Central heating wiring shocker

[Alex Bird]

Hi, Ok, you've probably seen worse, but I'd appreciate opinions on this:

added the labels and red tags, and fixed the box to the wall)

This box is where the wires from fused CP, CH pump, room thermostat, timer and boiler meet.

Obvious flaws seem to be: The use of y/g wire for switched live. The timer says 3A fuse on it, no evidence of one. The terminal block doesn't look quite suitable for a pump rated at 39A

I've never touched CH wiring before, I was just checking it before I replaced the suppressor in the boiler, which I think has been f****n with my FM.

Cheers, Alex

[geoff]

In message , Alex Bird writes

39A ? - almost 9kW?

[Ian Stirling]

Might you be misreading 39W for 39A?

39A is a little heavy for most pumps, at least if your house is smaller than a power station.

[Set Square]

Indeed - if the pump truly takes 39A, it will heat the water sufficiently not to need a boiler!

[Jerry.]

What is more worrying to my mind is that someone can miss read such rating information, if a 39 A fuse / breaker had been fitted it would probably be more dangerous than any fault described above !...

[Alex Bird]

DOH! I've got a touch of the flu, it must have been sapping my brain already when I wrote that. Reflecting on it before I went to sleep, I did a little calculation...

It was actually 0.39. The label has a tiny dot and no leading zero. Surely there must be some regulations about poor labelling?

Anyway, does anyone have any thoughts on the actual wiring? Okay to wait until we renovate the area in the next six months, and fit a fused CP for the timer and replace the wires?

Cheers, Alex

[Set Square]

Well, it presumably *works*? It's potentially dangerous mainly to anyone other than you (or you, if you forget!) who may work on it and assume that (reasonably, though incorrectly) that green and yellow is earth when it is, in fact, switched live. The lack of proper fusing is also worrying.

In the short term, find out where it's powered from, and fit an FCU with a

3-amp fuse in it. [That is for the whole system, not just the programmer]. Then make sure that all exposed bits of green & yellow (where it connects to something) are clearly labelled. At your leisure, replace the cable with something more suitable. I suggest that, at the same time, you replace your choccy block connectors with a proper 10-way central heating wiring centre. They only cost a few quid. Connect it up in a way which is consistent with one of the plans in - depending on your system configuration.

[Ragnar]

Probably. Looks shoddy, but as long as you and all others who work on the system know about the abused yellow-greens it should be ok as a temporary solution.

greetinx Ranger

[Alex Bird]

Thankfully quite effective.

The FCU has a... 13-amp fuse in it. I'll change that.

Thanks for the other advice. We'll probably replace the box and wiring when the 70's wood effect panels come down. There's some brilliant wallpaper behind them, I never thought when I bought a digital camera that I'd use it for looking around corners ;o)

The suppressor seems to have stopped what became known as the 'fm fart', fingers crossed.

Alex