Immersion Switch - Question on Wiring

sona_sasta

Hi,
I'm wiring an immersion switch like this:

I have wired brown to L-IN, black to N-IN
I have connected L-OUT to COM. When I check L-1 and L-2 with a phase tester when the on-off switch is on they are both live no matter how I switch the Bath-Sink switch.
Does this mean the switch is defective? I would expect one to be live at a time depending on whether Bath or Sink is on?
Thanks

mikehammer67

sounds like you're wiring the immersion flex into the supply side of switch

brown and black from the flex connect to L1 and L2 on the switch

Philip82

Wire: Mains brown=Lin
Mains blue=Nin
Imm Flex Brown=L1
Imm Flex Blue=Nout
Imm Flex Black=L2

Use a piece of 2.5mm brown wire (same size as brown in mains supply to switch) and loop between Com+Lout
Earths together in earth terminal.

sona_sasta

Philip82 wrote: »

Wire: Mains brown=Lin
Mains blue=Nin
Imm Flex Brown=L1
Imm Flex Blue=Nout
Imm Flex Black=L2

Use a piece of 2.5mm brown wire (same size as brown in mains supply to switch) and loop between Com+Lout
Earths together in earth terminal.

I'm pretty sure this is how I've wired it, the only difference is that my Mains Neutral is black, I think this happens sometimes? Either way I don't have a blue on the supply mains.

I had a closer look last night and I think I know what is happening. I have a dual element immersion. Where the thermostat is on the combined neutral like this
If L1 is active, I believe the current is entering the immersion, travelling through the element hitting the thermostat which is off, re-entering the 2nd immersion element and making the L2 connection live?


Does that look correct?

Philip82

If you have a black nuetral do have a red live, the old cable colours were red and black. Check with a multimeter if you have 230v on your incoming cable first of all. To me it sounds like you have no nuetral either at the switch or travelling through the switch.

mikehammer67

sona_sasta wrote: »

If L1 is active, I believe the current is entering the immersion, travelling through the element hitting the thermostat which is off, re-entering the 2nd immersion element and making the L2 connection live?

yes
that happens when the stat cuts out

Cerco

mikehammer67 wrote: »

yes
that happens when the stat cuts out

When the stat cuts off the current ceases to flow. If you still have current flowing then you have wrong wiring.

To trouble shoot this problem you need a multimeter. A phase tester is pretty useless other than to indicate the presence of a voltage.

mikehammer67

Cerco wrote: »

When the stat cuts off the current ceases to flow. If you still have current flowing then you have wrong wiring.

To trouble shoot this problem you need a multimeter. A phase tester is pretty useless other than to indicate the presence of a voltage.

no

you get a back feed when the stat cuts out

Cerco

mikehammer67 wrote: »

no

you get a back feed when the stat cuts out

When the circuit is open, no current flows. When the stat opens then there is no circuit, so no current flows. I think you are confusing current and voltage here.

mikehammer67

Cerco wrote: »

When the circuit is open, no current flows. When the stat opens then there is no circuit, so no current flows. I think you are confusing current and voltage here.

current and voltage eh...........:rolleyes:

Bruthal

Cerco wrote: »

When the circuit is open, no current flows. When the stat opens then there is no circuit, so no current flows. I think you are confusing current and voltage here.

Mike is spot on, with stat closed, the element which is not switched on by the bath/sink switch is held at neutral potential. When stat opens, the two elements are connected only to the live via the selector switch, with the now disconnected common neutral terminal connected to nothing.

You are incorrect to say there is no circuit, as the circuit is through sw1 and sw2, through the 18 ohm bath element, through the 23ohm sink element, to the switch and through the phase tester and the user, to earth/neutral.

So it is yourself who is somewhat confused by element-ary stuff possibly.

Bruthal

mikehammer67 wrote: »

current and voltage eh...........:rolleyes:

The answer to everything, it's not the voltage, its the current......

mikehammer67

there's raisons for everything and currants for cakes:pac:

Bruthal

It would be fun trouble shooting with the multi-meter, when nothing is wrong. No raison to be testing it...

Cerco

Bruthal wrote: »

Mike is spot on, with stat closed, the element which is not switched on by the bath/sink switch is held at neutral potential. When stat opens, the two elements are connected only to the live via the selector switch, with the now disconnected common neutral terminal connected to nothing.

You are incorrect to say there is no circuit, as the circuit is through sw1 and sw2, through the 18 ohm bath element, through the 23ohm sink element, to the switch and through the phase tester and the user, to earth/neutral.

So it is yourself who is somewhat confused by element-ary stuff possibly.

I think you should go back to basics and review your reply. Your are wrong!

When the stat is open no current flows. This is precisely why the supply voltage appears on each end of the elements because there is no voltage drop across either of them. Review the sketch. The closing stat makes the circuit through the selected element. When the stat is open the circuit is open. Hence no current. QED

Bruthal

Cerco wrote: »

I think you should go back to basics and review your reply. Your are wrong!

When the stat is open no current flows. This is precisely why the supply voltage appears on each end of the elements because there is no voltage drop across either of them. Review the sketch. The closing stat makes the circuit through the selected element. When the stat is open the circuit is open. Hence no current. QED

Thats interesting, since earlier you said this.....

