Immersion Timer - B&Q GreenBrook

too_sleepy

Hi

The solution to this is probably very obvious to those in the know, I'm deffo not in the know.

Wanting to install a timer on my immersion I bought a Greenbrook T23HA-C immersion timer from B&Q. Product Manual: http://www.greenbrook.co.uk/pdf/T23HA-C.pdf

The timer has connection for Live, Neutral and Earth (from mains and to appliance).

I planned on placing the timer between my original immersion switch and the boiler. My immerison switch has an on/off switch and a shower/bath switch.

My plans were scuppered when I discovered the cable from the switch to the boiler had 4 wires, red (live), green/yellow (earth), black and blue.

After much head scratching I figure the black and blue wires must carry a signal for bath/shower ??? One for each, is this correct?
If this is the case could I wire the timer with the live and earth and leave these two wires going directly to the boiler. The main switch controls both/sink as before and the timer controls the on/off for the immersion???

Any advice greatly appreciated. I'm telling myself to get an electrician in.

Thanks

Hoagy

Good choice of time switch, by the way.
The time switch must go upstream of the sink/bath switch.
You need to turn off the power, disconnect the incoming cable from the switch, connect it to the timer and put a new short piece of cable from the timer to the switch.
If you are not confident doing that, then you do need to get an electrician in.

RoundyMooney

too_sleepy wrote:

Hi...

I planned on placing the timer between my original immersion switch and the boiler. My immerison switch has an on/off switch and a shower/bath switch.

No. Aside from the twin switched feeds you discovered, the timer itself needs a continuous 24 hour supply. Otherwise how can the clock operate? Theoretically, a fused outlet should be used first, then timer, then immersion switch. This is an unnecessary complication IMHO, once your immersion is protected by an RCD.

too_sleepy wrote:

My plans were scuppered when I discovered the cable from the switch to the boiler had 4 wires, red (live), green/yellow (earth), black and blue.

It is actually red to bath element, black to sink/shower, blue neutral etc. This doesn't matter in any event, provided you leave it the way you found it.

Switch off power, and verify. Take incomer to immersion switch, and feed to your timer. Procure some 3x2.5 sq. heat resistant flex, and run this from output of timer to supply/mains side of switch. Easy peasy.

Check that all your connections are good and tight when you're finished.

too_sleepy wrote:

Any advice greatly appreciated. I'm telling myself to get an electrician in.

Thanks

Not necessary once you take your time and work safely.

too_sleepy

Thanks for the advice.
I'm getting a clear picture now.

One other problem I have is that the cables running to the immersion switch are burried behind the wall, I have access to the cables running from the switch to the immersion, that's why I was so keen on placing the timer that side of the switch.

The timer has an internal battery that will last for hundreds of hours, I'll live with changing the battery once a year to save me from hammering holes in my wall.

I don't mean to dismiss the advice I'm getting, I just want to check one other option, fitting the timer after the switch and run the red and black wires to bypass the switch. The blue and earth going through the timer.
I just don't understand the logic of the wires, which one carries the on/off signal?
Maybe I could just bypass the bath/red wire as I don't really need to time this one: and run the sink and other wires through the switch.

I'm confusing myself now.

Thansk in advance for any more advice on this.

too_sleepy

Thanks for the advice.
I'm getting a clear picture now.

One other problem I have is that the cables running to the immersion switch are burried behind the wall, I have access to the cables running from the switch to the immersion, that's why I was so keen on placing the timer that side of the switch.

The timer has an internal battery that will last for hundreds of hours, I'll live with changing the battery once a year to save me from hammering holes in my wall.

I don't mean to dismiss the advice I'm getting, I just want to check one other option, fitting the timer after the switch and run the red and black wires to bypass the switch. The blue and earth going through the timer.
I just don't understand the logic of the wires, which one carries the on/off signal?
Maybe I could just bypass the bath/red wire as I don't really need to time this one: and run the sink and other wires through the switch.

I'm confusing myself now.

Thansk in advance for any more advice on this.

air

There isnt actually any "signal" on those wires, they are live load carrying cables.
What you have in your 4 wires is an earth (green/yellow), a neutral (blue) and essentially 2 individual live feeds to each of the elements (red -> bath element & black -> shower element) as Roundy has explained.
Your existing setup isnt as intelligent as you think, its a simple system where the live is split and fed to two independent elements.

RoundyMooney

too_sleepy wrote:

Thanks for the advice.
I'm getting a clear picture now.

One other problem I have is that the cables running to the immersion switch are burried behind the wall, I have access to the cables running from the switch to the immersion, that's why I was so keen on placing the timer that side of the switch.

The timer has an internal battery that will last for hundreds of hours, I'll live with changing the battery once a year to save me from hammering holes in my wall.

I don't mean to dismiss the advice I'm getting, I just want to check one other option, fitting the timer after the switch and run the red and black wires to bypass the switch. The blue and earth going through the timer.
I just don't understand the logic of the wires, which one carries the on/off signal?
Maybe I could just bypass the bath/red wire as I don't really need to time this one: and run the sink and other wires through the switch.

I'm confusing myself now.

Thansk in advance for any more advice on this.

Alright, you're talking about signal on a 230 volt cable...

You're also talking about in effect breaking your neutral (through a de-energised timer). Any electrician will tell you that that is one of the most dangerous occurences possible in a domestic wiring set up.

How do you think the back up cell in the timer charges in the first instance? Nevertheless, it will not last hundreds of hours as you suspect.

Take either my advice, and do it the way instructed; or your own, that is to call an electrician. I don't think there is a safer way tbh.

One parting thought, electricity and water do not mix well. People, and incorrectly connected immersible elements, say without earths and neutrals, fare even worse.

Woddle

Its very simple, turn off power to your immersion switch,locate the live, neutral and earth that supplies your immersion switch, once done take it out of your immersion switch and let it feed your new timer switch, now out of your load side of your timer switch let it feed your old immersion switch. once all this is done, leave your old immersion switch in the on position, and set your times with your new timer switch, do not worry that your immersion switch is left on, as there is no 230 volts going to it, until your selected time comes around.

Beach Head

Hi Guys,

Easiest way out. Remove the existing switch from the wall completely(After cutting power). You will be left with a Live, Nuetral and Earth wire sticking out of the wall. Install the timer here.

Now re install the switch next to it and wire from the timer to it. Use 2.5 cable only.

Point to note, even though your battery keeps the timer going yadda yadda yadda, it will not activate the switch. The battery in these timers usually only keeps the program and clock correct.

Do not mess around with the heat resistant flex that is currently wired to the immersion.