Dimmed pir and switched line to single bathroom light

[LaurenceM]

I design bathrooms and I'm wondering if it's possible to use the same ceiling lights supplied by both a manual switch and a flush ceiling pir going through a concealed dimmer as a night light.

Looking at most PIRs and from what I understand, if the bathroom rocker switch L1 supplies the lights normally and L2 from the switch feeds permanent live to the PIR, the SL output of which goes through a dimmer, the night-level lighting will come on whenever the lights are turned off, even when no motion is detected. I want to avoid this.

Are there any PIRs that don't activate when initially powered-up? I've also looked at switching using volt-free contact ones but I don't think this solves anything either.

Can anyone recommend a suitable ceiling PIR or a configuration that will work as needed? Thanks

 

[timhoward]

What you want can be done, but it could easily create some confusing wiring and care would be needed to not cause danger by having multiple sources of supply to the same lamps. I don't like the "hidden dimmer" aspect of it very much, as one day that will fail and be need to be found. I'd leave the dimmer high up on other side of door, or somewhere accessible.

A quinetic battery powered PIR and quinetic wireless receiver should overcome the problem of the PIR self tested upon receiving power. You essentially have a wireless PIR controlled relay then.

The simplest solution would probably be a dual quinetics receiver, with the lights connected to channel one, and a dimmer connected from channel 2 to channel 1.
Then the main bathroom light switch paired to channel 1, and the PIR paired to channel 2.
While that should work fine, adding a diode to avoid back-feeding the dimmer / receiver would be belt and braces.

 

[LaurenceM]

What you want can be done, but it could easily create some confusing wiring and care would be needed to not cause danger by having multiple sources of supply to the same lamps. I don't like the "hidden dimmer" aspect of it very much, as one day that will fail and be need to be found. I'd leave the dimmer high up on other side of door, or somewhere accessible.

A quinetic battery powered PIR and quinetic wireless receiver should overcome the problem of the PIR self tested upon receiving power. You essentially have a wireless PIR controlled relay then.

The simplest solution would probably be a dual quinetics receiver, with the lights connected to channel one, and a dimmer connected from channel 2 to channel 1.
Then the main bathroom light switch paired to channel 1, and the PIR paired to channel 2.
While that should work fine, adding a diode to avoid back-feeding the dimmer / receiver would be belt and braces.

Many thanks Tim

From what you say, am I to take that that all wired PIRs will self-test ie: this cycle doesn't vary by manufacturer or product variant?

 

[timhoward]

Many thanks Tim

From what you say, am I to take that that all wired PIRs will self-test ie: this cycle doesn't vary by manufacturer or product variant?

I’m not an expert and can’t answer that other than to say most I’ve encountered seem to. You can get PIR modules to fit in an adaptable box. I have a feeling these don’t do that.
If you have a 12v supply you could use an ordinary intruder alarm PIR and an external relay.
But I’d have thought you probably want to keep it as off-the-shelf as possible.