not sure what unit the current regs require but I currently have 2 socket ring mains , 2 lighting circuits, 1 immersion heater, 1 cooker and 2 spares rough price and hours to fit would be nice (I could fit it myself but just worried about breaking the seal on the "company fuse")
sorry forgot to add a flush mounted one is required as its on full view and at head height in the hall
We just had the same problem. Cheapest quote was £275 for supply and installation of a CU complying with 17th edition regulations and fully certified. Most expensive was £480 for same specification.
Kevin coughed up some electrons that declared:
Hi,
This will give you some idea of the parts cost:
Depending on your current setup, add some crimps and bits of cable if any of the current cables may not be long enough (quite possible as it's a flush mount - may be no slack on the existing cables).
Miscellaneous parts for any remedial costs, eg making good earth bonding and the odd repair.
I think if you get quoted 350-500 all in, you're doing well as a CU change done by the book requires testing the final circuits (consider it a health check on the system and it won't feel so bad). The bloke will only get about half in labour "wages" as it might first appear due to all the overheads of taxes, professional body membership, test gear and insurance.
Although that unit in the link is bigger that what you need, most of the cost is in the 2 RCDs and the common parts - it won't get much cheaper to have a few less ways.
In your scenario, the customary way to distribute circuits would be something like:
RCD1 Downstairs lights + upstairs sockets
RCD2 Upstairs lights and downstairs sockets
Then split up the other circuits about half and half by load and put half on RCD1 and the others on RCD2
If you have any smoke alarms on their own circuit, these can go on an RCBO on the non RCD busbar.
Cheers
Tim
Watch who you get in as this type of work is often seen as an invitation to do a full rewire, rip you off and cause a lot of mess which youdon't need. A consumer unit can start at £35 complete with 10 MCBs of values of your choice. They can also go up to over £100 depending on the style you want. I replaced mine for £35 and it took about 30mins as all the cables were long enough. People taking two or three hours, stringing the job out, then claiming not to be able to connect anything up unless you agree to a rewire are cowboys. What they should be doing before starting is giving you the opportunity to pay for a full test if you want it, then they will have a better idea of whether they feel confident to do the job or not. Most visual inspections are OK to give an idea of the state of wiring. Contractors are like garages now, not to be trusted, they have a set figure in their mind that they want to get from you - so will lie to get it.
Ian coughed up some electrons that declared:
Actually, if they are doing it correctly they *must* at least perform a basic test of the final circuits. I know because I've just done the EAL Level 2 Domestic Installer's course (and passed), which is the entry level qualification to join a DI self certification scheme.
I'm also doing it for the purposes of DIY (to make the BCO feel warm and fluffy about accepting my work and certification with no further checks) so I don't have an axe to grind, but I think some understanding is needed, so forgive me for speaking up :-)
The reason is, changing the circuit protection requires the circuit to be checked to ensure the disconnection times are correct (0.4 seconds on a final circuit upto 32A and 5 seconds on any other circuit).
You can only prove this by taking a Live-Earth loop resistance test (a multimeter, unless *very* sensitive will not manage this reliably) and combining with the supplier's Earth Loop Impedance value (which requires an earth loop impedance meter to measure). Even assuming the worst case supplier's Ze impedance of 0.8 ohm for TN-S and 0.35 ohm for TN-C-S, it still needs to be checked.
A high resistance circuit may fail to trip the breaker quickly enough under fault conditions and instead leave your cabling running hot (fire and cable damage risk). I accept RCDs lessen this risk on L-E faults, but on L-N faults the point stands.
You're also supposed to complete an EIC when changing circuit protection to comply with the IEE Regs (changing the CU results in changing the protection on many circuits) and apart from the above checks which are recorded, you also need to check insulation resistance at 500V.
RCDs need to be checked for correct operation at specified levels even if new (test button is one test but is not sufficient by itself).
You cannot really expect a professional who is subject to the standards of his professional body (eg NICEIC, NAPIT etc) *and* his insurers *and* the IEE/IET to not do the job correctly - eg if you didn't like something he did, you could ask his body to inspect his work and any shortcuts will get him/her into trouble.
