37kw Insta Heat

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jap

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Electrician
Customer installed a 37kw 240v 1ph insta heat in the mechanical room which is also where the service comes in.
It is a 400 amp service with (2) 200 amp 42 circuit loadcenters.
The unit requires (4) 40 amp 240v feeds to run it.
My question is, instead of taxing all of the load from (1) of the panels, would there be any issue of taking (2) feeds from each panel instead of all (4) from (1) ?

Would not be my 1st choice but its a heavy load regardless of where it comes from.


Thanks,
Jap>
 
Since the equipment load is broken up into four individual loads I don't see a problem. I'm wondering does this unit need a common disconnecting means?
 
infinity said:
Since the equipment load is broken up into four individual loads I don't see a problem. I'm wondering does this unit need a common disconnecting means?
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This will be my first but although the breakers are within sight I was wondering the same thing.
If that would require me to put all the breakers in the same panel and tie the handles together, which would not allow me to split the load.


JAP>
 
jap said:
This will be my first but although the breakers are within sight I was wondering the same thing.
If that would require me to put all the breakers in the same panel and tie the handles together, which would not allow me to split the load.


JAP>
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Or, of course, you could put in a separate fused or unfused four circuit disconnect.
 
GoldDigger said:
Too bad you cannot feed a subpanel from two different source panels. :)
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You could have back when split bus panels were popular.

I don't think this unit would require a single disconnecting means. In fact I don't think it even requires disconnecting means to be within sight but if not in sight would need locking provisions on the disconnect(s).
 
Do you all think all the feeds should come from the same panel?

Jap>
 
I would be more comfortable if they did. But if it would be a lot of extra work (money) to do that I would be comfortable with a label indicating that it is fed from two panels.
On the panel schedule label the breakers as "1 of 4", "2 of 4", etc. just as belt and suspenders, maybe?
 
This unit also indicates if individual conductors are pulled in conduit the same amount are required as if pulling NM.
Showing (4) EGC's.

On a unit with Multiple Feeds is it required to pull an EGC for each Feed if they are in the same conduit or do normal rules apply and only one for the largest circuit?

This is an unusual one for me.


JAP>
 
GoldDigger said:
I would be more comfortable if they did. But if it would be a lot of extra work (money) to do that I would be comfortable with a label indicating that it is fed from two panels.
On the panel schedule label the breakers as "1 of 4", "2 of 4", etc. just as belt and suspenders, maybe?
Click to expand...

So would I, for that reason I would see if you could tap the 400A and install an 8 or 12 circuit subpanel to feed just the Insta hot. That would also help mitigate brown outs on either 200 amp feeder.
 
There is no reason you cant group multiple disconnects for multiple circuits to one unit.

Kind of common for large electric water heaters. I worked at one building that heated the building with hot water supplied by an an electric boiler with three 200 amp 480 volt feeders supplying it.
 
iwire said:
There is no reason you cant group multiple disconnects for multiple circuits to one unit.

Kind of common for large electric water heaters. I worked at one building that heated the building with hot water supplied by an an electric boiler with three 200 amp 480 volt feeders supplying it.
Click to expand...

The breakers are within sight of the insta heat.
I was simply considering not grouping the disconnects in the same panel so all the load wouldn't be on one 200 amp panel.
I'd rather pull 60 amps from each panel instead of 120 from one but with that being said don't like the idea of feeds coming from 2 different panels.

Matter of fact I don't really like the idea of these large insta heats all together.


JAP>
 
jap said:
This unit also indicates if individual conductors are pulled in conduit the same amount are required as if pulling NM.
Showing (4) EGC's.

On a unit with Multiple Feeds is it required to pull an EGC for each Feed if they are in the same conduit or do normal rules apply and only one for the largest circuit?

This is an unusual one for me.


JAP>
Click to expand...
One EGC is fine with me, any more is just a waste of time and material. Use a qualifying metal raceway and you don't need a wire type EGC at all.

jap said:
The breakers are within sight of the insta heat.
I was simply considering not grouping the disconnects in the same panel so all the load wouldn't be on one 200 amp panel.
I'd rather pull 60 amps from each panel instead of 120 from one but with that being said don't like the idea of feeds coming from 2 different panels.

Matter of fact I don't really like the idea of these large insta heats all together.



JAP>
Click to expand...

I'd probably balance the load across both panels myself unless one was definitely loaded more then the other.

I don't like those heaters either, gas instant water heaters are fine but not electric. I guess if someone really wants one I will connect it, but I won't have one as a whole house water heater especially with only ~55 deg F water supply.
 
jap said:
What authority do they have over what load a person puts inside their building on a service that's already established?
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All of it.

For sure part of the service agreement includes language requiring the power company to be notified when the service load is increased.

Also very likely to have limits on what types of loads and maximum KW of a single load.
 
I understand what your saying but I would hope that the load was already calculated to be able to utilize the full 400 amp service.
or maybe I'm thinking about it all wrong.


JAP>
 
jap said:
I understand what your saying but I would hope that the load was already calculated to be able to utilize the full 400 amp service.
or maybe I'm thinking about it all wrong.


JAP>
Click to expand...

The power companies for the most part do not use the service size as a means to determine the load.

Don't get me wrong, I am not calling the power company every time I add a circuit but if I was adding 37 KW all at once to a residential service I might.

If the neighbors lights start dimming the POCO will end up finding out anyway
 
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