Location of 480 to 208 transformer

[opie]

Medical practice with need for 112 kva, 480 to 208 3ph transformer. Location choices are in the staff breakroom on the floor in the corner near the two panelboards. Or in the ample plenum area above the breakroom. It would be under 10 feet away from the panelboards in both locations. No closet planned to house the transformer, but a free standing screen of some type has been suggested to hide the transformer and panelboards from the staff while they are in the breakroom. Also in the room is a sink area, microwave and refrigerator. HVAC conditioned space in the breakroom. Plenum is a HVAC plenum-return area so it will be conditioned somewhat.
Question is what is the best location to mount the transformer? Thanks.

 

[barclayd]

450.13 Requires transformers to be 'Readily Accessible'.
Putting it above the ceiling would be a violation.

 

[DBack Elec]

Medical practice with need for 112 kva, 480 to 208 3ph transformer. Location choices are in the staff breakroom on the floor in the corner near the two panelboards. Or in the ample plenum area above the breakroom. It would be under 10 feet away from the panelboards in both locations. No closet planned to house the transformer, but a free standing screen of some type has been suggested to hide the transformer and panelboards from the staff while they are in the breakroom. Also in the room is a sink area, microwave and refrigerator. HVAC conditioned space in the breakroom. Plenum is a HVAC plenum-return area so it will be conditioned somewhat.
Question is what is the best location to mount the transformer? Thanks.

A 112 KVA transformer at 208 volts is 300 amps. I don't understand why you would that much power in a breakroom. Most breakroom panels are 100 amp. Maybe if you look at what is being powered you may find a better route.

 

[opie]

Good point about accessibility. I have seen transformers mounted high lots of times but they were visible in a dedicated electrcial closet and accessible by ladder, and not above a drop ceiling. As for the comment about load, the breakroom is the only place left in med office, it seems, to mount the panels and transformer. The "load" is for the medical practice which is for 9 rooms worth of equipment. I am a specialty electrical contractor (low voltage) and not a general electrical contractor. I was only observing this design for an owner/relative of mine. I just felt that having a humming, heat-generating transformer nearby a breaktable where the staff will be resting did not seem right to me, somehow. Any advice for locating transformers like this in and around people? Any code separation requirement between people sitting and a large transformer like this? Thanks again.

 

[jatrottpe]

Providing it meets all the working clearance requirements the Break room would make sense from a technical stand point.
From an ergonomic (sp?) standpoint the constant hum of the transformer (assuming dry type ventilated for commercial use) will get a lot of noise complaints from the staff, especially a non-industrial staff. And they may want it to be relocated in the not to distant future.

 

[480sparky]

450.13 Requires transformers to be 'Readily Accessible'.
Putting it above the ceiling would be a violation.

Unless it is a drop ceiling.

 

[barclayd]

Unless it is a drop ceiling.

The ceiling type is irrelevant. Article 100 defines 'Readily Accessible' ( " ... without requiring .... portable ladders ... " )
Article 450.13 sets a 50kva limit for installation above a suspended ceiling.

 

[opie]

OK. Thanks for comments. I also spoke to a power engineer. He says that <75KVA can go above a ceiling if it is accessible (arrangements made for ladder and plenty of room, etc.) BUT, no transformer can go into a plenum ceiling, which this situation is. So, my owner/relative will have to live with the heat and noise of the txfrmr for his staff in the breakroom, or else, give up their breakroom bathroom, use the main one down the hall for all the floor's tenant's and use the space available where the bathroom was to put in the transformer (with proper clearances) and panelboards and sufficient cooling and/or ventilation.

Thanks.

 

[winnie]

Transformers don't have to be noisy, and don't have to produce much heat. The noise and heat load of a transformer are the result of a design trade-off between operational characteristics and cost. I am sure that though proper application of dollars you could have a transformer suitable for the break room environment.

I have no experience specifying or ordering custom mains transformers, but I recall coming across several manufacturers while I was looking for other items for my electric motor work. I am sure that someone here could point you to a supplier that will provide an appropriate transformer.

Also keep in mind that proper mounting of the transformer and mounting of the core inside of the transformer enclosure can make a large difference in sound transmission.

-Jon

 

[infinity]

The ceiling type is irrelevant. Article 100 defines 'Readily Accessible' ( " ... without requiring .... portable ladders ... " )
Article 450.13 sets a 50kva limit for installation above a suspended ceiling.

It also sets a limit as to not being required to be readily accessible.

 

[kenaslan]

Don't forget to have the transformer mounted on noise isolation pads that will help reduce noise, and to loosen the shipping bolts inside

 

[kbsparky]

Put it in the breakroom. That way, they can heat their lunches merely by putting the lunch bag(s) on top of that transformer. :grin:

Might as well use that excess heat for something....

 

[iwire]

I was doing electrical work in an ice cream factory.

They had a large transformer in an employee area....the employees liked it as they put their winter boots, hats and gloves inside the transformer to keep them warm as most of the building was below freezing. :roll: