Main Switch reducing Ze

[Dean Smith]

I don't know if any of you have found this before. During a test today I was finding the Zs on the circuits higher than expected, I tested the loop on both sides of the main switch (new MK dual RCD board) and there was a 0.5 ohms difference!! I have had this before on an RCD and replaced the unit but wouldn't have thought a DP Switch would have this problem. If you have what did you do to rectify?

 

[SirKit Breaker]

Have i read this correctly. you have done a Ze at the switch in the off position as you would, then done the same with it in the on position at the load side, and you have 0.5 ohm difference in your measured results. I can only assume some sort of crap on the switch tips, maybe from manufacture, have you tried operating the switch a few times to see if this improves things, if that doesnt work, then turn something on in the installation, and switch the load, the current across the tips may be enough to clean it, Just an idea.

Cheers..............Howard