Running a new cable for shower.

[plex81]

Hi guys & gals.

I have just purchessed a new house (fixer upper) and im looking to wire in a new shower, however I am unsure of the best way to run the cable to conform with IEE wiring regs. Should it run through the loft or under floorboards?. I have a copy of the 17th edition but find it very confusing. Also do I need to run it through conduit and is there anything else I should be aware of. I will be wiring it into a 45A RCD with 10mm twin and earth over a length of about 15m. please hlep, thanks Alex

 

[sparky b]

Alex, it's notifiable work mate, you need a scheme registered electrician/competent person to do the work....

 

[plex81]

I was aware of that, but am I not able to leave it open to be checked and certifide by a certifide spark. I did this when I changed my CU

 

[sparky b]

Unfortunately not, only if they're supervising you....

 

[Lee321]

Unhelpful post deleted

 

[Riggy]

you need a scheme registered electrician/competent person to do the work....

Are you sure this is the only way?

 

[Riggy]

[quote name='Lee

 

[Zeespark]

Living in Lanarkshire, Plex doesnt have to worry about Part P, it doesnt exist in Scotland. But I would look to see if you need a building warrant for the work before you start Plex.

AndyGuinness

 

[m4tty]

[quote name='Lee

 

[plex81]

Thanks guys. for the building warrant i need to detail what im going to do. So do I run the cable through the loft or under floorboards, Dose it matter? also when i run the cable down the wall cavity to the shower dose this need to be put in conduit? cheers Alex

 

[Sidewinder]

plex,

The cable install needs to comply with the regulations as you say, but not just the cable run.

The whole new circuit must comply with the regs.

I don't know the procedure up in Scotland wrt building warrants.

Just a few things for you to think about and come back to us with.

One thing is none of us know the construction of the building.

You can run the wire under the floorboards, or through the attic.

Is this on the ground floor or an upper storey?

Where is the CU in relation to the proposed shower?

If you are going to do this via building warrant then you will have to justify any of your design decisions to the inspector if they ask.

What is the construction of the floors/ceiling and intermediate supports?

What is the situation with the main bonding and additional protection?

You "should" not drop cables unsupported down the full length of a cavity wall.

Do you have the appropriate test equipment to complete the certification, or is this covered by the building warrant scheme?

Do the building control send someone to inspect the install at various stages?

 

[NozSpark]

Leaving aside how you are going to run this cable,,,

Once it's in and connected up how are you going to ensure that it's safe to use?

Working and safe are two entirely different things!

 

[plex81]

Thanks for responce. The biulding is a top floor teneamant flat, with a slightly odd construction, the joists under the floorboards run diagonaly to the floorboards, however the joists above the celing run purpundicular to the floorboards also the noggins appear to be standard spacing appart. there is no loft insulation ( thats a job im not looking forward to). The CU is in the hall way addjacent to the barthroom and total cable required including the rise or drop is approx 15m. I have not decide on a shower as yet so not sure what power rating will be this is why im using 10mm twin and earth (might need to get a bigger mcb for my RCD protected circuit. For the testing side of things ill have a spark come and test and certifacate my work. the bonding in my house is good according th the spark that certicated my new CU. With regards to bounding the new shower plumbing i thourght this was not needed as its connected to the rcd side of my CU, however if this is required i will use bonding clamps and earth wire. With regards to designe i am able to do anything as the hole house is getting renovated

 

[ian932]

You "should" not drop cables unsupported down the full length of a cavity wall.

Not the case, you should check they are fit for purpose or that it meets the criteria of the OSG Appendix 4 item 7 (page 111) and you take note of section 522.8 of the BRB

 

[apprentice87]

Hi, not being funny, but for a start off, someone else cannot certificate your work.

Before you even start you need to make your mind up what shower you are having or otherwise how are you going to even start to calculate the cable size and MCB required.

