Replace consumer unit only?

I've nearly re-wired the power circuits in our house. It's been a slow job.
The old wiring was safe (plastic, not rubber - and professionally tested as being OK), but the number of sockets was totally inadequate (except in the kitchen - a later extension).
I have no intention of re wiring the lighting circuits (or the kitchen), as they seem sound, and the installation was professionally tested last year as being OK. The tests were the resistance from live to neutral at 500V DC (greater than 20M) and the fault impedance (something small and well within limits - not sure between where and where it was tested though). The wiring dates from the late 1970s (commenced 1978).
My question is: is it OK to simply replace the old fuse box with a new consumer unit at this time?
I've read a few threads on here which seem to infer that you should only replace the consumer unit if you have replaced everything else downstream with latest regs compliant circuits. Is this true?
If everything does have to meet current regs, am I correct in assuming that a 20 year old lighting circuit will meet current regs? What about the kitchen power circuit? (Earth bonding is correct - I've checked). I'm thinking that the designs of the circuit should be OK (?) but that I should test (or get someone else to test) the circuits again anyway?
I'm aware of earth bonding issues in the bathroom (difficult to get under the bath until it's replaced) and the need for interconnected mains smoke alarms (we have battery ones at present - half the wiring for mains ones is in).
All the above isn't to suggest an intended lack of compliance with the regs. It's to suggest that it suits me to do this job in stages (all big parts before April!) but the most logical next stage is the consumer unit. This may leave some downstream parts non-compliant for several months - is this OK or a big no-no?
Thanks for the help, David.
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Do it. If the downstream stuff is non-compliant, then it is even more important to have a decent consumer unit!
It sounds like your stuff is all compliant anyway. Provided earth loop impedence and insulation resistance is up to scratch, it sounds pretty compliant anyway. Choose the new consumer unit carefully. Best is a non-split load insulated unit with RCBOs for socket outlets and other circuits requiring RCD protection. The cheaper solution is a split load unit with a 30mA RCD shared amongst all those circuits.

The requirement for mains smoke detectors is from building regulations, not wiring regulations. In your situation, you're probably aren't even required to have them, although it is a VERY good idea to install them anyway. Ensure you buy the right types and position correctly. You should not put a smoke detector near a kitchen. A heat detector type should be used in the kitchen itself. A mixture of ionising and optical types should be used elsewhere, having perused all the regulations and suggestions about siting. Use types with battery backups. Although non-battery ones are allowed, you are toying with people's lives.

Very likely. Provided it is PVC insulated and has an earthing conductor correctly terminated at both ends, it should be OK. It's hard to make a lighting circuit not comply with earth loop impedence and voltage drop. You've already had insulation resistance checked.
Christian.
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On Tue, 27 Jan 2004 14:35:34 -0000, "Christian McArdle"

Nothing wrong with that, but the ones with capacitor are more maintenance free in that they last longer than the batteries. You will still have to carry out the usual safety checks though.

SJW A.C.S. Ltd.
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a view to 'upgrading' my installation. The instructions say that the battery should be replaced every 12 months, so with that in mind I could see no advantage over a battery only model which also needs a new battery every 12 months - (I returned them!)
On the other hand, what I've now decided to buy is the following smoke alarm that replaces a standard ceiling rose: http://www.tlc-direct.co.uk/Products/HS724.html This has the advantage of turning on your light in the event of a fire or in the event of a power loss. Sounds like an incredibly useful piece of kit for 25, and as far as I can tell will satisy the requirements of having a mains smoke alarm whilst providing the extra benefit of illuminating an escape route, (or simply illuminating the path to your consumer unit in the event of an MCB tripping).
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The advantages are:
1. If you don't change the battery, it will still work, except during power failure.
2. The battery will probably last for the lifetime of the sensor anyway, despite the 12 month recommendation.
Christian.
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mike snipped-for-privacy@peppertree-broadcast.co.uk (Mike Hall) wrote in message

It looks a very useful unit, but how does it fit in with the usual advice that "smoke alarms should be kept at least 1 metre away from light fittings"? I've read this is smoke alarm instruction leaflets, but do not know the reasoning behind it.
Can you interconnect this device with other "normal" mains smoke alarms?
Cheers, David.
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"David Robinson" wrote | I have no intention of re wiring the lighting circuits (or | the kitchen), as they seem sound, and the installation was | professionally tested last year as being OK. The tests were | the resistance from live to neutral at 500V DC (greater than | 20M) and the fault impedance (something small and well within | limits - not sure between where and where it was tested | though). The wiring dates from the late 1970s (commenced 1978). | My question is: is it OK to simply replace the old fuse box with a new | consumer unit at this time? | I've read a few threads on here which seem to infer that you should | only replace the consumer unit if you have replaced everything else | downstream with latest regs compliant circuits. Is this true?
It doesn't have to comply with every detail of the latest regs but you're responsible for the safety of any wiring you connect. As well as insulation and earth testing (including testing RCD trip time/current) you should also check fundamental things like all SP switches are in the live wire, all ES lampholders have live to base stud and neutral to screw contact, polarity at sockets, and ring circuit continuity. I'm not sure when the regs changed to prohibit 2 single sockets on a spur, but that's something else to look out for. It might be as well to check that all earths have green/yellow sleeving and put red sleeving on the switched lives at lightswitches and lampholders, and make sure there aren't any bodges hidden anywhere.
Owain
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Not before 1981 as that's when 15th edition regs were published and 14th edition certainly allowed two singles on a spur. I've long since lost my 15th edition regs, and I can't remember what it said, nor if the info was normative or informative (it was in one of the Appendixs IIRC).
Actually, it's not against the 16th edition regs per se, it's in the OSG which is not part of the regs. However, you'd have to do some careful calculations to prove it was OK (clipped direct might just make it), but I haven't actually done the calcs. Whilst this might be an interesting academic excercise, it's not something I would contemplate doing even if the calcs came out OK.

--
Andrew Gabriel

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"Andrew Gabriel" wrote in message

Appendix 5 of the 15th ed. allowed only one single or one twin socket, just like the OSG now. This appendix was meant to be informative, although that was not always understood. This is why such material has been omitted from the 16th ed. and put into the guidance notes and OSG.
--
Andy



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Thanks for the replies Christian, Lurch, Owain and Andrew.

That's a helpful list - thanks.

There was one - it's gone now.

Earth sleeving is green only. All switched live returns are black only with no red sleeving. Easily sorted out.
I found one bodge/mistake in the cooker circuit added by the previous owner within the last three years (a nail through the cable!!!!!!!). I also found an interesting use of 3 core and earth: it takes both the switched live and the circuit live and neutral upstairs to the landing light. Might have to make this more conventional, though it cleverly saves at least 2m of cable!
I've already asked about and read about the smoke alarms and consumer unit choices, and am quite happy about those.
Thanks again for the help.
Cheers, David.
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broke, dont fix it. I wouldn't say that 3c+e is particularly interesting though, I see it every day in the back off the van, it doesn't do much for me! ;-)
SJW A.C.S. Ltd.
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