Job questions

[Dazz0i]

We've got an extension job at work, shell is up and first fix is about to start.

The plans state interlinked smoke alarm's with battery back up to be installed if not inplace already.... (which they're not)

The consumer unit is the old style wylex (5 way i think from memory), which looks like it'd have ones had semi-enclosed fuses, but've been changed out for plug in MBC's. This board has no space left in it.

Am i right in thinkin' that the smoke alarm's need to be on their own circuit? (As i know this is how we were doing them on our newbuilds.) If so, that'll mean an update of consumer unit, at which point then..... Don't all circuits being connected to it, have to conform to latest standards/regs?

Which is then where it's gonna start getting expensive.... the main earth's aren't 10mm, meter tails aren't 25mm.
I'm also pretty sure that all the sockets currently are on a single 30amp breaker, would this need splitting?

(All work will be checked by LABC as the job won't get signed off without certification.)

Cheers in advance.

 

[Spark123]

If any work involves unprotected concealed cables <50mm then the cables need to be on a 30mA max RCD. This may as well be on a new CU.
If the MEBs are not up to standard then this need to be corrected as it is a fundamental requirement of BS7671.

 

[plugwash]

The wiring in the new section will certainly have to be up to current standards which for a domestic basically means either RCD protecting everything (there are other options but they are unlikely to be economical) That will probablly mean a new CU regardless of the smoke alarms issue.

Getting back to the topic of the post smoke alarms can be on either a dedicated circuit or a local lighting circuit. The trouble is if interlinking you generally want all the smoke alarms on the same circuit as each other and there is no one lighing circuit that is local to everywhere in the property. Therefore the simplest option is usually to put them on thier own circuit.

As for when and if existing wiring that is being left in place needs to be upgraded to meet current regs this is an issue that sparkies are divided on. Neither part P nor BS7671 has much to say on this topic beyond saying that bonding should be checked and brought up to current standards. Some sparkies believe that if you replace a CU you become responsible for everything downstream of it and as such must ensure it meets current regs, others don't.

 

[Dazz0i]

yea, the use of an RCD equipt board will happen.

Does this mean we've got to tell the customer that due to a new CU being installed that they possibly need a lot of their house re-wiring/alterations to bring their house up to spec'?

off top of my head, it's got 2 lighting loops, 1 alarm feed, 6mm cooker, 4mm immersion and a single final ring.

which means no dedicated final ring in the kitchen. No dedicated smoke feed. I'd also assume that the boiler has been spured from a socket in the bedroom....

 

[Dazz0i]

was writing that last post as you replied plugwash.

interlinking the smokes shouldn't be a problem.

as they've got a 5way board atm..... i'm thinking, unless they want to fork out to have a lot of work done to update their house. get a board with space in it, and wire all new circuits onto their own breakers and leave the house as, but in the new board? That would obviously make the house wiring RCD protected. (That then could un-cover some problems they never knew about, but thats a different story and then out of their control to have sorted)

Dont want to be making the final ring any bigger than it already is, and as the board is in the garage and the building work is above the garage, it's no problem to create a completely new circuit.

 

[plugwash]

This post is written assuming you are a general builder who plans to do the first fix themselves but then call an electrician for the connection/inspection/testing. Please correct me if I am wrong.

which means no dedicated final ring in the kitchen.

There isn't any reg explicilty requiring a dedicated ring in the kitchen, just more general regs that say things like the instalation should be adequte for it's requirements and rings should be reasonablly balanced. I can't imagine most electricians worrying about this on an existing install but check with yours.

No dedicated smoke feed.

So your new interlinked smoke alarms will be a from scratch job (typically 3+E is used to carry both the power and the interlink wire) on a new circuit.

I'd also assume that the boiler has been spured from a socket in the bedroom....

Perfectly normal.

In other words unless there is something badly wrong with the installation that you haven't told us about I would expect a new circuit for the smoke alarms and possiblly some other work to fix small noncompliances elsewhere (missing sleeving, borrowed neutrals on up/down two way lighting, stuff like that) we don't elsewhere. Plus whatever wiring work (either new circuits or extentions to existing ones) is needed for stuff in the new extension.

You really need to get your electrician out to take a look at the existing wiring and tell you what he wants doing before you start first fixing.

 

[Dazz0i]

Correct, we're a building company, and do all "in house". Till recently we had a spark on board who i'd ask all this, even then, i'd do the manual work, he'd do the thinking (he was the boss, so didn't have to do anything)....... but now don't. So, as said in OP all will be checked by LABC as we know that offically no other spark should test/certificate anyone else's work. I've got the joy's of doing first/second fix etc....and plan to start the 2330 in sept.

Correct again, 3+earth for smokes.

If need not, will try not to go into the house wiring.