Cerco wrote: »

To trouble shoot this problem you need a multimeter. A phase tester is pretty useless other than to indicate the presence of a voltage.

... and there was never anything actually wrong. Good look trouble shooting a properly working immersion.

Since there was never any problem with the immersion, and you told a poster who said its normal for an immersion selector to indicate both L1 and L2 as live when the stat opens, that he was mixing up current and voltage, then I dont know how you are claiming anyone is wrong. This is beyond simplicity at the very lowest level in fairness.

gctest50

Cerco wrote: »

I think you should go back to basics and review your reply. Your are wrong!

When the stat is open no current flows. This is precisely why the supply voltage appears on each end of the elements because there is no voltage drop across either of them. Review the sketch. The closing stat makes the circuit through the selected element. When the stat is open the circuit is open. Hence no current. QED

Indeed

Cerco wrote: »

Dropped a brush in the boiler room and disconnected the mains input to the thermostats. When I opened the cover the lead was hanging free. The cable restraint was not holding the cable tightly in place.

I reconnected the input lead to the first pin and the boiler is firng up okay. I just want to be sure I got it right.

Pins 2 is free. 3 & 4 are connected together. Pin 5 is free and Pin 6 is the output power to the boiler.
Anybody familiar with the wiring on these thermostats.
Trying to figure out how to attach a pic.

Cerco wrote: »

Pic attached , I hope

Bruthal

The immersion stat expert confused by 2 boiler stats in series, who`d have thought it.

mikehammer67

double trouble wah

Bruthal

mikehammer67 wrote: »

double trouble wah

I know what he is getting at with the no current flowing with stat open etc. But no one was claiming any current flows with the stat open, but it does when the out of circuit element is touched with a phase tester and it lights, and the stat is open. As you said yourself.

Cerco

Bruthal wrote: »

The immersion stat expert confused by 2 boiler stats in series, who`d have thought it.

Just goes to show how much I learned in such a short time.
It was the OP who wrote about current flow when the stat was open. Mike assured him that was normal.
I think we are all agreed now that no current flows when the stat is open in a correctly wired system. If indeed there was a current flowing then a phase tester would not suffice to troubleshoot.

Bruthal

Cerco wrote: »

Just goes to show how much I learned in such a short time.
It was the OP who wrote about current flow when the stat was open. Mike assured him that was normal.

The fundamental item you missed though, current flows when the phase tester is lighting. But only (through the phase tester) when the stat is open.

That is what mike said. Because he used the word backfeed, you added complexity to a simple item, so simple in reality, that a little intuition would have shown what mike was saying.

I think we are all agreed now that no current flows when the stat is open in a correctly wired system. If indeed there was a current flowing then a phase tester would not suffice to troubleshoot.

Do you honestly think that lads here think there is current flow in a heater when the stat is open? And that you have now shown us the way?

mikehammer67

Cerco

you should post more often if you have an interest in electrical work

no harm in a bit of banter

Bruthal

I dont know, threads seem to close before a bit of banter starts these days:pac:

Cerco

Bruthal wrote: »

The fundamental item you missed though, current flows when the phase tester is lighting. But only (through the phase tester) when the stat is open.

That is what mike said. Because he used the word backfeed, you added complexity to a simple item, so simple in reality, that a little intuition would have shown what mike was saying.



Do you honestly think that lads here think there is current flow in a heater when the stat is open? And that you have now shown us the way?

No, I was not trying to show the lads the way. My reason for posting was to assist the OP in understanding the set up. I felt it was necessary to be precise so the OP could gain some knowledge. I am sorry if you misunderstood this.

Bruthal

Cerco wrote: »

No, I was not trying to show the lads the way. My reason for posting was to assist the OP in understanding the set up. I felt it was necessary to be precise so the OP could gain some knowledge. I am sorry if you misunderstood this.

In electrical, I mis-understand everything.

Anyway, as mike says, keep posting.

Think tank 1

Hi. I'm trying to put a new switch for the immersion heater. I'm not sure if the immersion is actually working. But I would like to get the switch sorted first. I have old wiring. Red L. I have followed an order thread. I have wired it in the following way.
From the mains
RED_Lin
Black_NIn
From the immersion.
Blue - Nout
Brown L1
Black L2
I then looped common to Lout and it tripped the ECB in the fuse box.

Think tank 1

Hi. I'm trying to put a new switch for the immersion heater. I'm not sure if the immersion is actually working. But I would like to get the switch sorted first. I have old wiring. Red L. I have followed an order thread. I have wired it in the following way.
From the mains
RED_Lin
Black_NIn
From the immersion.
Blue - Nout
Brown L1
Black L2
I then looped common to Lout and it tripped the ECB in the fuse box.

brightspark

What is that mark on the red cable??? looks damaged.

Why are you putting on a new switch??

Think tank 1

brightspark wrote: »

What is that mark on the red cable??? looks damaged.

Why are you putting on a new switch??

Hi. The old switch was very old. I just want to have the immersion as back up incase the gas boiler breaks.

brightspark

Was the immersion working before you changed the switch?