Stepdown tranformer questions

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Irocelectric93

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Byrnes Mill, MO
Hello everyone, I'm new to the forum but have been on here as a guest in the past. I wasn't exactly sure where to post this and hopefully someone here can at the very least point me in the right direction. I work for a local university and there's a need for a small water heater in the corner of a particular mechanical room. The water heater is a smaller 120v and I was asked to run the electric for said unit. The only 120v panels in the mechanical room are basically at max capacity and are about 140 ft or more (estimate) from where the tank has already been plumbed and mounted my another mechanic or contractor. About 8 or 9 feet from this water heater there is a 480/277 3 phase lighting panel. I've wired a small stepdown transformer in the past but its been more than 4 or 5 years ago when i was still in trade school. My question is this: is it possible to wire a small (say square D) step down transformer to a small load center for the heater? The heater itself draws 25amps....although assuming this was doable i'm not really sure how i'd come off the panel to the transformer itself. This also begs the question which would be preferable... a 480 to 120v or a 277 to 120v transformer? Also not sure as far as protection of the transformer itself (fuses or a breaker from the panel).
 
Welcome to the forum!

I'm not going to answer your questions directly, but only point to several links!

The general rule of thumb around here is that the group here will help with numbers presented, not work the problem for you.

...My question is this: is it possible to wire a small (say square D) stepdown transformer to a small load center for the heater?...
Click to expand...

Using Square D's web page and searching for ?480 transformer to 240/120? gave this results of PDF's or DXF viewable files.

Now the first of that list shows that a direct transference of power as you desire is available!
The first of the list of the ?480 search? is Here , note the legend up on the right.

Now, to understand how to apply wiring techniques for transformers is the best link by the owner of this web site from his publication in ECM magazine on transformers.

Pay attend that MH does two different sizing at the same time!

I have no profesional association to any products mentioned and all copyrights are to each their own.

Thanks Dennis, Hot off my linked pages. :)
 
Cool, Bob never thought of that... But is the HW rated to handle that?

I'm just thinking they went to a box store and got one and that it's not a resturant
or commerical grade?
 
Even residential grade will have removable/replaceable elements.
But for that voltage?
And can the thermostat contacts handle that voltage?

Tapatalk!
 
Honestly my first recommendation was to just change the water heater to a 277v unit and call it a day, but that was a while back whenever i had first taken over maintaining this particular building. At that time they essentially didn't want to admit that they didn't do their homework and order a heater with the right voltage for the location they chose. However, after pricing 3 phase step down transformers I'm sure they'll change their tune and thats probably the route ill end up going. The panel is an old federal pacific though so sourcing a 277v breaker for it might prove challenging. The long 120v run isn't desirable either from a man hours stand point plus the portion of the mechanical room that i'd be coming from doing that is being renovated so theres no telling where those panels will end up lol. Sometimes getting the "management" to do the right thing is sort of a process. Like let them screw up then me or one of the other guys i work with come along and fix it for them. Thanks guys for the advice and i'll hopefully be on here alot more from here out!
 
Irocelectric93 said:
Honestly my first recommendation was to just change the water heater to a 277v unit and call it a day, but that was a while back whenever i had first taken over maintaining this particular building. At that time they essentially didn't want to admit that they didn't do their homework and order a heater with the right voltage for the location they chose. However, after pricing 3 phase step down transformers I'm sure they'll change their tune and thats probably the route ill end up going.The panel is an old federal pacific though so sourcing a 277v breaker for it might prove challenging.
Click to expand...
I think this is your best option. You'll spend more time and money trying to make the most custom water heater set up in the whole building than you will just buying the right one. Federal breaker is a bit of a wrinkle.
The long 120v run isn't desirable either from a man hours stand point plus the portion of the mechanical room that i'd be coming from doing that is being renovated so theres no telling where those panels will end up lol. Sometimes getting the "management" to do the right thing is sort of a process. Like let them screw up then me or one of the other guys i work with come along and fix it for them.
Click to expand...
140 feet is not that big of a deal. Since it is just a water heater voltage drop is not an issue. Might be cheaper than tracking down a Federal breaker.
Thanks guys for the advice and i'll hopefully be on here alot more from here out!
Click to expand...
If you are promise to use the Enter key more often when you post. It will make them easier to read.
 
Best price the FPE breaker 1st. Sometimes that can be a decision maker :D

I'm imagine cadpoints reference in Post #2 covers all, but to make sure.
a. Size your transformer for the desired load.
b Look at 450.3 to assure you provide proper transformer protection.
c. Look at 240.21(C) to assure you protect the conductors properly.
(Take note that in this case you could make it a two-wire to two-wire install)
d. Look at 250.30 for appropriate grounding rules.
 
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