T

Teddy54

Hi folks , I need to change and MCB in my flat as the rating is to low for the circuit its supplying, Only problem is I have never seen this kind of busbar before. Its goes were the Breaker is sat on top of the busbar just behind the screw/clamp and not actually in the seperate bit at the back on the bottom side.

Now my questions is , am I ok to buy a normal breaker and just cut out the pop outs at either side of the screw and sit the breaker on this way?

Hope this makes sense and any help greatly appreciated.
Cheers
 
Back to get a proper fitting mcb, dont refabricate its housing to suit your install, you have waited this long with it tripping a little bit of time finding a proper fitting breaker

Yes i know, was just a bit of daft thinking earlier on as had never been in the situation before.
 
Teddy This may help in future

electric-power-formula.gif

I have just posted it in the main forum as well
 
Just a note for Teddy54.... Your original Opening Post left out alot of vital info which we had to virtually squeeze out of you.... The change of shower-
The shower rating-
Cable size etc etc would have got you a quicker result and stopped alot of us running round in circles, and as for been a 3rd yr apprentice you should have been able to work out the showers full running current and realised the clamp meter dis-agreed and also been able to cross reference the time/current tables in the regs, this is all recent learning for you.

I can only hope and assume the situation as stated was new to you and you let your nerves overtake your learning which is easily done until you build you confidence in your abililites, try to approach a problem by getting all the info' thats available, calculating the correct load in this case, then use a clamp ammeter to confirm which in this case gave a suspicious result, so judging by the rating of the shower and its agreement to tripping a mcb within 10-15mins as shown in the time/current tables - i could probably guess that you clamp-meter needs calibration but easy to check on known load like 2kw bar fire etc or kettle....
 
1st thing

Find a 50A Wylex MCB (by looking on Google) or local Electrical Dealer

and Try that

MK, Newlec, etc wont fit!

Thats how they make their money! - they keep making you go back to them to get more parts (MCBs in this case) for their Equipment (CU in this Case).
 
1st thing

Find a 50A Wylex MCB (by looking on Google) or local Electrical Dealer

and Try that

MK, Newlec, etc wont fit!

Thats how they make their money! - they keep making you go back to them to get more parts (MCBs in this case) for their Equipment (CU in this Case).



Really 6mm twe 50 amp breaker , installation method ??? if its 100 then the cable is only rated at 34 amps !! the only way to rectify the problem safely would be to increase the cable size to 10mm and install a breaker at 40 amps
 
1st thing

Find a 50A Wylex MCB (by looking on Google) or local Electrical Dealer

and Try that

MK, Newlec, etc wont fit!

Thats how they make their money! - they keep making you go back to them to get more parts (MCBs in this case) for their Equipment (CU in this Case).
Don't be fitting a 50A MCB for 6MM Cable!

And if this MCB is changed, who is doing the EIC for it? I'm pretty sure that would fall under the scope of notifiable work under Part P.
 
It depends where the cable is:
If you clip it directly to the wall (not in conduit) it has a higher A rating - its down to how much heat it can disperse.

Sorry got the wrong size MCB - forgot there was a 40A MCB - woops

Straight from the IEE On site guide:
A 6mm cable can take upto:
34A (if enclosed in conduit in a wall)
38A (if enclosed in conduit on top of plaster)
47A (if clipped onto the wall/in the wall with air circulating it)
51A (on a cable tray)
 
It depends where the cable is:
If you clip it directly to the wall (not in conduit) it has a higher A rating - its down to how much heat it can disperse.

Sorry got the wrong size MCB - forgot there was a 40A MCB - woops

Straight from the IEE On site guide:
A 6mm cable can take upto:
34A (if enclosed in conduit in a wall)
38A (if enclosed in conduit on top of plaster)
47A (if clipped onto the wall/in the wall with air circulating it)
51A (on a cable tray)

So is a 40A mcb what iam after?
 
i suggest that if the OP is to have a go at looking at this probelm himself, then he needs to start with the basics.
What is his load?
what is the install method and derating factors?
Volt drop?
dont ever EVER EVER change an MCB without taking into consideration the design of the whole circuit.
 
I'm amazed by this thread.

Please don't go installing a 40A breaker unless you are 100% sure of the run and installation method of the cable.

Actually, I think that leaving the 32A in place is the way to go, just imagine the size of your electricity bill if the shower doesn't trip the MCB!!!!!!!!!!!!!!!!!!
 
Dont forget your load at 230v is 41.3a before any derating, favourite option uprate the cable size or derate the shower to a suitable rating for your design current and method of installation
 
I find it interesting that all the advice revolves around increasing the breaker size and no mention has been made of testing the circuit integrity or that of the whole installation how long ago was a PIR / EICR carried out this could be a loose connection on the wiring or even in the shower itself

If the supply voltage is extremely low due to a DNO fault then that could be the reason ( yes I have seen that one )

It is all to easy in older installations to just up the MCB size without considering other factors like the shower isolator but I am curious about the OP as a 3rd year apprentice I would have expected a bit more knowledge and why post on here and not discuss it with the spark you are working with
 
I find it interesting that all the advice revolves around increasing the breaker size and no mention has been made of testing the circuit integrity or that of the whole installation how long ago was a PIR / EICR carried out this could be a loose connection on the wiring or even in the shower itself

If the supply voltage is extremely low due to a DNO fault then that could be the reason ( yes I have seen that one )

It is all to easy in older installations to just up the MCB size without considering other factors like the shower isolator but I am curious about the OP as a 3rd year apprentice I would have expected a bit more knowledge and why post on here and not discuss it with the spark you are working with

A reasonable contribution so the only thing I can add is call in a competent electrician
 

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Changing an MCB....
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