first cu change, advice would be nice

[loz]

I'm in my 4th year of my apprenticeship and consider myself quite competent. The downside is that i have only worked with underground cabling on caravan site distribution.

My dad has asked me to change his cu in his house as he wants to update it. the current situation is old 6 way 3036 board, tt earthing, no main bonding but a 6mm supplementary bond to the shower. The cable going to the tt rod is currently a 6mm.

My plan is to install a 10 way dual rcd board, 10mm main bond at point of entry on the copper water pipe, run a 16mm earth to a new rod and pit in the front garden (id like to aim for <50 ohms.

My quiestion is does the cu need to be protected by a separate 100mA rcd or is it ok to rely on the 2 30mA rcds in the board?

Also is it best to reconnect the 6mm supplementary bond to the shower? or leave disconnected?

Also should i leave the existing earth rod and 6mm cable connected to create a better earth? (current readin to rod is around 60ohms (main earth disconnected to test) , boards readiing is 0.29 due to supp bonding being in plaice

Any help would be much appreciated, loz

 

[Zeespark]

Have you informed your local LABC about your plans Loz?

AndyGuinness

 

[loz]

NO, not yet, i want to make sure i know i will be doing the job properly before we do that, as if i dont know its getting done properly then ill just say to him i dont feel confident doing it, youll have to get somebody else to do it. But if i do do it, then yes i will inform labc before i carry out any works

 

[NozSpark]

Like Zeespark says you should inform your Dads LABC (and pay the fee) that you are replacing his CU at least 2 days before you start the work.

The only other thing that I'd say is that if you are leaving the old rod connected then they should be at least twice as far apart as they are deep,,, IYKWIM?

---------- Post Auto-Merged at 19:14 ---------- Previous post was made at 19:14 ----------

Oh,,,

And supplementary bonding does not go back to the CU

 

[loz]

Like Zeespark says you should inform your Dads LABC (and pay the fee) that you are replacing his CU at least 2 days before you start the work.The only other thing that I'd say is that if you are leaving the old rod connected then they should be at least twice as far apart as they are deep,,, IYKWIM?

---------- Post Auto-Merged at 19:14 ---------- Previous post was made at 19:14 ----------

Oh,,,

And supplementary bonding does not go back to the CU

yeah i know what you mean about the rods, my mistake with the supp bond, the cable runs to the shower direct from the cu (proved with a continuity tester and a r2 wander lead)

 

[M107]

My quiestion is does the cu need to be protected by a separate 100mA rcd

Not if it's an insulated cu.

is it ok to rely on the 2 30mA rcds in the board?

It is

Also should i leave the existing earth rod and 6mm cable connected to create a better earth

You could use it & not bother putting in a new one (fit an enclosure obviously).

Also is it best to reconnect the 6mm supplementary bond to the shower? or leave disconnected

So long as you meet the requirements of the regs you could ommit the supplimentary bonding altogether.

 

[Manator]

To be brutal and totally honest? No I would not say your competant to carry out this works. Could you do it? Yes I think a forth year student could, but, and the main reason for my reply is, everyone assumes that they can carry out any electrical works without any comeback , however if prosecuted, it will not come from argument in competancy, it will come through various agencies which sidewinder constantly reminds us of.

 

[johninlondon1]

To be safe why not employ a competent experienced electrician to do the work with you as the understudy and you asking lots of questions, this will give you peace of mind that the job is 100% and give you some more valuable experience. People will always respect someone that admits that something maybe beyond their experience and competence instead of being all macho and giving it a go with possible bad consequences. Electricity kills people, and this should always be at the forefront of any thinking before doing anything that your not 100% sure of. Better to appear useless than blunder along making a bad job and put people and property at risk.

 

[SPECIAL LOCATION]

What books and test equipment have you got permanent access to Loz?

A lot of your questions will be answered in BS7671 / On-Site-Guide / GN3 / GN1 / Approved Document P.

