Adding to a full Consumer unit

[Steve Hart]

I want to install an electric shower. I've read all the previous postings and have got the cable and MCB size sorted out but my consumer unit is full. The current arrangment in my house is that the meter tails are connected to 2 small square junction boxes and from there wired to the CU. Inside the junction boxes is a metal terminal block with 3 slots two of which are occupied by the tails from the meter and out to the CU. My question is - if I install a separate isolator switch for the shower is it safe for me to supply that from the spare slot in the 2 junction boxes or am I at risk of overloading the junction boxes?
Can anyone advise please?
Cheers
Steve.

 

[D J Fryer]

There's a good post in this thread //www.diynot.com/forums/viewtopic.php?t=7553 by Plugwash about adding a shower CU to your mains CU if this is of any help?

 

[breezer]

no there isnt, plugwash suggests pulling the main fuse which is dangerous

 

[plugwash]

seems like you already have henly blocks in place

a shower CU (which consists of a rcd incomer and a mcb for overcurrent protection) can be connected to theese useing 25mm tails

the problem is isolation
most sparkys would just pull out the service fuse this shouldn't be too dangerous but there are a couple of things to watch for
1: turn off the main switch on your CU *before* pulling the service fuse to remove the risk of arcing
2: be very carefull not to put your fingers in the space that opens up as you pull out the fuse as on some older holders pulling the fuse will leave exposed live parts

 

[breezer]

i should also point out that to do the above is ileagle, it is consdered to be tampering with the supply company equipment. but then you can always name who told you to do it

 

[D J Fryer]

no there isnt, plugwash suggests pulling the main fuse which is dangerous

Apologies - if something is in a for reference thread (especially one that has been 'stickified') should the moderators not ensure it is generally accepted as sound advice?

Lets face it - it will be the first thread checked when visiting here for the first time and I imagine a lot of queries are referred to that thread by the well established members to save repetition.

 

[breezer]

i like your thinking, but it doesnt work like that. most people we have to refer to the "for reference" section.

this is a diy forum what you do is entirly up to you, we can only give opinions, mine is plugwash' advice is dangerours regarding consumers units (but i am not the only one who thinks that)

perhaps the mods do need a call

 

[plugwash]

most sparkys i have spoken to say they do it

some have even been explicitly told to by the rec before

really unless the rec sees something dodgy they aren't going to worry about missing service fuse seals

if the rec actually provided an official means of isolation for the customer then there would be no need for any of this sadly they don't

i personally think they should make a single unit with a fuseholder a meter and an isolator in one unit and the output terminals under a totally seperate cover from everything else

btw our service fuse and meter tails have hqad no seals for a couple of years and the rec haven't noticed

 

[breezer]

i understand what you are saying, but electricains will test with apropriate test gear before connecting back, the average diy person can / will not test

also only after being prompted did you mention there are still live LETHAL parts exposed, electricains do not mention it because we already know.

as my late father used to say "a little knowlede is a dangerous thing"

yes electrcians will tell you "yer mate pull the fuse, it can only go bang"

what they dont tell you is:

they will test it before reconnection

there are LIVE parts exposed

they use insulated tools

they know what NOT to touch

if it does "go bang" it can be fatal

they will deny they told you any thing

being an electrican takes skill as well as knowledge, following a few words / instructions does not mean it is right / you are safe

 

[securespark]

Breezer is right. It's one thing being "told" to do it by a REC if you are a FQ spark, quite another if you are DIY.

Please follow the advice hereafter: Basically, get yourself an isolator fitted, then you can isolate your CU and its tails, and you will know you are safe & legal.

QUOTE:

If you need to add a consumer unit, or change the existing one, the best course of action would be to call the Regional Electricity Company (REC), and ask them to fit (or install one yourself and ask them to wire in) an isolator that is fitted inbetween the tails from the meter and the CU itself. This means that the tails to your CU are also isolated, thus making the CU safe to work on. If you want to, you can always fit a henley block inbetween the new isolator switch and the CU, allowing you to fit extra CU's in the future.

BUT PLEASE DON'T:

Tamper with the cut-out seal or cut out

Tamper with meter seal or tails

as this will render you liable to prosecution, and may even be lethal. One slip is all it takes - I'm not trying to scare anyone, but I've seen it done, and it's not pretty.

Leave the meter seals, cut out etc to the REC, and once you have installed your isolator, you can work on the system in complete safety without bothering the REC again.



================A================B=============C================D==============EEE


=: cable
A: cutout
B: meter
C: isolator
D: Optional Henley Block
E: CU or CU's.

 

[ban-all-sheds]

If you need to add a consumer unit, or change the existing one, the best course of action would be to call the Regional Electricity Company (REC), and ask them to fit (or install one yourself and ask them to wire in) an isolator that is fitted inbetween the tails from the meter and the CU itself.

I asked Southern Electric to do this the other day.

They said that they don't do it.

 

[securespark]

No, some REC's don't - mine doesn't, but there's nothing to stop you fitting your own, and then calling them to disconnect then you can reconnect the tails and they will seal up the cut-out.

 

[Steve Hart]

very useful advice, thank you. I'm inclined to play it safe and buy an isolator switch and get the rec to come and connect it up to the meter but what spec of isolator switch do I need?
Cheers
Steve.

 

[plugwash]

something like

http://www.tlc-direct.co.uk/Products/MK5502.html
and
http://www.tlc-direct.co.uk/Products/MK5500.html

should do it

 

[Steve Hart]

great stuff. thanks mate.