Hecklar Registered User
#1

Hey guys.

I'm hoping some of you might be able to give me some info on an old immersion heater and how its wired. I'm going to attempt to replace an immersion heater switch that is acting up, later this evening. It's a simple ON/OFF - SINK/BATH type of switch and looks to be from the 60's-70's.

I took a quick shot of the top of the immersion heater and I was hoping to get my head around how its wired before I make an attempt at the switch.
(Invalid img)
https://imgur.com/a/PZ35eDw

All the wires are black and there are 4 terminals marked as follows,
RED,
BLUE,
WHITE,
BLACK.

The black is marked on the housing as "long element (Bath)" and goes to the L1 terminal in the bath/sink switch.
The white goes to the L2 terminal in the bath/sink swtich.

The terminals marked RED and BLUE both go to the switched side of the neutral in the switch.

I guess what I'm trying to get to the bottom of, is how this element works. It appears to me to be fed a live to the black or white (depending on sink/bath position) and the switching is on the neutral side (It appears to have some burning/arcing here on the old switch). Overall, the wiring looks very janky and hasn't been touched for years, by the looks of it.

I've tried searching online for diagrams etc and I found some info on old/wiring colours, but I haven't been able to find anything similar to this.
The heater itself is branded "Santon Otter". There are some other details on it but I forgot to take a pic. I can do so later if needed.

*Note: I took the cover off to have a peek inside in the image above. It's not actually exposed like that normally.

Any help appriciated guys.

John.G Registered User
#2

Hecklar said:
Hey guys.

I'm hoping some of you might be able to give me some info on an old immersion heater and how its wired. I'm going to attempt to replace an immersion heater switch that is acting up, later this evening. It's a simple ON/OFF - SINK/BATH type of switch and looks to be from the 60's-70's.

I took a quick shot of the top of the immersion heater and I was hoping to get my head around how its wired before I make an attempt at the switch.
(Invalid img)
https://imgur.com/a/PZ35eDw

All the wires are black and there are 4 terminals marked as follows,
RED,
BLUE,
WHITE,
BLACK.

The black is marked on the housing as "long element (Bath)" and goes to the L1 terminal in the bath/sink switch.
The white goes to the L2 terminal in the bath/sink swtich.

The terminals marked RED and BLUE both go to the switched side of the neutral in the switch.

I guess what I'm trying to get to the bottom of, is how this element works. It appears to me to be fed a live to the black or white (depending on sink/bath position) and the switching is on the neutral side (It appears to have some burning/arcing here on the old switch). Overall, the wiring looks very janky and hasn't been touched for years, by the looks of it.

I've tried searching online for diagrams etc and I found some info on old/wiring colours, but I haven't been able to find anything similar to this.
The heater itself is branded "Santon Otter". There are some other details on it but I forgot to take a pic. I can do so later if needed.

*Note: I took the cover off to have a peek inside in the image above. It's not actually exposed like that normally.

Any help appriciated guys.


If you do a search for "Immersion Wiring" in the Boards.ie search box you will get lots of useful info there.
As a matter of interest I have a Santon (Otter Duastat) dual immersion which I installed in November 1972 and still in perfect condition but its only a 3 wire supply as the switching was/is done on the immersion top (see photo), if its any help to you the bath/sink element resistances are 16.7/23.1 ohms (3.2/2.3 KW @ 230V).
I would think that yours might be more likely from the 80's but the wiring colours were explained a number of times in various posts.

If you are handy and careful you can check out the wiring from the immersion back to the switch with a multimeter as its more than likely that it was wired correctly first day.

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Hecklar Registered User
#3

John.G said:
If you do a search for "Immersion Wiring" in the Boards.ie search box you will get lots of useful info there.
As a matter of interest I have a Santon (Otter Duastat) dual immersion which I installed in November 1972 and still in perfect condition but its only a 3 wire supply as the switching was/is done on the immersion top (see photo), if its any help to you the bath/sink element resistances are 16.7/23.1 ohms (3.2/2.3 KW @ 230V).
I would think that yours might be more likely from the 80's but the wiring colours were explained a number of times in various posts.


Hey. Thanks for the info.
I did do a search before I posted and there's a bit of talk of various colour schemes for the wiring, but nobody seemed to mention the colours mine is using and of course, all the wiring in mine is a single colour so I just wanted to put it out there and see if anyone with more experience than me could shed some light on it.

Cheers.

sky6 Registered User
#4

You might be better posting it over in the Electrical section where it will be viewed by a lot of Electricians and Engineers.

Sleeper12 Registered User
#5

sky6
You might be better posting it over in the Electrical section where it will be viewed by a lot of Electricians and Engineers.


I agree.
I would imagine that they would recommend replacing the cable from the immersion to the switch as well as replacing the switch.

John.G Registered User
#6

Hecklar said:
Hey. Thanks for the info.
I did do a search before I posted and there's a bit of talk of various colour schemes for the wiring, but nobody seemed to mention the colours mine is using and of course, all the wiring in mine is a single colour so I just wanted to put it out there and see if anyone with more experience than me could shed some light on it.

Cheers.


There is some very good info it this thread which you may not have seen before.

https://www.boards.ie/vbulletin/showthread.php?t=2057413946

1 person has thanked this post
Hecklar Registered User
#7

sky6 said:
You might be better posting it over in the Electrical section where it will be viewed by a lot of Electricians and Engineers.