Are you up to speed and confident with the testing of all the circuits?

Checking for things like borrowed neutrals etc.....

Just asking cuz I do know of a lot of sparks who are top notch at getting cables in and terminated, quickly, efficiently and look a quality job....

But when it comes to the testing and verifying compliance with 7671 the really haven

 

[loz]

hey, thanks for the replies, special location, i have access to a full avo/megger test kit and am confident in using it, the work i do involves alot of testing on 2000 pitch caravan sites, i also understand testing of buildings and have had a bit of practice, i know i could carry out all the tests and also know what my expected results SHOULD be if there are no faults,it would just take me longer than guys doing it day in day out. I have a copy of bs7671 ammendment 1, osg, gn3 and nicc testing and inspection, 5th edition. I think what i will do is test the full installation as it is to confirm there are no issues with the current installation, then have a word with an ex colleague who has done alot of domestic work and is also a nicc member and part p registered, to see if he will give me a helping hand with the change so he can point out where im going wrong, if i am. Also with him helping me and being on site for the duration would he be able to register it with the labc through the nicc to make things easy?

thanks for the advice.

loz

ps this domestic mallarkys a ball ache, give me a 300x4c resin joint any day

 

[NozSpark]

TBH that sounds like a good plan.

A. Find out the current condition,, and

B. Do the work whilst supervised by a registered guy and get him to register it

Some LABCs won't entertain non registered guys doing part p work, whilst others could charge you more than it would cost to get a registered guy to do the job from the off

 

[SPECIAL LOCATION]

That sounds like a plan to me! Guinness

100% agree, give it a full & thorough test BEFORE you change the CU over.... :Applaud

it could easily save you loads of wasted time later! :Salute

 

[loz]

That sounds like a plan to me! Guinness 100% agree, give it a full & thorough test BEFORE you change the CU over.... :Applaud

it could easily save you loads of wasted time later! :Salute

its all practice aswell

cheers for the advice guys, i want to learn more about domestic wiring and have been reading this forum for a while, but i just dont get any of it to do practically at work, nearest i get is putting a t+e from a streetlight cut out up to the head

 

[batty]

So at present there is no RCD protection and you are getting a earth loop of .29 ohms at shower?

 

[Doc Hudson]

I think the OP said due to bonding. (in place.)

boards readiing is 0.29 due to supp bonding being in plaice

Doc H.

---------- Post Auto-Merged at 12:00 ---------- Previous post was made at 11:55 ----------

hey, thanks for the replies, special location, i have access to a full avo/megger test kit and am confident in using it, the work i do involves alot of testing on 2000 pitch caravan sites, i also understand testing of buildings and have had a bit of practice, i know i could carry out all the tests and also know what my expected results SHOULD be if there are no faults,it would just take me longer than guys doing it day in day out. I have a copy of bs7671 ammendment 1, osg, gn3 and nicc testing and inspection, 5th edition. I think what i will do is test the full installation as it is to confirm there are no issues with the current installation, then have a word with an ex colleague who has done alot of domestic work and is also a nicc member and part p registered, to see if he will give me a helping hand with the change so he can point out where im going wrong, if i am. Also with him helping me and being on site for the duration would he be able to register it with the labc through the nicc to make things easy? thanks for the advice.

loz

ps this domestic mallarkys a ball ache, give me a 300x4c resin joint any day

That sounds like a sensible course of action to me. The only thing I would add is please try to take some before and after photographs to load onto our "Your Pictures" forum. It would also be good to see some photos of your more day to day heavier duty work, (300x4c resin joints etc.)

Doc H.

 

[Evans Electric]

Loz, go for it , overseen by your NICIC guy , best way to learn . Your post comes across as sensible and knowledgable .

If the board is an old 3036, your dad's wiring may be 13th or 14th edition so as said above, make some pre-tests . Main one is look for a "Borrowed " neutral on the landing light as this will give you RCD tripping trouble and prevent you from splitting the light circuits between up and down.