Because it would provide no overcurrent protection for the cable.
We await your photos with interest. What make is the CU? Is the 100A breaker a Type B?
ground floor power sockets routed off Upstairs ring...
- Thread starter mbga9pgf
- Start date
Sponsored Links
100A MCB? Photos or it didn't happen
I'm willing to bet 50p it's a 100A rated switch.
Sponsored Links
Hi all, got the photos.
Here is the main CU. The incoming supply is rated at only 80A and the meter is registered as being able to handle 80A. Incoming supply is switched using an 80A 100ma protected RCD. Fine.
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2717.jpg
RH side of the CU:
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2719.jpg
63A RCD protected at 30ma. Now, my issue is this. The main annex protection comes OFF the 63A side of the CU and not the 80A side. The annex has an electric power shower (about 7Kw) and wiring for the electric cooker. Not enough I reckon, as the Annex MCB is protected at 40A. With spots, cooker and shower on, its going to trip the CB.
Inside the annex, we have this:
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2727.jpg
40A supply protected by a 100a switch?!?! The CU is made my MK.
Thoughts? If I were to replace 7Kw power shower with a hot water mixer supplied unit instead and wired in the kitchen cooker power supply correctly, I cannot see the power supply being an issue. Personally, I would like to see a second supply or the current main house CU supply upped to 100a or above, at the same time they install the economy 7 meter...
The SWA I talked about previously trailing across the garden is photo'ed here
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2721.jpg
Not great and something I intend to sort. If I were going to up the supply to the annex, to say a 60A MCB using ducted 16mm wire, I have worked out that would be plenty for "worst case" expected usage, accounting for 3% voltage drop max across the wire length, wire raing etc Plus, neat tidy and no training wires across the borders.
Other issue:
Kitchen 2 way lighting wired incorrectly and only 2 core between the switches for the wiring. Is there an easy way of pulling out the 2 core and replacing with suitable 3 core to enable 2 way lighting without having to open up the wall cavity.
Does the main power supply to the light switch usually include an earth? at the mo, one switch at one end has the live, the other the neutral and the earth is simply attached from the switch to the switch housing rather than being connected to any earth wire....
Here is the main CU. The incoming supply is rated at only 80A and the meter is registered as being able to handle 80A. Incoming supply is switched using an 80A 100ma protected RCD. Fine.
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2717.jpg
RH side of the CU:
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2719.jpg
63A RCD protected at 30ma. Now, my issue is this. The main annex protection comes OFF the 63A side of the CU and not the 80A side. The annex has an electric power shower (about 7Kw) and wiring for the electric cooker. Not enough I reckon, as the Annex MCB is protected at 40A. With spots, cooker and shower on, its going to trip the CB.
Inside the annex, we have this:
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2727.jpg
40A supply protected by a 100a switch?!?! The CU is made my MK.
Thoughts? If I were to replace 7Kw power shower with a hot water mixer supplied unit instead and wired in the kitchen cooker power supply correctly, I cannot see the power supply being an issue. Personally, I would like to see a second supply or the current main house CU supply upped to 100a or above, at the same time they install the economy 7 meter...
The SWA I talked about previously trailing across the garden is photo'ed here
http://i979.photobucket.com/albums/ae271/mbga9pgf/IMG_2721.jpg
Not great and something I intend to sort. If I were going to up the supply to the annex, to say a 60A MCB using ducted 16mm wire, I have worked out that would be plenty for "worst case" expected usage, accounting for 3% voltage drop max across the wire length, wire raing etc Plus, neat tidy and no training wires across the borders.
Other issue:
Kitchen 2 way lighting wired incorrectly and only 2 core between the switches for the wiring. Is there an easy way of pulling out the 2 core and replacing with suitable 3 core to enable 2 way lighting without having to open up the wall cavity.
Does the main power supply to the light switch usually include an earth? at the mo, one switch at one end has the live, the other the neutral and the earth is simply attached from the switch to the switch housing rather than being connected to any earth wire....
Now, you'll have to forgive me but I am pretty lazy. I'm happy to help but I can't be bothered to go and fetch your photos off photobucket.
So I suggest you go to photobucket and click on each image. at the bottom there will be a box called
SHARE THIS IMAGE.
Copy the the IMG CODE
then go to your post above, hit the EDIT button and PASTE the IMG CODE into your post .
Then the pics will be there to see along with your descriptive text.
