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ccr32

Original Poster:

1,312 posts

98 months

[news] 
Friday 20th November 2009 quote quote all
Hi, hoping someone might be able to help me out - amateur DIY electrician alert...

My dippy girlfriend decided to take the immersion switch off the wall today without making a note of which cables go where on it, so now we are not sure how to put it all back together.

The switch is (if i've got this right) 2P 2T, in that there are 2x L's (live) and 2x N's (neutral), and 2 earths.

In terms of cables which are in the wall, there are 4 sets of red/black/earth ones. I know that one of these sets is the immersion, one is the water timer, and one is a socket which is a bit further along the wall, so the remaining cable must be the live from the fusebox/wherever.

My questions are therefore:
  • How do I identify the live/other cables?
  • How do I connect it all up?
I am thinking that the live cable, the socket and the timer are all put into one end of the switch (the bottom?), and the immersion is put in the top? Like this:

http://www.flickr.com/photos/44826221@N02/41187636...

I have a multimeter, but I'm a bit scared to use it on a 240v main to be honest. If I need to man up though, please, do let me know.

hidetheelephants

7,122 posts

73 months

[news] 
Friday 20th November 2009 quote quote all
To identify the supply, make sure the wire ends are well separated to avoid sparky unpleasantness, then switch on and make with the multimeter.

The diagram you've drawn shows what looks like a 2P1T switch, which is confusing to say the least; can you take a picture of the switch?

ETA man up you big girl's blouse.

Edited by hidetheelephants on Friday 20th November 01:15

maser_spyder

6,003 posts

62 months

[news] 
Friday 20th November 2009 quote quote all
Yup, man up, and get your meter on it!

Make sure it's set to AC voltage rather than DC, 600V.

Make sure wires are very firmly not anywhere near each other (for all 6!).

Turn on circuit at consumer unit.

Measure across black/red (or blue/brown) for voltage.

Turn off at consumer unit.

Connect input to input in pair, output to output in pair. The idea is that both live and neutral are both fully disconnected when the switch is 'off', hence the slightly more confusing type of switch.

Screw switch back to wall.

Connect G/F chain back to sink.


ALTERNATIVELY

The easier option is to use an electrical screwdriver (couple of quid in B&Q). Touch the top end with your finger, and touch the screwdriver tip on the live wire. The little light in the top of the screwdriver will light up if it's live.

First time you do this there's a bit of a dab dab dab when touching the top, but don't worry, it's perfectly safe.

Electrical screwdriver is easier as it leaves you a free hand to hold the insulation whilst prodding, whereas a multi-meter means you've got a probe in each hand and nothing to hold the wires steady when prodding.


If you're not 100% sure, just don't do it. Get help. No shame in it, so don't risk it unless you're absolutely certain you can do it safely yourself.

Eyes first and most, hands last and least.

maser_spyder

6,003 posts

62 months

[news] 
Friday 20th November 2009 quote quote all
Just looked at diagram.

Would make more sense for 'LIVE from fusebox' to be connected DIRECTLY (with terminal block) to 'timer' live, rather than all three connecting in one place.

What you've done there is connect all lives to the immersion, which will have switched on all the time.

Think of it;

Live to timer on constantly so that the timer has power to work - timer switches on and feeds immersion when calling for heat, so output from timer goes to live terminal of switch.

Does that make sense?

Ignore the socket for now, it's just going to confuse matters! You can just add this in afterwards to the 'LIVE from fusebox' once the rest is working.

Edit - have altered your little piccy;



It's hard to say for sure without knowing exactly what timer you have, etc.

Edited by maser_spyder on Friday 20th November 01:41

nonegreen

7,803 posts

150 months

[news] 
Friday 20th November 2009 quote quote all
surely the timer must be connected in series with the immersion. Your diagram seems to have it redundant. The double pole switch switches out both live and neural for complete isolation. depending on the age of the timer it may simply switch accross the live and must be between the main switch and immersion. Try checking continuety to socet, timer and immersion. Whats left must be live feed to switch. hth
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maser_spyder

6,003 posts

62 months

[news] 
Friday 20th November 2009 quote quote all
Just to confirm, your 'timer' should have two 'live' wires.

