Faulty MCB

[rubble2]

Hi,

Helping a friend move in to a new place and we found that the downstairs lights are not working. I checked the consumer unit and the MCB had tripped, I tried resetting it but as I switched it back up there was no mechanical resistance and it just flopped back to the off position. I then noticed that the MCB was loose (lower screw connecting to the bus bar was loose - tightened it up but still no good) I then decided to remove the MCB but someone has butchered the upper screw terminal and I can't unscrew it to disconnect the conductor.

As it was getting late I chopped the conductor off just above the MCB and wired it in to the MCB for the upstairs lights as a temporary fix ( both lighting circuits running off one 10A MCB)

Any suggestions as to how to shift the screw on the faulty MCB? or is it just a matter of brute force? The MCB is a Gewiss B10, are these easily available or will any other fit the CCU.

TIA for any help

 

[Spark123]

Do you need to undo the screw? I'm not sure on Gewiss but usually just undoing the bus bar screw and operating the retaining latch on the MCB base will allow you to remove an MCB.
Can you upload a piccy?
Think City Electrical Factors do the Gewiss MCBs.

 

[Taylortwocities]

If the dolly lever is just flopping around it means that the MCB has suffered a large failure and needs replacing.

 

[rubble2]

Thanks for the info, I will try and track down a replacement MCB

 

[holmslaw]

..

 

[industryspark]

holmslaw wrote

MCB's usually have to be switched to the full off position to reset them after tripping.

Are you talking specifically Gewiss brand here? Not worked with Gewiss mcb's so im not going to comment on them. If your generalising though i beg to differ.

 

[Taylortwocities]

Maybe its those Russian aftermarket contact breakers.?

 

[Click-Sure]

I just thought they made IP rated enclosures, the only product of theirs I've seen?

 

[securespark]

holmslaw wrote

MCB's usually have to be switched to the full off position to reset them after tripping.

Are you talking specifically Gewiss brand here? Not worked with Gewiss mcb's so im not going to comment on them. If your generalising though i beg to differ.

I have used Gewiss CB's, they don't need switching off to switch on again, though the CB after tripping will already be in the off position...

Some RCD's trip to a halfway point (MK, MEM and a couple of others whose names escape me) and then need switching to off before they will reset.

 

[ColJack]

in general, larger MCB's need to be switched off.. but we're talking industrial ones here..

 

[industryspark]

Click Sure wrote

I just thought they made IP rated enclosures, the only product of theirs I've seen?

I think they are more 'diverse' than you would imagine. I always thought they just did enclosures too until i came across some 3 phase sockets and plugs from them which led to me having a peek on their website. Cant remember the site address but i remember thinking they seem to be branching off into a few area's.

Securespark wrote:

Some RCD's trip to a halfway point (MK, MEM and a couple of others whose names escape me) and then need switching to off before they will reset.

I have come across these before yeah, seems to be reasonably common. I fitted some Mennekes 3 phase srcd sockets in one of our workshops a while ago. They have a Doepke (first time id heard of these, German i think) rccb incorporated into them. Remember them as i got a call out at midnight one night from the nightshift, the rccb had tripped to the mid point and they were convinced it had broken as it 'seemed all loose'. My fault i suppose for not educating them when installed!