Running a new cable for shower.

[ian932]

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.

Its for the OP to answer but it could be that he wants to make a start and is unable to get hold of his spark due to it being Easter etc. Whilst its very sound advice Doc sometimes people also think they will get charged for asking their spark in to advice and we give it here for free

 

[Sidewinder]

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

ian,

IMHO there are other factors to consider other than the brb.

Also, the brb is the minimum level of compliance.

I would not allow this to be done on one of my designs, in fact it would be prohibited in the spec.

So as I said, and why I put the "should" in quotes as I believe that is should not be done, just because it complies barely possibly depending on the exact situation does not make it sound engineering judgement.

Please remember that it can be cheaper over the life of an installation to ignore the cable sizes given in the book and calculate your own for large loads which are heavily utilised.

This does not make it non compliant.

I have (not my design) seen machiens with over 300A total connected load supplied with 35mmsq swa and compliant with the regs in force at the time.

This was a design calculation based on capital expenditure on cable rather than whole life cycle costs.

 

[Lee321]

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.....

yes for us electricians not for some diyer to potentially kill someone and second do sparks out of work

 

[apprentice87]

Hi Ian932,

You took my comments in exactly the wrong way! I was trying to help the bloke learn, not put him off, but first i have to correct a few points you made:

1,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 stages"

It may well happen, but it does not make it right!! The first words on an EIC are "I being the person responsible for the design, construction, inspection and testing" blah blah"

I stand by my comments, you cannot legally sign off someone elses work. I suppose you could if you stood there for every part of the job, but that would still only be borderline legal and would defeat the object of the exercise anyway, as the person doing the signing might as well have done the job himself.

How you going to inspect and sign off things that are now possibly covered up?? Say i install a cable, how do you know that i have not bent it too sharply, or that it is not in contact with sharp edges, or that i have not otherwise damaged it unless you are there when i install it?? bit late just inspecting the ends sticking out later!

2, 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.

- "He is running a 10mm at 15m so he has made allowance for the max shower size on the market"

10.8kw at 230v = 47 amp but 10mm twin and earth, installation method 100 or 101 [above a plasterboard ceiling with respectively up to, and over 100mm insulation] is rated at 45A in the first case, and 36A in the second [OSG page 134 + page 282 in the BRB]

3,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"

Spark should not have signed it off as the OP clearly stated he INSTALLED THE CU HIMSELF.

4, 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"

As above, the OP stated he did the CU himself.

5,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"

What questions are not in the BRB then??

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

 

[ian932]

ian,IMHO there are other factors to consider other than the brb.

Also, the brb is the minimum level of compliance.

I would not allow this to be done on one of my designs, in fact it would be prohibited in the spec.

So as I said, and why I put the "should" in quotes as I believe that is should not be done, just because it complies barely possibly depending on the exact situation does not make it sound engineering judgement.

Please remember that it can be cheaper over the life of an installation to ignore the cable sizes given in the book and calculate your own for large loads which are heavily utilised.

This does not make it non compliant.

I have (not my design) seen machiens with over 300A total connected load supplied with 35mmsq swa and compliant with the regs in force at the time.

This was a design calculation based on capital expenditure on cable rather than whole life cycle costs.

Sidewinder, Don

 

[Sidewinder]

ian,

That is why I put "should" in inverted commas.

IF it had been direct from the regs, then I would have quoted that.

It is from my engineering judgement that I feel that unsupported cable runs down cavities are unsuitable and should be avoided where possible.

I base this on information in the brb, my experience, the mass of the cable, likely external influences.

There are a host of other possible issues that can come up in doing this.

I don't read any clause in 522.8 specifically allowing cables to be run unsupported in the cavity of a wall, at least not in the copy of BS7671:2008 I have.

My osg & GN1 are not at the pc at the moment, as I have just popped on to have a mooch whilst having a break.

You are suggesting as I read it that the brb specifically allows this, I would have to disagree, IMHO it does not specifically allow this.

HOWEVER, it is NOT specifically disallowed either as long as you can ensure that the clauses in 522.8 are met along with others, and the requirements of the building regulations for the lifetime of the installation.

Finally as i have to dash, sometimes there are no other options, also cables do have to break cavities and sometimes run through, however, the OP is gutting the premises so I feel that a more suitable route should be found.

A soil stack riser is a different kettle of fish to a cavity.

This again is a risk of the medium, I TRIED to highlight the "SHOULD" and did NOT state that it was regs in an attempt to differentiate it from the rest of the post.