One for the timer feed, to give power to the timer to make it work.

One for the output, so it gives power out to the immersion.

The idea of the immersion switch is to fully isolate the immersion heater element in the instance of a malfunction. Hence the 2-pole thing where it isolates both neutral and live.

The switch itself (assuming you only have an immersion heater in the system?) should always normally be 'on', and only switched off to service the element.

If you have a normal gas boiler, the immersion switch would be used just when you need it (normally as a backup), but should still be connected to the timer, just isolated using the switch so it doesn't heat up when the timer calls for heat.

If it helps, ignore the switch, and think of it literally!

nonegreen

7,803 posts

150 months

[news] 
Friday 20th November 2009 quote quote all
maser_spyder said:
Just looked at diagram.

Would make more sense for 'LIVE from fusebox' to be connected DIRECTLY (with terminal block) to 'timer' live, rather than all three connecting in one place.

What you've done there is connect all lives to the immersion, which will have switched on all the time.

Think of it;

Live to timer on constantly so that the timer has power to work - timer switches on and feeds immersion when calling for heat, so output from timer goes to live terminal of switch.

Does that make sense?

Ignore the socket for now, it's just going to confuse matters! You can just add this in afterwards to the 'LIVE from fusebox' once the rest is working.

Edit - have altered your little piccy;



It's hard to say for sure without knowing exactly what timer you have, etc.

Edited by maser_spyder on Friday 20th November 01:41
Nope the timer must be in between the switched supply and the immersion if you feed the switch from it there is no proper isolation. IMO of course

maser_spyder

6,003 posts

62 months

[news] 
Friday 20th November 2009 quote quote all
nonegreen said:
maser_spyder said:
Just looked at diagram.

Would make more sense for 'LIVE from fusebox' to be connected DIRECTLY (with terminal block) to 'timer' live, rather than all three connecting in one place.

What you've done there is connect all lives to the immersion, which will have switched on all the time.

Think of it;

Live to timer on constantly so that the timer has power to work - timer switches on and feeds immersion when calling for heat, so output from timer goes to live terminal of switch.

Does that make sense?

Ignore the socket for now, it's just going to confuse matters! You can just add this in afterwards to the 'LIVE from fusebox' once the rest is working.

Edit - have altered your little piccy;



It's hard to say for sure without knowing exactly what timer you have, etc.

Edited by maser_spyder on Friday 20th November 01:41
Nope the timer must be in between the switched supply and the immersion if you feed the switch from it there is no proper isolation. IMO of course
You're quite right, but that way would isolate the entire timer with the immersion switch 'off'.

If there is a gas boiler on the system as well as the immersion, this wouldn't work, as the immersion would HAVE to be used at all times, in order for the timer to stay powered.

OP - do you have a gas boiler as well as immersion? Or just immersion?

If just immersion, I'll adjust diagram to suit.... See below;


ccr32

Original Poster:

1,312 posts

98 months

[news] 
Friday 20th November 2009 quote quote all
Thanks for the help so far people - in reading some of the posts, it doesn't sound like I've been too clear with the set up.

The CH/HW is gas fired, and run off the timer. The immersion is simply there as a backup, for when you want HW without firing up the boiler. The heating/timer does not normally use the immersion.

So, when it was all working before:
  • Timer was always live - i.e. it had power to turn off and on as it pleased
  • Socket was always live
  • Immersion (independant of timer/CH) was only activated when switched on by this switch.
The G/F (who I have since unchained from the sink again) is going to take some pics this morning and I'll put them up on here to hopefully make things a bit clearer.

Thanks again.

ccr32

Original Poster:

1,312 posts

98 months

[news] 
Friday 20th November 2009 quote quote all

maser_spyder

6,003 posts

62 months

[news] 
Friday 20th November 2009 quote quote all
ccr32 said:
Thanks for the help so far people - in reading some of the posts, it doesn't sound like I've been too clear with the set up.

The CH/HW is gas fired, and run off the timer. The immersion is simply there as a backup, for when you want HW without firing up the boiler. The heating/timer does not normally use the immersion.

