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what is a thermal overload switch?

What is a thermal overload switch? We had a storm and lost power in the house. The fuse did not blow but the next day the pump would not work. We changed the fuse as a precaution. I believe the thermal overload switch tripped but I don't know how to find it.

Posted by avatar on Aug 23, 2009

    • By avatarkellhell1 Aug 23, 2009

    • I am talking about a pool pump. The first thing we checked was the fuse (we do not have breakers in our house) to see if it was blown. The pump is a Proline PE71-III-H 1.5 HP above ground pool pump.

    • By avatarkellhell1 Aug 26, 2009

    • This is for a pool pump. We discovered that there is an external reset switch on our electrical pole for the pool but nothing happens when I try to reset. I took the cover off the pump and made sure there was no debris inside.

    • By avatarSamuel Charles Spriggs May 11, 2010

    • A thermal overload switch opens when its temperature exceeds the specified limit of the thermal switch. These are used in many appliances, practically all motors, etc., etc. -- some trip and can be reset, others have to be replaced. This is different from an overcurrent protection fuse which opens when the current exceeds the specified limit of the fuse. I can't tell from this post what piece of equipment we are working on here. Could you please clarify this: "The fuse did not blow but the next day the pump would not work." What is "the fuse" and "the pump"? thanks... Charlie

Solutions (2)

how to replce thermal fuse on sony tv

A TOC is a bi-metal strip in a canister , they are normally placed on the motor windings and in most cases are auto-resetting.

All they do is sense the temperature of the windings and when they exceed the limit of the TOC (Which is set by the motor maker) they flip the Bi-Metal strip and open circuit the supply.

Normally once the motor has cooled down the strip relaxes back to the original position and the supply is restored.

It is not a standard practice to have a push button re-set however on that will depend on the makers whims

What you may have is a Thermal Fuse which melts if the motor gets too hot and you then need to strip the unit down to both check it and if possible replace it.

By looking at the rating plate on the motor you may find the manufacturer and approach them for a data sheet

  • By Author imageTom Aug 23, 2009

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