Front of House Lights Setup

[JohnW2]

I would have the PIR bypass the time control and photocell completely.

Actually, on reflection, that's what I do have. The (multiple) PIRs and/or the timeswitch/photocell combination both switch power (when activated) to a common feed to the (several) lights.

Grasslin immersion timers have volt free contacts with the link removed, as do many others. Bog standard DIY type. If you look, you will find.

I've often looked, but have very rarely found (admittedly, I'm not familiar with Grasslin ones). As the pic below shows, it's certainly not possible with the ubiquitous 'bog standard' Smiths/ Timeguard/ variants/ copies - the L feed to the motor comes from close to the contacts, deep inside the device. Indeed, even if one was prepared to undertaken surgery which went well beyond what one could expect of an average DIYer, there would be some bodging necessary, since they usually don't even have enough terminals for 'volt-free' use. There's usually just five - an L&N in, an L&N (L switched) out (the two N's being 'hard linked') and an earth. If one wanted to convert it (or most others I've seen) for 'volt-free' use, one would either have to try (assuming both motor supply and load were on same circuit) to unlink the two N's, and then use one of them for the required additional terminal, or else sacrifice the earth terminal, and use something else to terminate the CPCs in. ... certainly not just a question of 'removing a link

Trivial but IMO not professional. There us little excuse to not get a volt free type, and let the photocell stay powered (how it is intended).

Perhaps I'm naive, but it's always been my assumption that not leaving the photocell powered permanently would increase its life (they don't last for ever at the best of times) - it may well have been that believe that caused me to wire it the way I did (many years ago). Do I take it that my belief is wrong?

The time clock should be set with a view of OFF period, not on. You should be setting the times you want it OFF.

Of course - that's what it's there for. What other purpose would the timeswitch serve? The photocell switches the lights on, and the timeswitch switches them off.

Kind Regards, John

 

[JohnW2]

I have just realised that you are talking about John's situation and not the OP's.

I was under the impression that my 'situtaion' (at least, required functionality) was identical to the OP's. What difference do you perceive?

Do photocells have a set-up period?

Yes, most do. That's why, as I said. my outside lights all come on for about 30 seconds around 2.30pm every day.

Kind Regards, John

 

[EFLImpudence]

Yeah but, no but.

It is now.

You wrote:
I have timeswitch (NOT volt-free) -> photocell -> (multiple) PIRs -> lights.

meaning the PIR set-up period occurs every day.

 

[JohnW2]

Yeah but, no but. It is now.
You wrote: I have timeswitch (NOT volt-free) -> photocell -> (multiple) PIRs -> lights.
meaning the PIR set-up period occurs every day.

Well, yes, but even if what I had written were true, it wouldn't have really mattered, since the 'PIR set-up period' and 'photocell set-up period' would happen concurrently. However, given my subsequent correction, what I actually have is:

timeswitch (NOT volt-free) -> photocell -> lights
(multiple) PIRs (permanently powered) ------^
(and for good measure!) manual switch------^

... so I get a brief 'photocell set-up period' each afternoon, but that's all.

Kind Regards, John

 

[EFLImpudence]

True (now) but the PIR set-up may be twenty minutes.

Not the end of the world but avoidable.

 

[JohnW2]

True (now) but the PIR set-up may be twenty minutes.

Yes, it could be - but that would happen with the arrangement you proposed

Not the end of the world but avoidable.

AFAICS, the only way of totally avoiding 'set-up periods' would be to adopt Lectrician's (ideal) approach, using a timer with 'volt-free' contacts (and enough terminals!) - but, as I have indicated, it might not be as easy to find 'the needful' to do that as he seems to be suggesting. Although he has indicated that at least one exists, I can't say that I've personally seen a 'consumer/DIY timeswitch' which has a removable link. Particularly if used for the intended purpose (immersion) no ordinary consumer would have reason to remove such a link, would they?

Kind Regards, John

 

[EFLImpudence]

True (now) but the PIR set-up may be twenty minutes.

Yes, it could be - but that would happen with the arrangement you proposed

No, it wouldn't.

Not the end of the world but avoidable.

AFAICS, the only way of totally avoiding 'set-up periods' would be to adopt Lectrician's (ideal) approach, using a timer with 'volt-free' contacts (and enough terminals!) - but, as I have indicated, it might not be as easy to find 'the needful' to do that as he seems to be suggesting. Although he has indicated that at least one exists, I can't say that I've personally seen a 'consumer/DIY timeswitch' which has a removable link. Particularly if used for the intended purpose (immersion) no ordinary consumer would have reason to remove such a link, would they?

Not for an immersion in the normal situation.

The one mentioned:
http://www.alertelectrical.com/uploads/prod/865grasti24.pdf

It does have quite a low rating for flourescent lamps.

 

[JohnW2]

Yes, it could be - but that would happen with the arrangement you proposed

No, it wouldn't.