So, when it was all working before:
  • Timer was always live - i.e. it had power to turn off and on as it pleased
  • Socket was always live
  • Immersion (independant of timer/CH) was only activated when switched on by this switch.
The G/F (who I have since unchained from the sink again) is going to take some pics this morning and I'll put them up on here to hopefully make things a bit clearer.

Thanks again.
Understood.

Your first piccy is entirely correct then.

There's a permanent feed to the socket and timer, which aren't activated by the switch.

All the switch does it activate the immersion heater, which is manual on/off.

After all that, looks like you got it spot on first time!

Good luck, and be careful!

Ganglandboss

6,983 posts

83 months

[news] 
Friday 20th November 2009 quote quote all
ccr32 said:
If I need to man up though, please, do let me know.
Not at all - you need to leave it be and get a spark in. If you don't know what you are doing, you shouldn't be touching it.

homeimprovements

121 posts

55 months

[news] 
Friday 20th November 2009 quote quote all
totally agree wirth gangland boss. Only today was I at a house today doing a consumer unit change as the old re-wireable one needed replacing due to a extension we have nearly finished. I commented to the customer that they had been lucky the fuse for the shower hadnt been tripping as it was far to small and they said that it used to trip all the time so he got a piece of 2.5mm earth and used it as the fuse wire.

When i explained to him that he could so easily have killed his wife and kids to his stupidity I think he realised the error of his ways. Even more so when we tested the cable for the shower and it was showing serious signs of overheating

What i am trying to say is get a pro in as what looks to be a simple case of put this wire here and that wire here could easily end up in tears especially if you have a old style fuse board as i expect you probally have


Deva Link

26,934 posts

125 months

[news] 
Friday 20th November 2009 quote quote all
Is "timer" really the central heating timer?

The whole thing is very dodgy anyway - the immersion heater switch is being used as a junction box. Does it have it's own fuse/MCB? If so, there shouldn't be a socket on the circuit.

I don't do domestic stuff very often but isn't the wiring suggested for the switch upside down (not that it would really matter)?

andy43

3,343 posts

134 months

[news] 
Saturday 21st November 2009 quote quote all
As above - it looks wrong from here.
You've got a 3 kw immersion AND a socket running off either a ring main or a single feed of presumably 2.5mm cable - can't tell from the pics where the 'socket' cable continues to - could be either part of a ring (immersion shouldn't be on that), or a spurred socket off the immersion feed (socket shouldn't be on that).
Either way, it's not right, but would work apart from undersized cabling and suspect fuse rating. Wouldn't want to be boiling a kettle and running the immersion off that socket at the same time though.
And then there's a central heating timer off the same cable? - that should have a separate fused switch (similar to your shiny chrome one but with a fuseholder on the front). If it hasn't got a fuse further along, its got the chance to get either 13 or 30 amps stuck up it if something goes wrong, which isn't good.
I'm firmly in the DIY 'do the research and give it a go' camp, but given the advice requested, I think an electromagician is needed to check it over.

Edited by andy43 on Saturday 21st November 14:08

miniman

16,659 posts

142 months

[news] 
Saturday 21st November 2009 quote quote all
ccr32 said:
I presume you have identified the main feed from the fusebox now? As far as I can see it is the one with the green/yellow sheathed earth wire. How far away is the socket you refer to? If it is quite close, you can use the continuity tester on your multimeter to figure out which cable supplies it. From there it's just the heating timer left.

Looking at the cables, the only possible way I can see to connect them up is the cable coming from the top of the back box goes to one set of terminals on the switch, everything else goes to the other terminals (i.e. reds together, blacks together, greens together). The timer doesn't control the immersion, does it?

ccr32

Original Poster:

1,312 posts

98 months

[news] 
Sunday 22nd November 2009 quote quote all
All sorted now - to my amazement, the girlfriend actually put it all back together herself using the advice on here before I got a chance to..!

With regard to some of the concerns, I do agree that it seems a bit dodgy to have all that running off one socket. However, a bit of further routing around the airing cupboard reveals a couple of additional fuse box things which then run to the timer and the immersion.

All working ok now so will leave it at that, and i'm happy that there are enough fuses in there not to worry me about something bad happening. Though I will bear in mind what has been said about running a kettle at the same time as the immersion..!

Thanks for your help.
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