 

[ian932]

[quote name='Lee

 

[Doc Hudson]

Its for the OP to answer but it could be that he wants to make a start and is unable to get hold of his spark due to it being Easter etc. Whilst its very sound advice Doc sometimes people also think they will get charged for asking their spark in to advice and we give it here for free

However persons who already have previous work done by an electrician, normally have a fair idea of their costings and most often have a mobile or email contact as well. Your assumptions of uncertainty over charges are more common when ringing a new electrician cold. Which is not the case here, apparently. As the OP is specifically asking about cable routes, not cable sizes, if it is not being clipped on the surface, a.n. other electrician may not be able to fully confirm compliance with BS7671 & building regs. No matter how free our advice is. I would still suggest a site meeting with the electrician who will be signing any certificates is the only sensible way to proceed without the risk of needing to redo part of the work twice.

Doc H.

 

[ian932]

I take on board all you have said and I believe it would have been better to put

 

[sparky b]

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

That'll teach me to open my mouth before reading things properly.....That's why I never normally post late at night due to the:Y, my bad :Blushing apologies Plex.....

 

[Zeespark]

Sparky_B, we are all guilty of it at one time or another, not to worry

AndyGuinness

 

[ian932]

most often have a mobile or email contact as well.

I would not ring a tradesman on a Bank Holiday to try and obtain some advice if I wanted to crack on with something over the w/e, but I would ask on a forum if there were people on it.

Your assumptions of uncertainty over charges are more common when ringing a new electrician cold. Which is not the case here.

I made no assumption I merely offered a possible reason based on a question you raised and granted it is likely he would know the charges if it

 

[plex81]

Hi guys thanks for the replies. Im sorry for all the hastle I caused. For the record I am no DIYer and safty is my bigist concern as its not just me that would be using the shower. I am a compatent engineer, I worked as a sparks apprentice for 2 years with the water board and had to change to mechanical for company reasons and also because i am heavly dyslexic and had trouble studying the books this is why i prefure to ask questions hear, as the answers are genrally easy to understand. Altho I changed from electrical to mechanical I worked very closly with the spark for the next 7 years as he did with me on mechanical jobs. during this time I obtained an electrical qualifaction with a recognised training body EMTA, and I currently work as a matinance spark, however this dose not make me a fully qualifide spark. I was just wanting to know the best practice for running the cable. with regaurds to having it tested and inspected I leave it all open ie the floor boards are left up the chased wall with conduit running through it is left uncoverd intill he has checked it and tested it. Once again i am sorry for any trouble that i may have caused. Cheers Alex

 

[Zeespark]

Its no trouble Alex, there are no major issues with running the cable between the floorboards providing its done to the regs or even better, which I believe we should all be doing.

AndyGuinness

 

[plex81]

Thanks Ian932 that was what I wanted to know. I should have used the term 1st fix then I might have stopped some of the confusion. thanks

 

[NozSpark]

Thats not a problem Alex,,

I hope that somewhere in there you got a reply that will help you with what you are planning on doing..

Unfortunately sometimes we get asked questions by people who dont have the skills to carry out electrical work, however with your additional information (above) you seem to be reasonably switched on. However in your circumstance where you have someone who will test the work for you, I would suggest that you get their approval of the routes that the cable needs to take... Personally I would not take kindly to a "fait au complis" for work that I was "supervising"

 

[plex81]

Thats not a problem Alex,,I hope that somewhere in there you got a reply that will help you with what you are planning on doing..

Unfortunately sometimes we get asked questions by people who dont have the skills to carry out electrical work, however with your additional information (above) you seem to be reasonably switched on. However in your circumstance where you have someone who will test the work for you, I would suggest that you get their approval of the routes that the cable needs to take... Personally I would not take kindly to a "fait au complis" for work that I was "supervising"[/QUOT

Thanks. I will give the guy a call. I purchessed the simplafide version of the IEE wireing regs today much easyer to understand, thank god

 

[NozSpark]

TBH there are a whole host of different regs that you need to be aware of; and that is what your problem really is,, where and how to route and fix your cable so that the end job will comply with all the appropriate regs

 

[Doc Hudson]

I would not ring a tradesman on a Bank Holiday to try and obtain some advice if I wanted to crack on with something over the w/e, but I would ask on a forum if there were people on it.I made no assumption I merely offered a possible reason based on a question you raised and granted it is likely he would know the charges if it

 

[Lee321]

my apologies alex/anyone. sometimes we jump in with both feet