MK MCB Replacement

[butcherboy70]

Sorry to sound so naieve but this is cracking me up!
I simply want to replace a 32A for a 40A, the trouble is that I cannot get the old one out, am I missing a trick somewhere?

I have isolated it, removed the live, unscrewed it from the busbar and pulled down the retaining catch underneath it!

Please help someone

 

[ricicle]

Can I ask why you want to change a 32A mcb for a 40A one?

 

[butcherboy70]

I was told by an electrician that was why my shower was tripping after about 4 mins use, I get longer in the winter!

 

[ricicle]

Did he tell you anything else?

 

[butcherboy70]

Nothing!, just plain and simple. "That is definately your problem"

To be honest I was convinced that I had put too bigger shower unit in, a Gainsborough 10.5 SCL to the existing cable.
It was all wired up and fused but without the unit installed when I moved in, I assumed it was a simple case of putting the shower in and connecting the live to the existing 32A MCB!

 

[ricicle]

Did he mention that you can't just go uprating your circuit protection without first checking certain factors concerning the cable to the shower based upon its current carrying capacity, it's length and how it is installed!

 

[RF Lighting]

Before anyone will tell you how to do it, first of all we need to know for certain that the cable you have is big enough to carry 40A.


Most showers, until recently were wired in 6.0mm², which is not big enough to carry 40A.

If you were to simply uprade the MCB and carry on using the shower with an undersized cable there is a risk of the cable over heating, which will end up causing you big problems.

You also need to ensure that you shower isolator switch is rated to at least 45A, as some will only be 32A which will also be damaged by the increased load of you new shower.

 

[butcherboy70]

Sorry Ricicle, he asked me some questions, was it 6mm cable and what was the distance from the RCU to the shower.

Upon checking, it is 10mm cable up to the loft, that is where I fed it down to the airing cupboard and put in a pull switch, 10mm out from there to the unit

 

[DESL]

There's a possibility that the 32A MCB got a bit hot and has distorted or even melted at the bottom where it connects to busbar, that's why you are having difficulty removing it. They can swell a bit and get stuck to adjacent MCBs best get it checked out and the adjacent MCB/RCD as I have seen it happen in MK boards

 

[butcherboy70]

Many thanks for all answers to this post, I guess my best bet is to get a regestered sparkie along to check it all out and for me to just concentrate on cutting meat, lol

Anyone know of a good electrician in the Scarborough area?

 

[RF Lighting]

It isn't just being held in place by the din rail clip is it?

Once you have removed the busbar you will see the din rail clip (loacted here)

Normally this clip will be up to hold the device onto the din rail

You need to insert a screwdriver into the hole and gently lever the clip downwards while pulling the bottom outwards.

 

[butcherboy70]

RF Lighting, do you think that it will solve my problems if I just try to do that? I tried before and it still would not come out!

 

[Steve]

RF, would you have to remove the busbar first? Or is there enough give in the terminals?

 

[RF Lighting]

If you undo the bottom screw fully there is enough play to remove the device without removing the busbar, but it is a bit arkward.


It is much easier to do (and see the din rail clip) with the busbar removed.

Also if the busbar is removed you can move the rest of the devices to the right a bit to make removing the device you are replacing a bit easier

 

[butcherboy70]

So RF, by what I have read, if I remove the busbar and replace with a 40A it will cure my tripping problems?