Is it common to find too-thin wire in an installation?

[murdock]

I would tend to agree with Andy. Two weeks ago I had a callout to a house. They had 2 pool pump motors on one CB. The one pool pump was fried, and when you start it up, it hums for 9 seconds and the CB trips. Tested the load, and it ran for around 5 seconds at 29Amps. 2.5mm cable, 20 Amp breaker. No damage to the cable whatsoever, no damage to the control wiring (which, if you know these installers was 1mm cabtyre.......no damage).

Also, I am a bit rusty on my regs of head, but the new law does not allow for a cb rating of more than 20 amps on a socket outlet circuit. Anything higher must be dedicated i.e. a welding plug with 4mm cable and a 30amp breaker.....

i take it you know why the pool pump hums like that...the capacitor is normally cooked...it could be a whole lot of things but the majority of callouts i get pool pump will not start...the first thing i ask is does the motor make a humming sound if yes ...i take a cap with.,

[Sparks]

Unless the fan blade is obstructed or the motor siezed up.

[AndyD]

Snails can cause this problem especially in Cape Town. The little critters get in the fan at the back of the motor, they jam it and cause it to burn out or the thermal overload on the motor trips if there is one.

[Jacques#1]

This was theoretically almost a dead short as the resin around the windings melted, just enough not to turn the motor, but enough to lower the resistance so much that the motor turned into a heater .