Pull switch with neon for switched live

[fiercertonks]

Hello,

I installed a loft extractor fan and the switched live was on a SPST pull switch so the timer worked. The trouble was that we couldn't tell if the fan was on, or off and running on the timer.
I bought a pull switch with a neon indicator, and this is DPDT. I can wire it up so it works as a switch, but the neon indicator does not light up. I want it to light up when the fan is on. I have tried all sorts of combinations, but I suspect it won't ever work as I need the neutral.
Is there a way to make this work on the switched live cable only?

 

[EFLImpudence]

No.

 

[Lectrician]

You need a three core and earth cable taken to in.

 

[JohnW2]

I bought a pull switch with a neon indicator, and this is DPDT.

Are you sure? As I often observe, sometimes to my annoyance, DPDT electrical accessories do not seem to exist. Are you sure it's not just DP on/off (DPST)?

I can wire it up so it works as a switch, but the neon indicator does not light up. I want it to light up when the fan is on. I have tried all sorts of combinations, but I suspect it won't ever work as I need the neutral. Is there a way to make this work on the switched live cable only?

As you've been told, the short/simple answer is 'no'. However, it's possible that you may be able to get it to work 'back-to-front' - i.e. such that the neon is on when the switch is off, and vice versa - would that be any use to you, or would it be too confusing?

Kind Regards, John

 

[AndyPRK]

Considering the fan is a timer model and the switched input would be high impedance I doubt a neon would work. I nearly suggested it.

 

[JohnW2]

Considering the fan is a timer model and the switched input would be high impedance I doubt a neon would work. I nearly suggested it.

Yes, I thought of that and that's why I only suggested that it was 'possible' that it would work. I actually suspect that it might (work) - tiny amounts of current are enough to light neons (neon screwdrivers usually work, without our usually feeling any current) - the series resistor on the trigger input of a timer fan is usually between 150kΩ and 300kΩ, appreciably less than that in a neon screwdriver (and probably illuminated switch).

Kind Regards, John

 

[fiercertonks]

Hi and thanks for the replies. Im not sure I understood them all as you guys seem more technical, and Im a DIYer, but I managed to work it out in the end. Excuse the lack of technical terminology.

I wired the switched live to one of the poled switches, and I wired the permanent neutral downstream of the other poled switch. It all works as I wanted, i.e. neon on when the fan is on, and off when off and/ or running on timer.

 

[JohnW2]

Hi and thanks for the replies. Im not sure I understood them all as you guys seem more technical, and Im a DIYer, but I managed to work it out in the end. Excuse the lack of technical terminology.

You're welcome. The more techie stuff was really about the situation if you didn't have a neutral - but you seem to have found one!

I wired the switched live to one of the poled switches, and I wired the permanent neutral downstream of the other poled switch. It all works as I wanted, i.e. neon on when the fan is on, and off when off and/ or running on timer.

As above, I presume that you found a neutral somewhere - where did you 'find' it, and how did you get it to the switch?

Kind Regards, John

 

[sparkwright]

Remind me what DPDT or SPST means...

Obviously double pole something, and single pole something...

 

[JohnW2]

Remind me what DPDT or SPST means..
Obviously double pole something, and single pole something...

DPDT = Double Pole, Double Throw (i.e. 2-pole changeover, common in toggle switches, never seen {AFAIAA} in electrical accessories)
SPST = Single Pole, Single Throw (standard SP on/off, or '1-way')
also
DPST = Double Pole, Single Throw (standard DP on/off)
SPDT = Single Pole Double-Throw (as in standard '2-way' light switches)

Kind Regards, John

 

[333rocky333]

Remind me what DPDT or SPST means...

Obviously double pole something, and single pole something...

Isnt that like a Double pole with centre off and you can switch up or down,

 

[JohnW2]

Remind me what DPDT or SPST means...

Isnt that like a Double pole with centre off and you can switch up or down,

Not per se .... DPDT is just DPDT, as described in my previous post - just two ('changeover') positions. "DPDT-centre off" has the additional centre position, in which nothing is connected to anything. Only seen in toggle switches etc, never (AFAIAA) in electrical accessories.

Kind Regards, John

 

[ban-all-sheds]

Only seen in toggle switches etc, never (AFAIAA) in electrical accessories.

Except momentary ones.

 

[fiercertonks]

Hi,

I had a neutral all along, as I am using 3 core for the fan. I only had the switched live in the switch beforehand and it took me a while to work out I would need to attach the neutral for the neon to work. I had to draw the circuit on paper a few times.

The switch itself was from amazon:

http://www.amazon.co.uk/Double-Pole...ble+Pole+Pull+Switch+With+Neon#productDetails

 

[ban-all-sheds]

I had a neutral all along, as I am using 3 core for the fan.

That leaves you 1 short.

1. Permanent live
2. Switched live
3. Neutral
4. Earth

Did you mean 3-core and earth cable?