Re: Gas Central Heating Power

What's wrong with doing it via a plug+socket (assuming its suitably fused)? The only issue I can see is that its a fixed installation, and therefore maybe better suited to being a FCU - but I think making it unacceptable is a little strong.

Incidentally, my parent's old programmer died years ago (the mechanical clock itself died) so they just now use a plug-in timer with the boiler plugged into that! Worked fine for the last 15 years or so they've been doing it. Had the boiler replaced in about 1999 or so also and it was also wired up the same way (kept the dead programmer and used the plug-in timer).

I presume the heating engineer was referring to requiring a method of isolating the system for maintenance.

I can't think why a socket can't be used if it is replaced by an unswitched one, or one with double pole contacts. A 20 year old socket is extremely unlikely to be DP already, but replacements can be obtained for pennies. Mark the replaced socket with a label "Double Pole Isolator" to reassure engineers, who will probably pull the plug out anyway!

Ensure there are no other means for mains electricity to enter the heating system. It is not unknown for the boiler and pump to have a different supply than the programmer, and then have the circuits mingle without a single point of isolation.

Christian.

That wouldn't work under current building regulations. Water and heating have to be separately controlled nowadays.

Christian.

AFAIK a 13A socket is OK as long as it is unswitched. "The method of connection to the mains electricity supply must allow for complete isolation from the supply. The preferred method is by using a fused, double pole switch with a separation contact of at least 3mm. The switch must only supply the appliance and it corresponding controls, i.e. time clock, room thermostat, etc. Alternatively an un-switched shuttered socket outlet with a fused 3-pin plug complying with BS 1363 is acceptable"

This is all to do with Electricity at work regs. Essentially to do maintenance (on any fixed peice of machinery AFAIK) you must be able to isolate both/all supply wires.

This can be acheived with a FCU (3A fuse). 13A plug with 3A fuse in unswitched socket. 13A plug with 3A fuse in double-pole switched socket.

Being self-employed I don't have to follow this crap and I open boilers with the power on which is really helpful for diagnosing faults . But I always but a voltage probe on _any_ terminal on any connected fitting before undoing it - just in case - about once a year it'll save me a shock.

British Gas in the south about 20-25 years ago insisted on a switch socket and plug to enable total electrical disconnection, whereas the north of England would accept a double pole fused spur.

If it was wired that way then it was a cowboy job. The only instance I can think of where the supplies are separate is where a Myson convector heater would have its own independent supply. It switches on the fan via pipe thermostat.

Vaillant in their boiler installation instructions recommend using a plug and an unswitched socket.

Geoff

It wasn't given as an example of best practice!

Christian.