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Extractor fan relay for two independent light switches

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metanet

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Thinking a 240V AC relay activated by two independent light switches could be used to switch power to a shared inline extractor fan. The fan serves two bathrooms, just needs to be activated from two different switched live lighting circuits.
I'm aware double pole light switches could be used in this scenario but the light switches didn't pass wife test.

Anyone know of a dual input relay I could use for this purpose?

Thanks
Meta
 
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metanet said:
Thinking a 240V AC relay activated by two independent light switches could be used to switch power to a shared inline extractor fan. The fan serves two bathrooms, just needs to be activated from two different switched live lighting circuits.
I'm aware double pole light switches could be used in this scenario but the light switches didn't pass wife test.

Anyone know of a dual input relay I could use for this purpose?

Thanks
Meta
Click to expand...
Just use a double pole single gang switch, it's much easier.

Or if you're adamant on not using switches, then you could use a two input solid state relay.
 
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DefyG said:
Still cant see point of using 2 relays though
Click to expand...
Well lets say I needed to do the above job, I've just been on google, typed in dual input relay and then clicked products, this is what came up.


I'm none the wiser which relay I should buy out of that lot, so I can either take a guess and end up with the wrong thing costing me a days work or I could buy 2 relays and do it that way very easily. Is that a good enough point.
 
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oscar21 said:
Well lets say I needed to do the above job, I've just been on google, typed in dual input relay and then clicked products, this is what came up.


I'm none the wiser which relay I should buy out of that lot, so I can either take a guess and end up with the wrong thing costing me a days work or I could buy 2 relays and do it that way very easily. Is that a good enough point.
Click to expand...


I can't see how using a pair of relays/contactors are going to be in any way easy.

They would need to be mounted properly in an enclosure that's suitable.

Contactors in the consumer unit is going to be no easy task and also costly.

The easiest, cheapest, quickest, and Compliant way is to use a pair of 1 gang dp switches as already said.
 
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oscar21 said:
Well lets say I needed to do the above job, I've just been on google, typed in dual input relay and then clicked products, this is what came up.


I'm none the wiser which relay I should buy out of that lot, so I can either take a guess and end up with the wrong thing costing me a days work or I could buy 2 relays and do it that way very easily. Is that a good enough point.
Click to expand...

Why don't you try "two input solid state relay", like i posted #7


[ElectriciansForums.net] Extractor fan relay for two independent light switches
 
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Sorry, no diagram, but here goes.
Relay coil to one light S/L, relay pulls in when that light is on.
Contact (needs to be C/O) common to fan S/L input.
Connect contact N/O to same S/L as coil.
Connect N/C contact to S/L on other light.

Switching one light on pulls in the relay, changes over the contacts, and applies live to fan control. Fan runs.
With that light off, tge fan is controlled by the other light as if the relay wasn't there.

The above assumes bith lights on same circuit. If on different circuits, relay coil S/L & N come from one circuit. The N/O contact must connect to the permanent L the fan is connected to - needs an extra cable core.
 
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Oh yes, the relay will hum when on. It's possible to add a couple of diodes so the coil operates on DC, and it's inductance will smooth out the half wave and eliminate the hum.

Also, depending on the fan, it may be possible to just use two diodes so when either light is on, the fan control input is fed with half wave DC. This will be sufficient to trigger the timer on many fans.
 
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Simon47 said:
Sorry, no diagram, but here goes.
Relay coil to one light S/L, relay pulls in when that light is on.
Contact (needs to be C/O) common to fan S/L input.
Connect contact N/O to same S/L as coil.
Connect N/C contact to S/L on other light.

Switching one light on pulls in the relay, changes over the contacts, and applies live to fan control. Fan runs.
With that light off, tge fan is controlled by the other light as if the relay wasn't there.

The above assumes bith lights on same circuit. If on different circuits, relay coil S/L & N come from one circuit. The N/O contact must connect to the permanent L the fan is connected to - needs an extra cable core.
Click to expand...
[ElectriciansForums.net] Extractor fan relay for two independent light switches
 
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suffolkspark said:
Id just get another inline fan probably as cheap as relays and enclosures
Click to expand...
You can fit a relay in a backbox - and you'll most likely have one already for an isolation/maintenance switch. And it'll cost (if you pick sensibly) less than some of the switches people have been suggesting, and definitely less than an extra fan.
 
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Like Simon47, Post #14 I was assuming all to be on same RCD protected circuit and maybe just a L & S/L at the switch! in an existing installation with loft access. Maybe it is being wired from scratch so is open to other options, but just re-read OP's post ........
metanet said:
from two different switched live lighting circuits.
Click to expand...
TWO different circuits requires a different solution!
 
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