Replacing an MCB? Part P?

[leew2]

About a year ago our upstairs lighting circuit tripped out when a bulb blew (it always did, is that common?) but this time would not reset. This was on a 6amp MCB. A few days later an electrician my dad used to know had a quick look at it. He disconnected the circuit in question (working live!) from the MCB which would still not reset which indicated it was a faulty MCB and it would need replacing, he did not have a suitable replacement MCB so as a temporary bodge he simply wired it into the downstairs lighting MCB so that both light circuits were on the same 6-amp MCB. Not really had any issues as most of the bulbs in the house are CFLs but would like to get it sorted.
Will replacing an MCB like for like come under part p? Even if it does, should I just shove part p where it belongs as it is a stealth tax? What are the consequences of doing part p stuff without paying the £130 tax?
Is it OK to pull the service head fuse to do this? My fuse holder has two crimp tags which would need cutting off.

 

[JohnD]

Even if it does, should I just shove part p where it belongs as it is a stealth tax? What are the consequences of doing part p stuff without paying the £130 tax?
Is it OK to pull the service head fuse to do this? My fuse holder has two crimp tags which would need cutting off.

I have a feeling this might be a joke post and you are trying to stir up an argument.

However, if you are serious...


you certainly do not need to pull the main fuse, and you are not permitted to do this. It is also more dangerous than you might think, and sometimes the main fuse holder is damaged or faulty and can be rather unpleasant (any fault here is effectively unfused and can do a lot of damage)

However your consumer unit has a main switch, which cuts power to the MCBs. Depending on age and type of your CU, there might be live parts that are accessible. so post a photo on here for better advice.

If you find it difficult to post a photo, tell us the make of CU, and its colour (this is not a joke) and whether it is metal or plastic, and the part no on one of the MCBs.

There may be a part no or a max load label near the main switch on the outside of the CU.

You should not start doing any electrical work that you do not understand and know how to do and feel justifiably confident with. There will be a few basic tools you need (included insulated screwdrivers which are readily available)

 

[Adam_151]

Will replacing an MCB like for like come under part p?

Yes... *all* domestic electrical work comes under part P, but replacing an MCB for the same type and rating is non-notifiable

Is it OK to pull the service head fuse to do this? My fuse holder has two crimp tags which would need cutting off.

No, its not ok (frowned upon by the DNO, and *possibly* dangerous (depending on the state of the cutout)), and its not neccesary at all, use the main isolator on the board, and bear in mind that the incomming tails will still be live

Ensure that you get an idential MCB (make and range do matter.... DIN rails are standard... busbar placement isn't!), and that its properly tightened onto the busbar

 

[leew2]

My CU:



Lol, just kidding, that CU was removed about 14 years ago, It was still in use though upto about 1994. When we moved into the house it was almost unaltered from when it was built in 1934, I assume the CU dated from then although the meter and the service head both looked alot newer. There were a few round pin sockets and a total of about 6 single square pin sockets in the entire house.
After about 1 year of messing around with 4 plug strips and extension leads the house was fully re-wired (by a "professional"), this CU was fitted:



The MCBs fitted are as follows:
80A/30ma RCD main switch
32a ring main for kitchen
32a ring main for downstairs
32a ring main for upstairs
the red MCB is for the heating, unknown rating (has nothing written on it)
6a downstairs lighting (in down position, broken, needs replacing)
6a upstairs lighting (with downstairs also wired into it)
32a for oven
40a for shower

The oven and shower MCBs were added at a later date which explains why they are at the wrong end of the CU.

The small CU above the main one contains a 40a/30ma RCBO for the garage (where there is another CU). It was added later as whoever rewired the house put the socket and light in the garage on the ring main until we had it re-done properly. Not sure how it is connected to the main CU.
The timer thing to the right is for underfloor heating (which is fed from a fused spur on downstairs ring main)

The CU has a label on it stating to isolate the supply before removing the cover, however I cannot see any way of doing this other than at the service head fuse.
After scouting around the web though it seems like the DNO would be able to install an isolator switch between the meter and the CU. Any idea of the cost of this?


Another related question I would like to ask is I want to convert the 16a radial socket circuit in my garage to a ring main by replacing the 16a MCB with a 32a MCB and running a 2.5mm T+E cable from the last socket back to the CU so I can use my welder and a heater at the same time (at the moment I have to turn off the heater, then weld then turn the heater back on which is inconvenient, if I forget to turn the heater off then it trips and the garage CU is awkward to get to due to junk in front of it). Would doing this require payment of the £130 part-p "tax"?

Thanks again

 

[Spark123]

What exactly does it say on the front of the suspect MCB?
If you look very carefully at the end of the lever the size should be written on them too.
That board uses Square D QOE MCBs, just need to get the size and type correct.
Having one RCD protecting all circuits is now frowned upon.
To isolate the CU you need to turn the RCD to the left hand side off. Be very carefull of the meter tails as these will still be live.
As for q2, yes it will be notifiable.

 

[Chri5]

I disagree, it's mtce work, swapping like for like, so Part P doesn't apply.

(flame suit at the ready)

 

[Spark123]

Read the last paragraph in the OPs last post again