 

[plugwash]

So, as said in OP all will be checked by LABC as we know that offically no other spark should test/certificate anyone else's work. I've got the joy's of doing first/second fix etc

I think you really need to get an electrician involved or do a LOT of reading up, help from a forum post like this can only go so far.

If need not, will try not to go into the house wiring.

Much better to determine if there are any significant issues (old rubber cable, borrowed neutrals, undersized cable, failing insulation, main earth problems, bonding problems etc etc) with the existing wiring at this point before you move forward than to have them bite you in the ass later.

wire all new circuits onto their own breakers and leave the house as, but in the new board?

Putting the extention on seperate circuits seems like a sensible move since it will make the wiring less disruptive and allow it's isolation without cutting all power to the house plus as you say it avoids extending the already rather big ring any further.

That would obviously make the house wiring RCD protected

You also need to decide how to handle the RCD protection. Putting the whole house on one RCD is not generally considered acceptable anymore. The best soloution is RCBOs, that way each circuit has seperate RCD protection minimising the disruption caused by a RCD trip and making the fault easier to track down but this can be a little pricy. Dual RCD boards are a compromise allowing some splitting between RCDs without the cost of a RCBO for every circuit.

 

[Dazz0i]

it'll be a split load board with dual RCD. Not sure if it'll be one with a section that's non-RCD protected, for possible usage of RCBO's.

certainly agree on internet can only help so far, which the reason for wanting to do work myself, but make sure it's safe and legal at the same time. plus the reason for qualifying myself. sucks it takes soooo long to do so though.

pretty certain it's not rubber cable as all the ones back to the board aren't rubber....

things like failing insulation and earthing problems, i can't test for, but would show up on the final test... ok i know it's not the best time to work this out, but cost of rectifying the exisiting wiring problems isn't "our job" so to speak, that'd be an extra, and wouldn't matter if it was to be sorted now, or at the end of the extension. I can't see the customer wanting to pay for a test twice. Other wise, i'd be in full agreement with doing one now and telling them "this is what it'd cost to solve all...".

 

[Dazz0i]

Appreciate all your input though!

 

[ericmark]

Be very careful reading second hand info. I will give some examples. I do not need to protect cables buried in the wall by a RCD in my house. Neither does any other Electrician because we are Electricians although I always would because of 522.6.7 and when I read your first post you said

We've got an extension job at work

which I read as being in a factory or similar.

Only when I read further did I realise it was a domestic. Even then for smoke alarms using an Ali-tube cable to BS 8436 you still would not need RCD protection. Again careful as not all Ali-tube is to BS 8436 some is to FP200 for example and some complies with both standards.

Also from what I see you are not DIY so you must insure and I would question if your insurance will cover if the installation is designed and installed by personnel who have not been trained or employed as the appropriate tradesman. I was trained as an Electrician but when I went to work on building of second seven crossing was employed as a charge-hand mechanic as a way to boost my wages. Then after a few months the Electrical superintendent realised that the insurance would not cover me and had to stop me working on fixed electrical equipment. I still worked on the straddle carrier which was 400vac which did seem crazy but that was a vehicle so I was allowed. I still officially laboured for electricians though in reality they laboured for me as I had the special skills required for some of the complex machines we had.

In theory when Part P is through the LABC they are responsible for site safety but in practice I would not be too sure if that would include the professional indemnity insurance required to give advice. All is great until something goes wrong. Then the HSE get involved and everything goes pear shaped.

I like any other electrician have broken the rules many times. I know I am not following the rules and I make a risk assessment not necessary in writing but just in my own thoughts as to if what I am doing wrong is likely to get me into trouble. However someone watching me could think what I am doing is OK and I am not likely to admit except maybe to an apprentice that I am not following the rules. For example standing on the purling to drag through a new cable. But when there is someone watching who may report me then I would not brake the rule. However someone copying me may not realise this and continue doing it when the HSE or LABC is on site. One guy did this where I was Electrical Engineer and I had to sack him. Pitty as he was a good worker. But it was only way I could get out of a sticky problem with HSE. Had I been caught both company and myself would have been in court.

Do remember the Electricity at work act does cover you. It does not cover a DIY'er so do be very careful what you do.

 

[Dazz0i]

You've raise a good point there.

As far as i'm aware, the LABC does cover it, but i could be wrong. We used to build new builds, and this was how we did the wiring in them. I did a lot of the wiring/electrical in them too, which all passed ok. BC knew we were a trading company.

 

[securespark]

Even then for smoke alarms using an Ali-tube cable to BS 8436 you still would not need RCD protection.

You wouldn't for T&E, providing it was surface-mounted on the walls.

 

[Dazz0i]

will be consealed, so will have to be RCD'd.

This won't be too much of a problem damage wise, kitchen ceiling is comin' down so just need to space it through partition wall into the hall ceiling, then obviously the 3 core to take the same path and carry on up to the one on the first floor.