Given that on Xmas Eve was called out to yet another example of an electric shower isolator burning off it's neutral at the terminal, is it time to cease fitting isolators for the likes of ovens and showers?
Can we not just isolate in the consumer unit instead?
From what I have seen, there isn't an isolator of sufficient quality on today's market which is capable of carrying out it's function without burning out during normal service.
Compliments of the Season to one and all.
I've had a lot of experience with this, having worked for a Social Housing provider for a year. Yes, burnt out shower pull switches are common. I'd say 20+ per year in the area I worked in. That'd be around 4000 houses total, around 50% had electric showers, so the percentage is low, around 1%, but that is higher than I would expect.
At first, I put it down to poor installation when fitted, but that changed when I got called back, after 3 months, to one I had fitted. It was burnt at the neutral.I gave them a really good twist when tightening the screws, but subsequent experiments with a loose piece of 10mm T+E and a switch showed that the cable was twisting slightly when the plate was tightened to the box, and the cable was coming loose. The cables are so stiff that they cause the problem, in that it is difficult to tighten them enough to counteract the twisting/crushing motion when fixing it onto the backbox.
The switches with 2 screws on the terminals are far better. The round Cradtree ones are a better, slightly larger, unit, though cannot be used close to walls, so not suitable for many existing cables.
Cooker switches - very few of the wall mounted switches (40A+) ever got changed, Their internal profile makes them very similar to the 45A shower pull switches, but, I think the main point, they dont get turned on/off as much. The majority of shower switches were turned off when not in use.This adds in vibration each time the switch is used, so could add to the loosening.
Another accessory that was a regular 'burn out' was washer and dryer outlets. Usually an unswitched single socket outlet below the worktop. I almost always put this down to poor quality plug tops on the appliance. The Line feed would always burn, melting the plug top and ruining the socket outlet. Of course, the Tenants would always blame the socket, as their washer was only 6 months old!
I've had a lot of experience with this, having worked for a Social Housing provider for a year. Yes, burnt out shower pull switches are common. I'd say 20+ per year in the area I worked in. That'd be around 4000 houses total, around 50% had electric showers, so the percentage is low, around 1%, but that is higher than I would expect.
At first, I put it down to poor installation when fitted, but that changed when I got called back, after 3 months, to one I had fitted. It was burnt at the neutral.I gave them a really good twist when tightening the screws, but subsequent experiments with a loose piece of 10mm T+E and a switch showed that the cable was twisting slightly when the plate was tightened to the box, and the cable was coming loose. The cables are so stiff that they cause the problem, in that it is difficult to tighten them enough to counteract the twisting/crushing motion when fixing it onto the backbox.
The switches with 2 screws on the terminals are far better. The round Cradtree ones are a better, slightly larger, unit, though cannot be used close to walls, so not suitable for many existing cables.
Cooker switches - very few of the wall mounted switches (40A+) ever got changed, Their internal profile makes them very similar to the 45A shower pull switches, but, I think the main point, they dont get turned on/off as much. The majority of shower switches were turned off when not in use.This adds in vibration each time the switch is used, so could add to the loosening.
Another accessory that was a regular 'burn out' was washer and dryer outlets. Usually an unswitched single socket outlet below the worktop. I almost always put this down to poor quality plug tops on the appliance. The Line feed would always burn, melting the plug top and ruining the socket outlet. Of course, the Tenants would always blame the socket, as their washer was only 6 months old!
Usually an unswitched single socket outlet below the worktop. I almost always put this down to poor quality plug tops on the appliance. The Line feed would always burn, melting the plug top and ruining the socket outlet.
Definitely not a new thing with socket-outlets directly behind appliances (and hence I have none located there in my kitchen). I think in this case, if the appliance being pushed up against the back of the plug, there's not enough room for the heat that builds up in the fuse to escape, so this overheats the line pin in the plug, and/or the socket-outlet. (Neither the plug nor the socket-outlet are tested with an appliance butted up against the plug).
If my assertion as to overheating is correct, the "root cause" could be considered to be one of the following:
(I have not listed a problem with the tests in BS 1363 product standards, given that the appliance manufacturer's instructions noted in 1. is a valid argument for the product standard.)
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