What about all the cable related calcs you have forgotten about, that you need to size your cable properly. It is not just the rating of the shower you need. There are correction factors for where the cable is run, as in, with others, or in insulation, what about ambient temperature, volt drop, checking cpc size is adequate?

Guessing as to what the requirements for bonding etc are is not too good either!

As previous forum members have said, how are you going to test the completed installation and really importantly, please understand that like Nozspark said, working and safe, are too completely different things.

I am going to give you a bit of advice here.... I know you say you find BS7671 confusing, but go back and have a good read. The answers to all your questions are in it!!

Have a good read of appendix 4, chapter 54 and section 701

Everyone on here will try to advise you, but in the long run you would be much better off if you made a big effort to find out for yourself. You will have a much greater understanding then. There is a BIG difference between merely "knowing" [cos someone told you] and understanding...

Not trying to be critical here, I just think that you should try to understand the principles behind it all and not just try to get the shower working.

When you changed the CU, how did you test the installation afterwards?? there is lot more than just connecting it all up.... How do you know the condition of the existing wiring and what faults there may be in it all, or if the wiring is adequate for the new MCB's you installed??

How did you manage to get someone to "certificate" it all?? What sort of cert did they issue and what sort of inspecting did they do??

john.

 

[Doc Hudson]

For the testing side of things ill have a spark come and test and certificate my work. the bonding in my house is good according th the spark that certicated my new CU.

It would probably be best to direct your questions to the electrician who is going to test & certify your work, as I suspect he will have to sign regarding the design aspect and compliance with current regs. Because by you own admission you do not understand BS7671 therefore cannot sign yourself for the design compliance aspect. I am unclear of the logic of asking persons with no experience of the property over someone who has got both qualifications and first hand experience of the property?

Doc H.

 

[ian932]

Hi, not being funny, but for a start off, someone else cannot certificate your work. - Yes they can happens in the real world every day as long as its inspected at key stagesBefore you even start you need to make your mind up what shower you are having or otherwise how are you going to even start to calculate the cable size and MCB required. - He is running a 10mm at 15m so he has made allowance for the max shower size on the market

What about all the cable related calcs you have forgotten about, that you need to size your cable properly. It is not just the rating of the shower you need. There are correction factors for where the cable is run, as in, with others, or in insulation, what about ambient temperature, volt drop, checking cpc size is adequate? - Its 10mm T&E cable over 15m the cpc is part of it and likely to be adequate in 25 years of working on domestic jobs with showers over this distance I cannot recall one where that was not suitable. But I'm sure he will ask his electrician to check it for him. Give the guy some slack he is here asking and not just doing it.

Guessing as to what the requirements for bonding etc are is not too good either! - Thats why he is asking questions! and he said his spark signed it off during a CU upgrade

As previous forum members have said, how are you going to test the completed installation and really importantly, please understand that like Nozspark said, working and safe, are too completely different things. - He answered that in his last post, he is using the electrician that did his CU upgrade to test it.

I am going to give you a bit of advice here.... I know you say you find BS7671 confusing, but go back and have a good read. The answers to all your questions are in it!! - Not all his questions are within the BRB, more practical ones are not hence the reason the OP is asking questions and if the BRB had all the answers to all things electrical there would no forum cus we would all read the book

Have a good read of appendix 4, chapter 54 and section 701

Everyone on here will try to advise you, but in the long run you would be much better off if you made a big effort to find out for yourself. You will have a much greater understanding then. There is a BIG difference between merely "knowing" [cos someone told you] and understanding... - WHAT!!! Get off your box, that

 

[matt.leung]

yeah, stop being bitchy, he is asking questions that the BRB can not answer, not everyone knows everything, thats why is forum is here, to help each other.....

 

[monkey5]

i would find the electrician who will be the final person to test and sign off the shower supply before you continue and ask him how he would prefer it to be done as it would be his name signing it off. doing this first he might have an easier/better way to run the cable and then theres no worries afterthat he wont sign it off.

HTH wayne

 

[matt.leung]

I am working in a house, where their shower supply comes out the CU in T&