I'll bet you get more help that way...
or
don't use photobucket but follow the DIYNOT Images facility.
So I suggest you go to photobucket and click on each image. at the bottom there will be a box called
SHARE THIS IMAGE.
Copy the the IMG CODE
then go to your post above, hit the EDIT button and PASTE the IMG CODE into your post .
Then the pics will be there to see along with your descriptive text.
I'll bet you get more help that way...
or
don't use photobucket but follow the DIYNOT Images facility.
Not really - any new circuits or extensions to existing ones will require that RCD to be a 30mA non time-delayed one which means you can't keep the existing split-load CU, unless you replace the incomer with a switch and replace the MCBs with RCBOs.
Makes no difference, as it's on a 40A MCB, but it needs to be on the 63A side as that's the one with the 30mA RCD.
Probably won't.
So the shower is on a B50 downstream of a B40.Inside the annex, we have this:
No, the protection for the supply to the annexe is the B40 in the house CU.
That 100A switch is just that, just a switch, it provides no protection to anything - as more than one person has already surmised, it's not an MCB. 100A is just what it's rated to carry.
1) I think your electrics have been fiddled with by an idiot.
2) I think you're out of your depth.
3) I think you should get an electrician.
Hi all,
Wanted to thank you for responding to this thread. I finally managed to connect and test the last replaced circuit on my property this week (connecting 2 sides of the smoke detection system up).
Whilst I may not have appreciated the suggestions of "getting someone else in to do it" at the time, it made me go away for 6 months and thoroughly read through the 17th edition and on site guide, not to mention how to carry out safe isolation and testing procedures before I touched on any major wiring projects.
Whilst I know some of you will have issue with carrying out cable installation etc, I can hand on heart say after getting the bulk of the wiring inspected by a qualified spark that we now have a fully safe install.
Unfortunately, after ripping up my floorboards, I ended up doing pretty much a complete rewire.... What I found was pretty disgraceful and I was fortunate to have discovered the scale of the problem whilst tackling a separate problem.
Anyways, thanks for pointing out that I didn't know my @rse from my elbow, it made me re appraise and do a lot more reading especially into the testing side before i cracked on. didnt manage to get a single shock so it mus have worked! I ended up installing a completely new submain separate completely from the CU, initially protected to 100mA, then 30mA at its consumer unit. I replaced the existing cu with a new split board, one side to 30mA and the other using RCBOs.
To give you an idea, total Materials costs came to over 1700 quid as its quite a big house and took me pretty much 2 months solid to do. Whilst i would have loved to pay a spark, unfortunately the finances simply dont allow it.Wago boxes saved me loads of time, although I preferred crimping once i was confident I could do it properly.
Anyone know the best place to sell my mft as I no longer need it and don't really fancy paying to keep it calibrated if I am not using it any more?
Wanted to thank you for responding to this thread. I finally managed to connect and test the last replaced circuit on my property this week (connecting 2 sides of the smoke detection system up).
Whilst I may not have appreciated the suggestions of "getting someone else in to do it" at the time, it made me go away for 6 months and thoroughly read through the 17th edition and on site guide, not to mention how to carry out safe isolation and testing procedures before I touched on any major wiring projects.
Whilst I know some of you will have issue with carrying out cable installation etc, I can hand on heart say after getting the bulk of the wiring inspected by a qualified spark that we now have a fully safe install.
Unfortunately, after ripping up my floorboards, I ended up doing pretty much a complete rewire.... What I found was pretty disgraceful and I was fortunate to have discovered the scale of the problem whilst tackling a separate problem.
Anyways, thanks for pointing out that I didn't know my @rse from my elbow, it made me re appraise and do a lot more reading especially into the testing side before i cracked on. didnt manage to get a single shock so it mus have worked! I ended up installing a completely new submain separate completely from the CU, initially protected to 100mA, then 30mA at its consumer unit. I replaced the existing cu with a new split board, one side to 30mA and the other using RCBOs.
To give you an idea, total Materials costs came to over 1700 quid as its quite a big house and took me pretty much 2 months solid to do. Whilst i would have loved to pay a spark, unfortunately the finances simply dont allow it.Wago boxes saved me loads of time, although I preferred crimping once i was confident I could do it properly.
Anyone know the best place to sell my mft as I no longer need it and don't really fancy paying to keep it calibrated if I am not using it any more?
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