Yeah I maybe should have posted over there. It was 50/50 really.

Hecklar Registered User
#8

John.G said:
There is some very good info it this thread which you may not have seen before.

https://www.boards.ie/vbulletin/showthread.php?t=2057413946


I did indeed find this link. There's plenty of useful info but the colour schemes don't fit with mine unfortunately.

aido79 Moderator
#9

Hecklar said:
Hey guys.

I'm hoping some of you might be able to give me some info on an old immersion heater and how its wired. I'm going to attempt to replace an immersion heater switch that is acting up, later this evening. It's a simple ON/OFF - SINK/BATH type of switch and looks to be from the 60's-70's.

I took a quick shot of the top of the immersion heater and I was hoping to get my head around how its wired before I make an attempt at the switch.
(Invalid img)
https://imgur.com/a/PZ35eDw

All the wires are black and there are 4 terminals marked as follows,
RED,
BLUE,
WHITE,
BLACK.

The black is marked on the housing as "long element (Bath)" and goes to the L1 terminal in the bath/sink switch.
The white goes to the L2 terminal in the bath/sink swtich.

The terminals marked RED and BLUE both go to the switched side of the neutral in the switch.

I guess what I'm trying to get to the bottom of, is how this element works. It appears to me to be fed a live to the black or white (depending on sink/bath position) and the switching is on the neutral side (It appears to have some burning/arcing here on the old switch). Overall, the wiring looks very janky and hasn't been touched for years, by the looks of it.

I've tried searching online for diagrams etc and I found some info on old/wiring colours, but I haven't been able to find anything similar to this.
The heater itself is branded "Santon Otter". There are some other details on it but I forgot to take a pic. I can do so later if needed.

*Note: I took the cover off to have a peek inside in the image above. It's not actually exposed like that normally.

Any help appriciated guys.


No offence but if you're talking about the switching being on the neutral side and putting up pictures like that then it's time to ring an electrician or a little bit of arcing will be the least of your worries.
Get the job done properly by replacing the cable from the switch to the elements while you're at it.

Hecklar Registered User
#10

aido79 said:
No offence but if you're talking about the switching being on the neutral side and putting up pictures like that then it's time to ring an electrician or a little bit of arcing will be the least of your worries.
Get the job done properly by replacing the cable from the switch to the elements while you're at it.


Ultimately, that's the plan. I'll be replacing the entire cylinder soon but I needed to get it up and running for the time being.

I should probably have mentioned though, I'm not coming at it completely blind. I have an engineering background. I'm just not that familiar with old skool domestic stuff so I figured I'd ask for info.

It's all done now, though I found some wear further down the cable so I'll be pulling a new run to the consumer unit when replacing the cylinder.

Thanks for the info, everyone.

1 person has thanked this post
Wearb Moderator
#11

Hecklar said:
Ultimately, that's the plan. I'll be replacing the entire cylinder soon but I needed to get it up and running for the time being.

I should probably have mentioned though, I'm not coming at it completely blind. I have an engineering background. I'm just not that familiar with old skool domestic stuff so I figured I'd ask for info.

It's all done now, though I found some wear further down the cable so I'll be pulling a new run to the consumer unit when replacing the cylinder.

Thanks for the info, everyone.

Just a heads up: The new run will need to be installed by an electrician to comply with statutory regs.

1 person has thanked this post
aido79 Moderator
#12

Hecklar said:
Ultimately, that's the plan. I'll be replacing the entire cylinder soon but I needed to get it up and running for the time being.

I should probably have mentioned though, I'm not coming at it completely blind. I have an engineering background. I'm just not that familiar with old skool domestic stuff so I figured I'd ask for info.

It's all done now, though I found some wear further down the cable so I'll be pulling a new run to the consumer unit when replacing the cylinder.

Thanks for the info, everyone.


I just hope you're not an electrical engineer if you're having trouble understanding how an immersion works.

As advised definitely get an electrician to run the new cable as it would be illegal for you to do it yourself.

Hecklar Registered User
#13

aido79 said:
I just hope you're not an electrical engineer if you're having trouble understanding how an immersion works.

As advised definitely get an electrician to run the new cable as it would be illegal for you to do it yourself.


I understand perfectly well how an immersion works. I asked for clarification on this specific one, as documentation isn't available.

aido79 Moderator
#14

Hecklar said:
I understand perfectly well how an immersion works. I asked for clarification on this specific one, as documentation isn't available.


I have my doubts if you are talking about switching neutrals. An immersion works by switching the live at the on/off switch, the output of this switch is fed to a selector switch for bath or sink. The output of the selector switch goes to either the bath or sink element with the common neutral being fed to the other end of each element.
If you understand how it works and know how to use a multimeter then colours will not be a problem when diagnosing a fault.

John.G Registered User
#15

aido79 said:
I have my doubts if you are talking about switching neutrals. An immersion works by switching the live at the on/off switch, the output of this switch is fed to a selector switch for bath or sink. The output of the selector switch goes to either the bath or sink element with the common neutral being fed to the other end of each element.
If you understand how it works and know how to use a multimeter then colours will not be a problem when diagnosing a fault.


One picture is worth a thousand words. (Picture originally courtesy of Bruthal)

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