I have three Contactum CUs (bought in the last two or three years from TLC), they're in a boat so quite damp conditions. They all look perfect so far. ... oh, they're painted metal ones, that was the point!
Presumably the DIN-rail mounted main switch and RCD/MCB/MCBO will continue to have plastic construction, surely they are in closer contact with any faulty overheating connection?
May well count as prevention of a building fire to the fire service ...
Even more reason not to have an external box, then. It's trivial to submit the reading yourself these days anyway.
I've certainly seen newish houses where the CU is external to the house.
I thought the existing Wiring Regulations required all connections / live parts to be in an incombustible enclosure?
Therefore the common brands of CU which are combustible are simply not fit for the purpose and are returnable to the retailer under Sale of Goods Act.
Owain
The other option for TT systems was to provide extra sturdy insulation around the feed on entry and inside the CU before it becomes RCD-protected, and kits were available to do this for some metalic cased CU's.
I don't know what Ammendment 3 will say on this topic.
The rise in dirt-cheap CU's is something that's happened mainly in the last 10 years, so I suspect the proportion of houses with them has grown dramatically - both new houses and rewires.
And, of course, Part P of the building regulations and the '5 week wonders' with a 'Part P qualification'
Owain
I had nothing else but painted metal enclosures in my factories, from the distribution board to individual isolating switch fuses. Over several decades, they managed to survive an industrial environment very well without needing any maintenance to the cases.
Simply because having the *potential* of a ignition source under the (in most cases flammable) only escape route is stupid. It's just fortunate that such fires are thankfully rare.
Equally I don't like the 30's semis that have the cooker directly under the stairs, either.
Makes me feel glad I chose a metal Hager.
But the more pertinent question is:
Why 5x in the last 5 years?
Poor quality devices? Terminals?
The damn things should not be getting hot on a regular basis in the first place.
Andrew Gabriel wrote
I had my lecci meter changed today. The electrician had come from a house where he he'd refused to change the meter. He'd looked at the circuits connected to it and discovered the T&E were lead sheathed. It appeared much of the house was the same.
When we moved into this house (1977) there was still some lead sheathed lighting cabling. The insulation had statrted to go, since the outer was live!
Why not? It's recommended for electrical contacts.
Lead shielded cable has/had no earth wire. So obviously didn't knowwhat he was talking about. And might conceivably have been servicable.
Or a drop in the quality of the terminals.
There is a thread on the IET forums about this - a lot of folk are citing poor terminal quality (dissimilar metals and poorly constructed cage clamps that make it too easy to get the wire or busbar prong the wrong side of the cage).
I am less than happy with the quality of many accessories. You get screws where the earth in a bit of 2.5mm2 disappears up the side of the screw no matter how you arrange it. Or weak and flimsy terminals.
I've had heaters and extension leads where the moulded plug runs hot under full load (hot not warm) - a problem which seems to miraculously go away when I rip the plug off and replace with a nice solid MK one.
I have only had one socket do that (all GET plastic sockets here, new 3 years ago) - and that had been abused because someone failed to plug a heater in properly with the plug half out).
So to me it suggests that there's too much crap entering the market. Other than gratuitously poor installation or extreme abuse or exceptional failure, no switching device or accessory should be getting hot let alone catching fire.
Whilst I don't think thermoplastic CUs are a great idea, they are solving the wrong problem.
Higher product standards and random sample testing on an ongoing basis is what's needed.
The propellant is flamable.
The product is, but the propellant is actually CO2.
In message , charles writes
In our old house we had one length of lead sheathed cable IIRC under the floor.. Removed when I rewired the kitchen IIRC. It was ok, but the rubber insulation would have been dodgy once moved.
More worrying was the lighting wiring. It still had the original 1930's wiring - rubber sheathed singles in narrow metal conduit. In the loft I found choc blocks where more modern additions had been made. The choc blocks where not in nay enclosure, or even wrapped in tape. In one the cable had become loose, and I found it happily sparking away. Felt quite lucky not to have had a fire.
It will give surveyors and electricians another thing to put in their survey reports though.
I wouldn't be surprised if has quite a rapid impact, because electricians seem quite keen in my experience to replace CUs with ones conforming to the latest standards.
Hadn't used to be. I left a car at Heysham docks for week when I went to MGP. It was subjected to a gale and parked facing into it. Took a 1 mile tow to get it going, badly. I popped the bonnet, mate jumped out, sprayed WD40 on the external sparks. It lit up very well. I got a really good look at his startled face though the gap between scuttle and bonnet.
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