Right, the lights would not come on for 20 minutes (or whatever), but they would come on for whatever was the 'set-up period' of the photocell. I thought you were implying that your method would avoid all 'set-up periods'.

The one mentioned:
http://www.alertelectrical.com/uploads/prod/865grasti24.pdf
It does have quite a low rating for flourescent lamps.

Indeed - seemingly ridiculously low .... and what sort of load do they think that incandescent lamps represent? - why 16A 'resistive load' but only 1350W (<6A) incandescent lamp load?? Is there some explanation for all this, or do they not know what they are talking about?

In order to have enough terminals for both 'volt-free' and NO/NC contacts, they have eliminated both the usual neutral terminals and the earth terminal. They mention an 'earth parking terminal', somewhere, but what is one meant to do with the neutrals? Is this perhaps intended for 'wire-through' applications?

Other than the application we're talking about, probably the only 'common' situation I can think of in which one might want 'volt-free' contacts on a device like this is if (for some reason) one wants to restrict the on-time of an immersion fed from an E7 etc. supply - but I'm not really sure why anyone would/should want to do that. Nor do I think that many consumers/DIYers would want the NC contact. Is this device perhaps aimed at some other market?

Kind Regards, John

 

[EFLImpudence]

Yes, it could be - but that would happen with the arrangement you proposed

No, it wouldn't.

Right, the lights would not come on for 20 minutes (or whatever), but they would come on for whatever was the 'set-up period' of the photocell. I thought you were implying that your method would avoid all 'set-up periods'.

Ah. Crossed purposes, again. Sorry.

 

[JohnW2]

The one mentioned: .... It does have quite a low rating for flourescent lamps.

Indeed - seemingly ridiculously low .... and what sort of load do they think that incandescent lamps represent? - why 16A 'resistive load' but only 1350W (<6A) incandescent lamp load?? Is there some explanation for all this, or do they not know what they are talking about?

... and I've also just noticed ... what is this all about?? ...

Minimum switching current 100mA (20v) AC/DC

(it's presumably an electromechanical device, isn't it?).

Kind Regards, John

 

[EFLImpudence]

and I've also just noticed ... what is this all about?? ...

Minimum switching current 100mA (20v) AC/DC

(it's presumably an electromechanical device, isn't it?).

I believe it relates to the volt free contacts.

http://control.com/thread/1026229568

 

[JohnW2]

and I've also just noticed ... what is this all about?? ...

Minimum switching current 100mA (20v) AC/DC

(it's presumably an electromechanical device, isn't it?).

I believe it relates to the volt free contacts. http://control.com/thread/1026229568

Well, the 'volt-free contacts' are all it's got to do any switching with, so it must relate to them! ... but 'volt-free' contacts are simply 'contacts' which are not connected to anything internally - so in no way 'special'. I suppose that, to me, 'minimium switching current' implies 'minimum breaking current' - a concept which makes no real sense. As per your link, problems, if they arise, with low current, low voltage switching (with switches or relays) relate to the quality of 'making', rather than than breaking current - and its pretty unusual to see a 'minimum current' specified for either switches or relay contacts.

Whatever, I think this somewhat underlines my question about what market (and/or applications) this device is actually intended for. It is described as an 'Immersion heater timeswitch' yet (apart from the E7 situation I mentioned before) I think I would struggle to think of reasons why anyone would normally need 'volt-free' contacts, changeover contacts or to be switching 20V for that application!

Kind Regards, John

 

[EFLImpudence]

I suppose you could fit one to switch whatever you wanted; for some of which it may not be suitable.

It is, after all, a minimum - which may only exclude very few things about which the manufacturer does not wish to receive complaints that it does not work.

 

[JohnW2]

I suppose you could fit one to switch whatever you wanted; for some of which it may not be suitable.

Indeed so. The likes of you and I might well use it for all sorts of purposes, and the 'volts-free' contacts, and changeover contacts, might well be valuable to us for our intended purpose. Maybe it's just me, but I would not really have expected such a potentially useful and versatile device to be sold as an 'Immersion timeswitch'!

It is, after all, a minimum - which may only exclude very few things about which the manufacturer does not wish to receive complaints that it does not work.

That's possible, but the information provided is very limited. They tell us only what the minimum current is at 20V AC/DC - so we don't even know what (if anything other than 'zero') is the minimum current at 24V - if the minimum is 100mA at 20V, it seems unlikley that it would be zero at 24V! Perhaps more to the point, given that 99%+ of users are probably going to use it to switch 230V AC (with the link in place), what (if anything) is the 'minimum current' at that voltage?

Kind Regards, John

 

[EFLImpudence]

I don't really know what "100mA(20V)" means.

Surely Minimum Switching Current is either that (at all voltages) or variable.

Other products are similarly specified and some don't mention MSC.