DIY Doctor

suspected mcb fault but unsure....

Postby SiLights » Wed Aug 08, 2012 8:27 pm

hello kind people, I have a problem with my electrics in the kitchen and am unsure how to proceed.

cause = me overloading the circuit by having the microwave, fridge, aircon all running and attempting to switch on the vacuum as well. Power sank to about 20% on all these things, so I switched off immediately the vaccum and microwave.

The MCB did not trip, infact everything seemed fine until I restarted the microwave and it carried on running at very reduced power so I switched it off aswell.

I then noticed that the fridge was also running extremely low, so i had to switch that off aswell to avoid damaging it.

I have now connected the fridge to a different circuit from the next room and it works fine.

It feels like a phase or even two are missing, the hob and oven are beeping warnings at me and anything connected to that circuit is sounding sick so I've unplugged the lot.

MCB switches all on, master on and RCD's on, have checked all the fuses (a 16A for each phase) and they are fine also.

I'm now at a complete loss as to what to do it possible for an MCB to appear as though working ok (ie switch on) but not passing supply correctly ?

any ideas gratefully received :)

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Simply Build It

Postby ericmark » Sun Aug 12, 2012 4:44 pm

It is very rare to have a domestic three phase supply in the UK. So first question where are you and what makes you think it's three phase.

Some countries like Algeria did have split and three phase supplies so I am being careful in case your not in UK.

If in UK then something must have been damaged and really the chances of finding it with a forum are slim. Time to call an electrician.
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