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FireMatic fusible link electrical safety switch: this article describes the Firomatic Thermal Switch TS-150 series (or other brand) electrical safety switch that uses a spring-loaded fusible switch to cut off electrical power to a heating appliance (boiler, furnace, water heater) in the event of a fire.
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I don't see any info on the fusible link electrical safety switch. I was wondering why it's required and what is the location normally used? I know they are above the boiler/furnace but are there any specific dimensions above the burner? - G. P. 12/26/2013
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Thanks for asking, G.P.. Fireomatic ™ or Firomatic™ (or its successors and possibly other companies) produced a Firomatic Thermal Switch TS-150 series (or other brand) electrical safety switch that interestingly uses a similar spring-loaded fusible switch to cut off electrical power to a heating appliance (boiler, furnace, water heater) in the event of a fire.
Separately, equivalent devices marketed for the same purpose: turning off electrical power to heating equipment in the event of overheating or possibly fire conditions, are sold using a thermally-operated electrical snap switch in place of the original fusible link mechanical device.
These heat-triggered electrical safety switches are usually installed in a junction box close to the heating appliance or within six feet overhead.
The original Fireomatic™ fusible link electrical safety switch is an electro-mechanical switch that was wired "in series" with power to the oil burner and is required by local fire or electrical codes in some U.S. states. The fusible link melts at (typically) 180-190°F, opening the switch, thus cutting off power to the appliance.
Some sources I found refer to the Fire-o-matic thermal electrical switch as the "New England Safety Switch" as that's where several states required its installation. I've found references to this thermal safety switch for New Hampshire, Pennsylvania, Rhode Island, Massachusetts. Exact installation specifications for the switch location may vary by local state or provincial codes, so you will want to check with your building department.
Other versions of Fireomatic type thermally-triggered electrical power safety switches use a thermally sensitive snap switch to replace the meltable fusible link to open the switch or cut off electrical power in event of a fire or local overheating near the protected heating appliance.
Examples of Installation Specifications for the Firematic thermally-operated electrical safety switch
The Fire-o-Matic thermally operated electrical safety switch is sold mounted in the center of a red-painted rectangular or round steel plate intended to be secured to the top of a rectangular or round electrical box. Other manufacturers may provide similar replacements.
Where to buy a Thermal Cutoff Switch - Sources for fireomatic® type thermal cutoff switches
I'm researching the manufacturer & the switch installation instructions and code citations and will add that information here.
The Fire-o-Matic™ fusible link oil line safety valve or OSV is discussed in detail beginning at
"Above the burner" is not a specification that pertains to that control. That switch is not an electrical switch, it is mechanical, and it controls heating oil flow not electrical power.
Continue reading at OIL LINE SAFETY VALVES, OSVs or select a topic from the More Reading links shown below.
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