central heating controls and immersion heater wiring question

[x4cs]

The inlaws have had british gas round to install one of their wireless thermostat and a UP2 duel channel programmer for controlling the hot water and heating, and here in lays a potential problem.

Their fuse board is an old wylex job with 3036 semi enclosed ceramic rewirable fuses and lately their lighting circuit has blown 4 times since the british gas kit was installed in September 2012. Prior to that, they've never had an issue with fuses blowing so often and theyve lived in the house for 30 years.

Said fuse went again today and in the process of rewiring it, I noticed that there was no power to any of the british gas kit or their immersion heater - the inlaws hadnt noticed this before......It transpires that the kit and the immersion heater is running off a 5A lighting circuit.

Ive had a look round the house and when they have their 'typical' lights on around the home, they're drawing around 3/3.5 amps before other lights get switched on and of course thats excluding the immersion heater....it appears that theyre quite probably oveloading the circuit...

That said, I've not been house bashing for a number of years, and I don't have my books to hand, however I'm almost certain that the immersion heater should be on its own 15A circuit - can someone confirm that for me? and considering the house was wired circa 1970, id imagine that when the immersion heater went in, it was wired off a ring....How its ended up on the lighting circuit, I dont know - I can only think that whoever installed it had done it.....my suspicions are seconded by there being no immersion heater circuit in the box......thankfully the cooker and shower have their own circuits!


My second question is regarding the british gas kit - does anyone have any experience of it and more importantly, although the paperwork suggests it should be fused at 3A, should whoever wired it have taken a feed off the ring main as a pose to the lighting circuit? I don't know what their routine procedure is for such equipment.

Im making the assumption (I shouldn't assume I know) that someone should of had the foresight to take a look at the fuse board, recognise the age/restrictions of it and do some calcs to see whether it would be wise to wire it off the lighting circuit....


Thanks in advance for all replies.

 

[telectrix]

call the xperts, bodgit gas. ha,ha. ideally the FCU should be off the ring, as you say. and imm. heater on it's own circuit, 15A fuse or 16A MCB.

 

[R G]

Get B G back , immersion and c/h should not be on lighting circuit , check to see what certification has been left . caeey out a full test on the wiring to see if it needs re wiring , it may be o/k , just requiring a new consumer unit and bonding together with minor improvments

 

[x4cs]

Get B G back , immersion and c/h should not be on lighting circuit , check to see what certification has been left . caeey out a full test on the wiring to see if it needs re wiring , it may be o/k , just requiring a new consumer unit and bonding together with minor improvments

Cheers Ray. There is some BG paperwork relating to safety checks, but its their own paperwork - its never remotely seen an electrical test certificate. Ive plans to test the wiring myself. Im expecting it to be ok considering the lack of problems they've had with the electrics over time however I've already advised that a new fuse board and some remedial bonding works are a bordering on essential so that'll be getting done as soon as. If the testing throws up anything else it'll be a rewire.

As for the heating controls, the mother in law is going to phone BG in the morning and ask for them to re attend.....for what its worth, looking at the paperwork they left, it looks like it was a subbie that came and did the job as a pose to a pay rolled BG engineer.

 

[Octopus]

Why can't the ch controller be on the lighting circuit?

 

[snowhead]

The BG kit can't be supplying and controlling an immersion heater from the 5amp supply, it may be controlling only, the fuse would have blown instantly, not 3 or 4 times in a few months.

I assume they have a gas boiler and the 2 channel BG programmer is contolling the heating and water supplied by that?

 

[onions1066]

Why can't the ch controller be on the lighting circuit?

My thoughts exactly nothing wrong with that. What's the difference to wiring off the ring then fusing down, nothing at all

 

[R G]

I take it you lads are serious , would you have it , where the c/h supply is of the lights .

 

[Octopus]

I take it you lads are serious , would you have it , where the c/h supply is of the lights .

Why not? Sometimes its the only way.

 

[FrankUK]

Assuming that the Immersion is rated at 3kW, how could it possibly work from a 6A lighting circuit, along side the lights, without taking the rewireable fuse out?

 

[pencilpusher]

The controller being on the lighting circuit NOT the immersion.

 

[onions1066]

I take it you lads are serious , would you have it , where the c/h supply is of the lights .

Ok so you have a boiler upstairs and all wood floors upstairs so no way to get to a socket and you have feed at the pendant what would you do

 

[x4cs]

The BG kit can't be supplying and controlling an immersion heater from the 5amp supply, it may be controlling only, the fuse would have blown instantly, not 3 or 4 times in a few months.

I assume they have a gas boiler and the 2 channel BG programmer is contolling the heating and water supplied by that?

You're right, Its not supplying, its just controlling - sorry if i didnt make myself clear first time around. You also assume correctly regarding the boiler and 2 ch BG programmer. The reason why I questioned the circuit is because its quite obvious when you enter the house that there are a lot of bulbs, drawing X amount of wattage each and after a quick rekkie and calculation, it suggests that lighting in the house could be drawing around 3-3.5 amps during typical usage. Considering that and the draw on the controller being 3A, according to its paperwork, I would have been inclined to put it on a fused spur and taken the feed off the ring main. Am I being unnecessarily cautious?

 

[FrankUK]

The controller being on the lighting circuit NOT the immersion.

"Said fuse went again today and in the process of rewiring it, I noticed that there was no power to any of the british gas kit or their immersion heater - the inlaws hadnt noticed this before......It transpires that the kit and the immersion heater is running off a 5A lighting circuit."

 

[onions1066]

Yes the boiler will not draw 3 amps, put a clamp meter on it you'll be lucky if its drawing an amp

 

[pencilpusher]

"Said fuse went again today and in the process of rewiring it, I noticed that there was no power to any of the british gas kit or their immersion heater - the inlaws hadnt noticed this before......It transpires that the kit and the immersion heater is running off a 5A lighting circuit."

He seems to have cleared this up!

 

[telectrix]

sounds like the C/H controller is the problem, overloading the lighting circuit when lights are on. as said before, immersion heater would blow a 5A fuse pretty rapid. good job they not a farmer or a nail would have replaced the fuse the first time it went.

 

[x4cs]

The controller being on the lighting circuit NOT the immersion.

When the lighting circuit fuse is removed, there is no power what so ever to the immersion and Ive not had a go at trying to fathom why, but it stands to reason that some, if not all of its power is being drawn from the lighting circuit.I don't know the details of the immersion, Ie its power, I only know that, according to the occupants, its the same one thats been in since they moved in, around 30 years ago. I only became privy to this issue a matter of hours ago and wanted some second opinions.

 

[R G]

I can assume that the central heating is the primary source of heating and hot water and the immersion heater is there as a back up , so if the 5amp fusewire is blowing when the lights and c/h ssystem is in use then there is an overload , meaning the c/h system needs to be on its own circuit , to put it bluntly if B G put the system in its their responsibility to put in the correct circuits regardless of solid wood floors and the difficulties , after all they would have had to do find a supply for the immersion heater circuit

 

[x4cs]

I can assume that the central heating is the primary source of heating and hot water and the immersion heater is there as a back up , so if the 5amp fusewire is blowing when the lights and c/h ssystem is in use then there is an overload , meaning the c/h system needs to be on its own circuit , to put it bluntly if B G put the system in its their responsibility to put in the correct circuits regardless of solid wood floors and the difficulties , after all they would have had to do find a supply for the immersion heater circuit

Makes sense to me. There is an accessible socket considerably closer to where the dam thing is mounted than any live feed from the lighting, and unless they know something I don't, it would have been 'easier' to take the feed off.


Anyway, thanks to all for the feedback