Just in the dying weeks of our extension build and the plumber is fitting his electrical bits. He's about to bury the 5 core *flex* (not solid core cable) for the thermostat in the wall plaster, but I've got in mind that this is a no-no. However, having thought that thought I can't find any reference to it being prohibited in the 16th edition on site guide. Anyone with any references as to why that is not acceptable?
I'm curious about the five cores. Ignoring earth, most older stats need only three - newer ones like programmable ones two. Unless it needs both heating and cooling outputs. So the common cable to use is triple and earth.
My programmable stat (not battery powered) has
earth neutral live switched live for h/w switched live for c/h
Perhaps it's a wireless thermostat like the Honeywell HC60NG which would need at least 4 cores, a L & N for the electronics and a pair for the boiler thermostat circuit. Add in a (redundant) CPC and you've got 5 cores or a T&E and a twin.
-- Mike Clarke
You tell us why it is wrong, it's easier that way. You must know why it could be wrong if you are going to challenge a profesional with comments made by people you don't know in a newsgroup! I ued to hate working for people like you, the classic Victor Meldrew with the "readers digest book of how to rewire". How do you know the suggestions will be correct? Are you seriously going to say to the electrician that people in a newsgroup said he was wrong? You're going to look an even bigger tit than you appear now.
Using flex for permanent wiring is acceptable. It's not normally done because it's significantly more expensive. Wiring terminals need to be suitable for flex strands too.
Unless it has earthed metalic protection, the circuit must be RCD protected accroding to 17th Edition regs if buried in a wall. (This is nothing to do with using flex or solid core.)
Personally, I wouldn't want to have the heating system sharing an RCD with anything else (might lose your frost protection whilst away on holiday), so you might consider burying a steel conduit or steel capping in the wall (and earth it) rather than have the central heating on a dedicated RCD.
On Sat, 25 Oct 2008 01:07:27 -0700 (PDT) someone who may be pepper wrote this:-
You need to follow the 17th Edition now. This has new requirements about burying cables. I think they are over the top, but in their wisdom that is what IET have concocted.
Flexible cables can be used in fixed wiring. The usual drawings one may see in books show examples of this, for example using a short length of high temperature flex to feed a luminaire. However, it must be secured properly (as indeed must any other type of cable).
The plumber will also need to ensure that the flex is appropriately fused. That may mean inserting a fuse into the circuit, depending on circumstances.
Why has the room stat got connections for water heating?
Because it's a programmable stat, that acts as the timer for the whole system.
Do you have the above phrase on a keyboard shortcut or something?
I would love to know how many times I have been saved from either being taken to the cleaners by so-called professionals, or at least saved bucket-loads of cash which would otherwise have been paid unnecessarily to tradesmen, courtesy of advice generously proffered by people in newsgroups (especially this one) who I've never met.
As a real professional, you of course would never dream of taking any slightly dodgy shortcuts to get a job done quicker/easier - however, are you really going to tell me that in your everyday work you've never, ever come across the crappy results of cowboy tradesmen who *have* done so?
David
That is a nice piece of kit. I have fitted hundreds of stat, programmers and programmable thermostats but I have never seen that model before.
Not a bad price as well.
Adam
Not much of a wireless system then :-)
Adam
I bought a house some years ago with PVC covered cable buried in the plaster (Ceiling) The plaster cracked along the line of the cable run and no matter how hard I tried to keep the crack filled it kept re-appearing. Must have been something to with differential expansion. FWIW
The only feature I wish it has is "+1 hour" for the h/w, you can turn it on, but then it stays on until the next switching period, not too bad provided the tank is well insulated and has its own stat.
If the wiring control centre is in the airing cupboard you could put seperate 1 hour booster switch in the cupboard.
Adam
The wiring centre is in the kitchen with the boiler, but yes, I realise I could put one in parallel.
OK, perhaps I should have said "like the Honeywell HC60NG receiver box used in conjunction with a CM927 or similar wireless room thermostat" :-)
do you have to be such an arse I would hate you to work for me, if you have f*ck all to say why waste the bandwidth, just because the guys a plumber does not make him an electrician he might not be qualified to do either job and could be just a flipping cowboy they do exist!!!!!
Ian; I'm the OP - I am am a seasoned newsgroup user, and am well aware of the range of good and bad advice that can originate on the net. I know that very very much of the advice in this particular group is valuable and informed, and that professionals do frequent this group too. You will note that in my original post I asked has "anyone any
*references* as to why that is not acceptable?"... thus if it had been unlawful then someone could have said 'no this is specifically prohibited in paragraph x section y of the 17th edition'. With that information I could have gone back and told my plumber that I wasn't happy with what he was installing. As it is, I have asked the question of the group, I have the concensus that it is fine and I have not done a Victor Meldrew on the tradesmen working for me. Don't berate me for asking, as David (Lobster), said there are *plenty* of cowboy tradesmen out there who do cut corners. NB. FYI Dave Plowman - It is a Heatmiser PRT, I think the five cores are LNE and a changeover contact i.e either of the remaining two terminals are energised. Thank you everyone for your helpful replies.
Despite my not having read the 17th edition regs.... I'd be happy provided it was in a plastic conduit or trunking under the plaster.
It looks a very nice thermostat and simple to use. I can understand how to operate it just by looking at the picture.
Tony
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