Fireomatic fusible link electrical safety switch for heating requipment (C) InspectApediaFirematic Thermally-fused Electrical Switch
What is the New England Safety Switch used to shut off electrical power in the event of a fire, who makes it, how is it used, where is it installed?

  • FIREMATIC FUSIBLE ELECTRICAL SWITCH - CONTENTS: explanation of the Firematic fusible link electrical power shut-off switch used to turn off electrical power to heating equipment in the event of a fire. What is the "New England Safety Switch", where and why is it installed, who requires it, and who makes it? How does this fusible link power switch work?
  • POST a QUESTION or READ FAQs about fusible link electrical power switches for heating equipment safety control

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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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How & Where do We Install a Fusible-Link Firematic™ type Thermally-Fused Electrical Safety Switch

Fireomatic fusible link electrical safety switch for heating requipment (C) InspectApediaReader Question: where to install the fusible link firomatic thermal switch on heating equipment

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

(e) An electrical thermal switch fused to break the ungrounded conductor in the main circuit at 165°F, shall be installed in the main power line within six feet over the top of the burner-boiler or burner-furnace.

If the ceiling above the burner-boiler or burner-furnace exceeds 12 feet in height, an additional thermal switch shall be installed on the ceiling and connected in series with the lower switch.
- Massachusetts building code:

Oil or gas burners both with fireomatic switches, service switches and emergency switches properly marked and in correct locations. (check with Fire Department if you have any questions at (603) 635-2703); - New Hampshire reference: - quoting:

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

  • Start at your local heating equipment supplier. Most HVAC and plumbing supply businesses have or can obtain a fusible link thermal switch, aka the "New England Safety Switch" or a Firematic® Thermal Switch. If you need to contact the manufacturer or supplier for these devices we list those companies just below.
  • R.W. Beckett (produces fusible link oil line safety valves, check valves, and thermal switches. - Website:
    Two thermal switches are listed by Beckett:
    • Part # 12527, U.L. Switch for 3/4" and 4" round junction box Firomatic # 91301150
    • Part # 12501, U.L. Switch for 4" square junction box, Firomatic # 91301300
    • Beckett Corporation describes their thermal switch as follows:

      Thermal switches - a safety device which provides added protection to fuel burner installations. it is a thermally operated switch installed in the electrical power line to the burner. It is normally set at 165 degrees F and remoes power if the ambient temperature reaches this point.

      The burner then shuts off immediately. The thermal switch is usually positioned on the ceiling, close to the burner. It SHOULD NOT be used manually to start an stop the burner motor. When properly installed, there are no exposed electrical wires or contacts, before or after firing - this is important.

      The fusible element is the handwheel of the switch - after it "fires" simply replace the handwheel to restore the switch. Contact ratings are: Pilot 120V, 60 Hz, 360VA, 1/2 horepower, 12volts, 60 Hz.

  • Sid Harvey
  • Possible: Olson Manufacturing S95010A Square Fireomatic,, Toll Free: 1.800.255.0074, Email: - sold by heating equipment suppliers and online from various sources including at and
  • Asco Products (Emerson Industrial)
  • R.W. Beckett (U.S. & Canada) Firomatic Fire Safety Valves
  • ISP Automation (Firematic)
  • Webster Fuel Pumps & Valves, a vacuum-activated OSV
  • A confusing link that Google searches return but that won't help you with this topic is at is a fire equipment & truck company

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
at OIL LINE SAFETY VALVES, OSVs - this is a fusible link safety valve on the heating oil supply line; its location is dictated by the physical location of the oil piping, filter, tank, and oil burner.

"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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