Temperamental Water Heater Switch

[Jupiter01]

I was replacing a electric hand water heater today. This has the following isolation switch, which is powered by a 32 Amp Breaker.

I switched the above on and off and verified power at the heater using my two pole tester. Once I was satisfied that this was the correct isolation point, I switched it off.

Before I could start working on replacing the heater, I noticed that the light on this switch was intermittently lighting up whilst the switch was in the off position. Here's a picture of it:

When this was the case, there was power at the heater - despite the switch being in the off position. Given that I spotted this, I switched off the breaker before doing the work.

I did then open up the switch and all the supply and load cables look good as do the lights for the indicator.

Q. Can you please shed some light on what may be causing this?
Also, would it have been reasonable to start working on replacing the heater after isolating it at this switch (after testing with the 2 Pole tester) or is this bad practice?

 

[terryplumb]

You said there was power at the heater when isolation switch was off ,what was the voltage present ?,of course it wouldn't be safe to work on the heater if it's still powered up.
The switch would appear to be faulty.

 

[JohnD]

in your lower pic the tumbler of the switch appears to be in an intermediate position

I surmise it is worn out and belongs in the bin.

 

[Jupiter01]

when isolation switch was off ,what was the voltage present ?

Around 110volts

of course it wouldn't be safe to work on the heater if it's still powered up.

I was trying to understand whether under normal circumstances it would be reasonable to continue work once I had taken the steps that I did to identify the isolation switch. Or should you always switch off the relevant breaker?
What’s deemed as normal and good practice?

 

[terryplumb]

Normal practice would be to establish that the switch is a double pole isolation switch . After turning it off then test that whatever it connects to is dead ,with an appropriate test instrument ,that has already been proved to be working properly ( the test instrument itself that is).

 

[Jupiter01]

Normal practice would be to establish that the switch is a double pole isolation switch . After turning it off then test that whatever it connects to is dead ,with an appropriate test instrument ,that has already been proved to be working properly ( the test instrument itself that is).

Admittedly, I didn’t test my equipment on this occasion but if I followed the above, I would have encountered an electric shock given the temperamental issue with this switch. Is this one of those freak unavoidable situations?

 

[terryplumb]

How so ,you would have found the appliance to be live after turning the isolation switch off ?

 

[Jupiter01]

No. It was not passing power through at all times when in the off position. When I first tested in the off position, there was no power. I then noticed the dim light in this switch and the presence of power. This was intermittent.

 

[terryplumb]

Ah ,gotcha. Then you should have been alerted to the switches rocker not making a positive clicking on/ off , which it would almost certainly not do.

 

[conny]

And yes, the correct procedure is to ALWAYS isolate, preferably at the consumer unit for added safety, than simply relying on a local switch.

 

[JohnD]

I would have encountered an electric shock given the temperamental issue with this switch. Is this one of those freak unavoidable situations?

No.

 

[Jupiter01]

No

You need to give me more than that John...

 

[conny]

It's not unavoidable. You avoid it by isolating at the consumer unit. If in any doubt about isolating at a local isolator, such as a switch, then always isolate at the incoming supply. I.E. the consumer unit.

 

[Jupiter01]

I guess my confusion stems from the fact that all my testing suggested that I had an isolation switch where I can safely isolate, but then noticed the intermittent switch issue. Perhaps the feel of the switch should have raised an alarm bell...

 

[Taylortwocities]

The fact that you measured

Around 110volts

Should have sounded that warning bell!