Mike the Poolman


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Burnt Relay from Pool Controller

April 22, 2017

Photos of burnt relay

A few weeks ago I got a call to troubleshoot a pump that wasn’t working. I opened up the swimming pool controller and found this burnt relay. I thought people would like to see what it looked like and how much it melted. I’m not sure if this one came out of a Jandy or Pentair pool controller because both companies use similar relays. 
Burnt relay in pool controllerBurnt relay in pool controller-2

Jandy uses this relay for their RS units (older Jandy Ji controllers use “relay boards” but I rarely come across them anymore).

Pentair uses this relay for their Easy Touch, Intellitouch, Sun Touch and Soar Touch controllers. Compool (now owned by Pentair) controllers use a different type of relay.

Why did this relay burn?

The most common cause of a burnt relay is a loose connection (“loose wires cause fires…”) where the wire attaches to the relay. When the connection is loose it can arc and generates a tremendous amount of heat which melts the plastic, burns the wire, burns the relay and hopefully, trips the breaker to prevent a fire. If the breaker is sized properly it should trip and cut power to the circuit to prevent further damage (the house burning down). When a relay melts it almost always has gone bad and failed to work.

A burnt relay is usually preventable

Most relays I’ve seen burned and melted were preventable and originated from one of two things:
a) the person who wired it didn’t screw the terminal down tight enough to prevent arcing. Always double check connections to be certain they are snug and secure!
b) the person who wired it used stranded wire. Solid copper wire is preferred on relay connections because it doesn’t change size. While the gauge of stranded wire doesn’t change, the mechanical size of the connection can change. When (untwisted) stranded wire is tightened down it pushes out and changes shape, thus decreasing the thickness of the wire and the potential connection to the terminal.

Have I connected stranded wire to relays? Absolutely. However, I ALWAYS make sure that stranded wire is twisted clockwise and whenever possible I insert it on the LEFT side of the screw terminal. Twisting the wire clockwise bunches it together and inserting on the left allows it to tighten clockwise and thus gives one a better chance for a good connection. 


In conclusion,
make sure connections are tight !!

Mike the Poolman


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