Romex on a Boiler?

I inspected a house with a natural gas fired hot water boiler today. The main electric supply to the boiler was white NM type Romex cable to the service switch on the side of the boiler. The Romex then continued on to the control box on the boiler. The cable from the control box to the circulator pump was BX type armored cable.

I’ve never seen anything but BX or EMT tubing on a boiler before. It looked like a home owner modification.

Is there an issue with using Romex type cable on a boiler due to the heat thrown off by the boiler?

Sorry but I didn’t get a picture.

Thanks in advance.

I would like to know this answer too. I have only seen bx.

I do know that the installation of a boiler here in MI requires a LC mechanical or the inspector will not even look at it weather it’s done correct or not.

non-metalic sheathed cable must be fastened to the builing surface or boared holes in framing members, and can be be installed along running boards. No hangy-dangy, no tie-wraped to the gas line, etc.

ps- Heat isn’t so much the issue. Its physical protection.

**[FONT=Arial]Here’s a piece from the handbook.

IMO I would call the use of romex a defect in the area you described.


[/FONT]**The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
The definition of the term *ampacity *states that the maximum current a conductor carries
continuously varies with the conditions of use as well as with the temperature rating of the conductor insulation.

For example, ambient temperature is a condition of use.

A conductor with insulation rated at 60°C and installed near a furnace where the ambient temperature is continuously maintained at 60°C has no current-carrying capacity.

Any current flowing through the conductor will raise its temperature above the 60°C insulation rating.

Therefore, the ampacity of this conductor, regardless of its size, is zero.

See the ampacity correction factors for temperature at the bottom of Table 310.16 through Table 310.20, or see Annex B.

The temperature limitations on conductors is further explained and examples given in 310.10 and in the commentary following that section.


310.10 Temperature Limitation of Conductors


[FONT=Arial]No conductor shall be used in such a manner that its operating temperature exceeds that designated for the type of insulated conductor involved. In no case shall conductors be associated together in such a way, with respect to type of circuit, the wiring method employed, or the number of conductors, that the limiting temperature of any conductor is exceeded.


Joe- would you accept romex dropping into a length of EMT or greenfield that is fatened to the boiler housing? This is quite common in my area and I’ve always allowed it with my focus on physical protection. I had not given much thought to the heat issue beyond common sense.


NM cable is of the older type, and in 1984 the NM-B was introduced. The NM is with 60 degree C insulation, and the NM-B is with 90 degree C insulation but still must not be loaded at more that the 60 degree C column.

I think that the sleeve you mention is OK and is permitted, but would worry about the condition of the insulation.

Are there any signs of deterioration?

Thanks for your help. Unfortunately I can’t say if the cable was NM or NM-B. I was unaware of the difference. I do believe that it was recently installed as the tenant (this was an old 4 family) stated that the board of health recently made the landlord rewire the boiler as it was wired to a different tenants meter.

I will recommend evaluation by a licensed electrician based on the proximity to the furnace.

Thanks again.