But your point about needless rewires is quite valid - unless the circuit is actually faulty, having RCDs on everything address most of the changes in the 17th Edition affecting domestic work that are likely to be an issue.
The testing involved could take a few hours to conduct in a larger house and a good hour or two on a small installation.
Of course, if you're doing yourself, without notifying and you feel confident that all your wiring is good, then I agree that 30 mins is quite possible. But the sparks you employ wouldn't be able to make those assumptions. So it's not necessarily the case that they're ripping you off if it takes 1/2 a day to a day depending on any faults that may be discovered.
Cheers
Tim
Not sure I follow the logic. Very few electricians would be prepared to change a CU on its own if the rest of the wiring was in a dangerous state.
Being realistic you probably need to budget more for a decent 17th edition CU and 10 MCBs... the RCDs alone are likely to be pushing £30 for a pair.
This is misleading. Yes you can complete the mechanics of swapping one CU for another in 30 mins if you are lucky, and its a simple layout without many ways. However you are not going to be able to do adequate testing in that time. There is also a good likelihood that other work will be required before the new installation is to an adequate standard
- e.g. bringing the main equipotential bonding up to spec.
If you are quoting a fixed price for the job, you also have to budget for potential problems that may not be visible until after the initial work is done. What happens when a previously non RCD protected circuit now trips the RCD? How would the customer feel if the electrician turned round and said, sorry can't get power on to that socket circuit - there must be a fault in there somewhere, but fixing that is not included in the price?
The testing aspects of installing a new CU are not optional (at least not for a professional).
The devil, as always, is in the detail. Visual inspections don't give you the detail. It is often easy enough to spot the installations where it would be unsafe to do any work without also doing a full or partial rewire, however the systems that "look ok" but have hidden problems can take far more fixing.
Alternatively the contractors are honest and up front about the real and potential costs, and the customer is a clueless tightwad who thinks the world is out to screw them. Works both ways.
I think the above is the crux of it - attaching a new consumer unit to an old installation is highly likely to highlight hitherto-undetected faults which mucxt be traced and rectified before the new CU can be wired up.
Personally, I've twice in the past undertaken full rewires of properties I've been renovating; in both cases the plan was to start by replacing the CU and hooking it up to the old wiring, which I would then replace piecemeal. However in *both* cases the RCDs tripped immediately (despite both properties having up-and-running electrics previously). I judged it wasn't worthwhile tracing the faults and just wired up one new double socket to provide temporary power while I did all the rewiring.
Admittedly the wiring was in a pretty poor state (which was why I'd planned on replacing it) - hopefully yours isn't so bad!
David
Mate paid £400 to replace a unit that had fuses of one with MCBs
Where did you do that, how long and at what cost, if you don't mind? I'd be interested in a similar course. Thansk Alan.
A.Lee coughed up some electrons that declared:
Here:
These guys do something similar, near Gatwick:
For me, pleasingly, my usual standard of work was validated (that's a confidence boost to know you are actually doing it right), but I did pick up some new tricks and some extra good practise. It's also useful having some practical context given to using the OnSite Guide - it's quite easy to extrapolate from that to fill in the missing bits later.
The exams are easy enough (all multiple-choice). If you can hack V=IR, P=VI and generally hold a tool the right way up, you'll not have any trouble benefitting from the course and passing the exams.
It cost, but if I add this to buying a second hand Megger to do the testing, I'm still about 3k better off compared to paying someone to do a full rewire for me, and that's on one job.
If you are cool with general working, but fancy studying the testing, they told me they are starting a C&G 2392 course, which is a foundation in inspection and testing. It's designed as a precursor to the 2391 for people without a comprehensive practical background.
I'm going to have a go at the C&G 2382 (17th Edition Regulations) next. I'm going to just try sitting the exam with the IET without the course as they seem the cheapest way to do this. Trying a past 2381 paper has been favourable.
Cheers
Tim
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