductors cap the other one and install the correct size breaker.

Roger
 
From an electrical perspective, your solution looks fine to me. But from the perspective of the building's owner or tenants, the plumber's substitute unit may not provide the amount of hot water that is needed. Add to that the fact that if the unit is capable of operating at 240 volts, then operating it at 208 volts (even though this is OK'd by the manufacturer) will mean it will only provide 75% of its rated power for heating water. That might also cause a problem for the owner or tenants.
 
Thanks, Roger. That's what I thought. The breaker size is good at 60 amps but I can't use the 3 pole breaker with just the two wires, I should install a 2 pole shouldn't I?
It is perfectly fine to use the three pole breaker.

Roger
 
From an electrical perspective, your solution looks fine to me. But from the perspective of the building's owner or tenants, the plumber's substitute unit may not provide the amount of hot water that is needed. Add to that the fact that if the unit is capable of operating at 240 volts, then operating it at 208 volts (even though this is OK'd by the manufacturer) will mean it will only provide 75% of its rated power for heating water. That might also cause a problem for the owner or tenants.

That was something I brought up to the plumber and the building maintenance man. They both replied that the water heater operating at 75% would be sufficient to supply the restrooms and kitchen and janitorial needs. There are no cafeterias or showers etc...
So, if they aren't concerned I am okay with it
 
That was something I brought up to the plumber and the building maintenance man. They both replied that the water heater operating at 75% would be sufficient to supply the restrooms and kitchen and janitorial needs. There are no cafeterias or showers etc...
So, if they aren't concerned I am okay with it
Sounds like original was possibly overkill, or no longer has demand it once did.
 
Status
Not open for further replies.
Top