Electric Boiler Wiring

[Rob Fender]

I'm installing an Electro Industries EB-S-23 electric boiler. Not being an electrician by trade (Architect / own house builder), I have a concern about my 200 amp service, with two 100 amp sub-panels. The electric boiler I'm installing states it uses 94 amps, with two 60 amp breakers and one 30 amp breaker. These breakers are actually mounted on the unit.

In my initial research, the documentation referred to having two 60 amp breakers and one 30 amp breaker. I thought these were breakers in my service panel or sub-panels. I originally was going to run one of the two 60 amp circuits from the 200 amp main, and the other 60 amp and 30 amp from my 100 amp panel in the garage (where the boiler is to be located). But looking at the installation manual, it refers to a single feed (94 amps), which I'm guessing would be equivalent to a 100 amp breaker, two wire, 240 volt, feed coming into the boiler. In that case, I'm also guessing it can be off my 100 amp sub-panel in the garage, or should it be off the 200 amp main service. Also, it appears that there are some 120V applications associated with the boiler that will require a neutral.

Trying to run wire and need to determine wire size. If I'm running 60 amp circuits, I can get away with #6 and will use #8 for the 30 amp. If I'm running one, 100 amp feed from main service panel, it will be about 102 feet (going under, over, around, up and down, and through). So probably use #1... same as I'm running from 200 amp main panel to the 100 amp sub-panel in garage. Or if I'm coming off the 100 amp sub-panel in garage, probably use the #1 also.

So far, I haven't got a response from the Electro Industries people. Any direction would be appreciated.

 

[WorthFlorida]

I’m not a licensed electrician however you’ll need a breaker larger than 100 amp because at full load it would be near it’s limit. Usually you want the 80% rule. The breaker in the subpanel protects the wiring to the boiler for overload or shorts. The breakers in the boiler protects the boiler. Breaker size is determined by the wire size only and the wire size is determined by the required load.
A local dealer for this boiler probably has an electrician that would know how to meet the local codes.

 

[Sponsor]

 

[Stuff]

As mentioned, heating is a continuous load so need to apply the 80/125% rules if using the 94A rating so wiring needs to support 117.5A and would need to come from main panel in your situation. Feeding the individual 60A breakers should have already figured that in by the manufacturer.

Electro's drawing mentions optional single bus feed kit.

DRAWING SHOWN WITH OPTIONAL SINGLE
FEED BUS APPLIED. MUST ORDER
SEPARATELY BASED ON CB BRAND:
GE BREAKERS: EM-5716 OR EM-5717-GE
SQD BREAKERS: #5701 OR #5702-SD​

 

[Jadnashua]

You may not have enough power to run that thing reliably depending on what other electrical loads you have in the house. You may need to upgrade your service. You certainly cannot run in off of a 100A subpanel, and with 200A max available, assuming that 100A subpanel has much of any load, there's not much left.

Unless you have really cheap electrical rates, NG, if available, is usually a lot less expensive. What did you have in there before?

 

[Dana]

Just curious, but why are you installing a 23kw boiler? That is, what sort of load is it serving? (It's WAY overkill for heating even a fairly large & leaky house in your neighborhood!)