Here in Central New England we have recently experienced a catastrophic ice storm, certainly the worst in my memory. As a result power to most of the area was lost for a few days and up to two weeks. We were among many others out “bumping” heating systems with generators to keep homes and businesses from freezing pipes. In the process the subject of wiring issues again became very apparent.

 As a serviceman you are working in a strange building with no power (obviously) and not able to switch breakers to determine their validity. To safely hook up a generator you MUST find both the power AND ground wires, remove them ideally from the power panel and attach them to the generator. Consequently you must manually trace and verify each wire to the system for integrity and purpose under very poor working conditions, a daunting and dangerous task!

By law a power heating appliance must be isolated with its own, dedicated circuit breaker and clearly marked in the power panel. As a practice in new installations we personally always place the heating system breaker in the lower left or right corners of the panel and clearly, permanently marked. After all, what is potentially the most important breaker you would want to get to in a hurry?

Singularly from experience the most common and the first violation we look for is wall and kick space (commonly called “toe”) heaters. It is just too easy and convenient to wire them to the nearest room receptacle than run wiring back to furnace safety wiring. So you get a service call for an ailing heater and unknowingly begin working on a “hot” appliance or discovering you can’t find where or what circuit it is wired to. Exciting.

More disturbing however is the occurrence of separate breakers for boilers and circulators in hot water heating systems. In the process of jumping boiler wiring you discover it won’t start, or if it does the circulators and thermostats don’t work. These functions are inter-wired logically in the system and can present surprises to your serviceman when not powered simultaneously. They must be commonly wired to a single or “ganged” breakers in the panel.

There are several ways of doing this, but please consult with your electrician for wiring practice and Code Compliance in your particular jurisdiction:

  1. Wire both circuits to the boiler breaker, total load, wire and breaker size permitting. Note that most central heating system appliances use 14 ga. service wiring and thus use a 15 amp breaker ONLY. If the combined load exceeds the breaker capacity DO NOT INCREASE BREAKER SIZE under any circumstances. Instead go to the next option(s).
  2. Consider using a 15 Amp. Two-Pole Breaker (220V) and instead wire the boiler to one 110V leg (side) connection and the circulators to the other. Unless you have many large, older circulators this should be adequate. Again, refer to your local electrician for Code Compliance.
  3. If there is a larger than 15 amp demand on either circuit you will have to “gang” breakers, that is, placing them next to each other in the panel and mechanically coupling their actuators with a kit accessory, available for most breaker types at an electrical trade shop.

Then in any above case, clearly label the breaker and its functions in your electrical panel.

Oh yes, if none of this applies to your circumstance at the least switch your breaker to verify it cuts power to your heating appliance. One home had been rewired without changing identities. The correct breaker was three up on the right. Find that in the dark with no power.

Your Serviceman & I thank you!