Velly Interlesting... MCB Behavior

Jun 06, 2020 Last reply: 6 years ago 6 Replies
C

Hi All



I have a relatively modern Wylex CU Which has (amongst other stuff) 6 MCBs protected by an RCD.



I was checking out the topology of one of the circuits today (It has 2x 2.5mm T&E at the CU, but most of the sockets only have 1 T&E, so I wanted to check whether it was a ring, or two radials (or a broken ring) wired into the one MCB (I found if I connected either leg then all the sockets were live, so it APPEARS it is some sort of ring (perhaps with JBs below the floor and a short T&E up to each socket).



Anyways onto what I found to be unusual behaviour....



Whenever I switched this MCB off or on the Power on the adjacent MCB appeared to be interrupted for a very short period (1/10 second??). And then it would resume as if nothing happened.



Any ideas if this is to be expected and/or why it might happen?



TIA



Chris


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J

If it does it for both off and on, then it sounds like a lose connection on an adjacent MCB (possibly to the circuit or the bus bar) such that its losing contact with the physical shock from switching the nearby MCB...

Have you checked all terminals for tightness?

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C

Hi John,

I?ve not checked connections. I was thinking this was something ?clever?.

I should have though KISS!

I will have a look.

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A

And that the bus bar is "inside" the MCB clamp.

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A

formatting link
was one I found at work.

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T

Check your nuts. You could have a screw loose.

NT

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C

Someone wrote

?Check your nuts, you could have a screw loose?

Funny you should mention that, I had an i Ultrasound today, and my testicular pain is apparently due to varicose veins. I blame blue balls caused by uncooperative girlfriends back in the 70s!

Anyway, for carious reasons I?ve not managed to get the covers off the CU again yet.

But I?ve decided that what was happening with the TV probably wasn?t interruption of the mains supply, but rather a glitch on the aerial signal causing the screen to blank for a moment.

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