Thanks Andrew. I will fit a 20 amp switch with flex outlet. I will also replace the flex with butyl.
As the fused spur that failed was the second one to fail, I assume they are not really suited to such a heavy long term load.
Further thought here -- If the terminal is vastly larger than the bundle of strands (which it probably is), strip enough to fold them over two or more times so they occupy a good proportion of the terminal, and aren't able to be pushed out of the way by the terminal screw.
As someone else said, avoid mixing different sized strands from different conductors in the same terminal -- that's very difficult to do well, particularly when they're very different, such as a 2.5mm sold core and a bundle of fine flex strands.
Last time I did this, I used one of these:
Thanks all - I bought one of these:
Also bought a metre of butyl flex to connect to the heater.
The message from Rumble contains these words:
Aluminium behaves in the same way. Aluminium (or as they would have it, aluminum, cable was the result of many fires in North America when it was used as a substitute for copper in wiring domestic receptacles (sockets to you). Under the pressure of the terminations designed for copper the aluminium migrated away from the joint which then became high resistance and heated even more than is normal for the average NEMA 5-15 and ..................
That's interesting. I've just swapped out my heating pump, and as the existing cable was a bit short - got in the way of the washing in the airing cupboard - used a bit of PVC cable I had lying around. Should I swap it? Pumps do get a bit warm!
Andy
Oh dear, no...
Also note that the 17th Edition will _explicitly_ban_ soldering or tinning of stranded conductors in screw terminals [Reg.526.8.2 in the DPC] and in any type of terminal where there is relative movement between the soldered and non soldered parts of the conductor [526.8.3].
On a related matter it also bans putting fine strands into terminals not specifically designed for them, unless the ends are suitably treated. Stock up on the bootlace ferrules now.
I'm surprised this was a common enough practice to have been worth commenting on. Soldering is a skill which I've not noticed your average electrician has in the first place. The days of appliances being supplied with pre-tinned leads (which was for rapid testing on production lines, and not as many though a convenience for wiring on a plug or whatever) has long since pasted.
The short precut lengths for immersion heaters jolly well ought to come with prepared ends including ferrules, for the price they charge...
Yes :-)
Going back to thermostats for a moment, how is the 'new' requirement for an overheat 'stat actually implemented? I've not had to replace one since this change came in. Does an immersion thermostat (as the loose item which drops into the tube in the heater body) now contain two thermostats, or is the backup 'stat built into the heater boss, or what exactly?
A picture I saw made it appear to be built onto the live terminal post.
The former, in my case.
On Wed, 09 Jan 2008 20:32:36 +0000 someone who may be Andy Champ wrote this:-
The instructions for the pump (many of these are available on-line) will undoubtedly say to use at least 85C flex for the connection to the pump.
Aluminium has other problems too. It forms a thin surface oxide layer on exposure to air which is extremely hard (it's used to make sandpaper and other abrasive products), and a very good insulator. This also leads to poor contacts if not well made in the first place.
It can also burn nicely -- we use it in fireworks...
OK thanks.
The pump was free (off freecycle) and I don't have any instructions! I can't find them either (except one that tells me to install it with the shaft horizontal - which it is!)
If you could point me at some instructions I'd be grateful.
Andy
In a recent one I've replaced there are two thermostat (n/c switches?) the Line wire is connected in series with these thermostats to the heating element .The 'normal' temperature selecting thermostat is the second one after the non-adjustable 'overheat' thermostat.
On Thu, 10 Jan 2008 21:03:31 +0000 someone who may be Andy Champ wrote this:-
To find them on-line I would use a search engine to find the web site of a large manufacturer, such as Grundfoss and look for a similar pump. The names of other manufacturers can be found by looking up an on-line shop, like Screwfix, which sometimes contain links to the instructions for the pumps they sell.
I suspect you could do this just as well as I could.
Sounds interesting, can anyone email or post a snippet of the draft that covers this?
cheers, Pete.
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