Photocell for Outdoor Lights

[imroberts]

I'm looking to fit some outdoor lights and I'm contemplating between operating them with a timer or fitting a photocell.

I think the photocell is my preferred option and I'm looking at one of the below:

https://www.screwfix.com/p/ced-standalone-photocell/980cg
https://www.wickes.co.uk/Masterplug-Weatherproof-Dusk-to-Dawn-Timer-Switch---Grey/p/117864

Does anyone have any experience of either of these products or indeed any others?

How far away from my lights do I want to mount the photocell to ensure it operates reliably and isn't triggered by the lights?

 

[flameport]

Photocell of that style - the top can easily be replaced when it fails without changing the wiring.

Distance from the lights doesn't matter - just that the lights won't shine onto the photocell.
Best wired with 4 core flex, rather than solid core cable.

 

[MilkDawg]

IIRC, those photocells have no earth, so 3 core flex using a 20mm gland. As Flameport said, you can swap out the sensor easily without touching wiring but they last years normally.

 

[EFLImpudence]

IIRC, those photocells have no earth, so 3 core flex using a 20mm gland. As Flameport said, you can swap out the sensor easily without touching wiring but they last years normally.

I don't really understand what you are getting at.

 

[MilkDawg]

I don't really understand what you are getting at.

Which part?

 

[EFLImpudence]

Firstly, we don't know if the photocell will be in-line with the supply or connected as a branch from the first light.

IIRC, those photocells have no earth, so 3 core flex using a 20mm gland.

So, might need four-core. A CPC(earth wire) should be run even if not required.
Though if ignoring that, two-core might do.

 

[Adam_151]

MilkDawg, You arn't one of those folk who tape the earth up brown and use it as the switchwire on cells and PIRs are you

Yes, yes, technically not forbidden but rougher than a bear's behind and anyone who does it on anything I'm responsible for will be going back to change it!

 

[FrodoOne]

I'm looking to fit some outdoor lights and I'm contemplating between operating them with a timer or fitting a photocell.

I think the photocell is my preferred option and I'm looking at one of the below:

https://www.screwfix.com/p/ced-standalone-photocell/980cg
https://www.wickes.co.uk/Masterplug-Weatherproof-Dusk-to-Dawn-Timer-Switch---Grey/p/117864

It should be noted that the two products mentioned are quite different, as is reflected in the price.

The first is a simple photocell, which turns ON when the external light drops below a certain point and OFF when the light increases above that point.

The second product can do the same thing BUT it can also be adjusted/programmed to have a selectable ON time of 2, 4, 6, 8 hours. So, with this product you can have it turn on at "dusk" but turn off (say) 6 hours later, when it is likely that no one will be about.

(There are even more sophisticated night sensing devices which "learn" when the night begins and ends as the seasons change and adjust the OFF times accordingly, so that they can be set to shut-off at [roughly] the same time throughout the year - say Midnight, 1:00 am, 2:00 am etc.)

 

[imroberts]

Hmm, I must admit I hadn't considered the combination of a dusk sensor and a timer but that makes a lot more sense.

I don't really need the lights on right through the night, I just want them to come on at dusk and stay on until the latest I tend to come home, so say 6 hours would be sufficient through winter. That seems a lot better option to me

How do the more sophisticated models you mention work? Are you saying I can set an "off" time of, let's say midnight, so through the winter it might come on at 4pm and stay on till midnight, but in the peak of summer it might only run from 10pm to midnight? Do you have an example of such a product?

 

[flameport]

Hmm, I must admit I hadn't considered the combination of a dusk sensor and a timer but that makes a lot more sense.

Before getting involved with complex timers and other arrangements, consider that the cost of running LED lights for a few extra hours is so low as to be practically zero.

 

[FrodoOne]

Hmm, I must admit I hadn't considered the combination of a dusk sensor and a timer but that makes a lot more sense.

I don't really need the lights on right through the night, I just want them to come on at dusk and stay on until the latest I tend to come home, so say 6 hours would be sufficient through winter. That seems a lot better option to me

How do the more sophisticated models you mention work? Are you saying I can set an "off" time of, let's say midnight, so through the winter it might come on at 4pm and stay on till midnight, but in the peak of summer it might only run from 10pm to midnight? Do you have an example of such a product?

I am sorry that I did not get back to you earlier but I was otherwise engaged

The device that generally is used here is a CABAC HSC110SS, the manual for which can be found at https://www.cabac.com.au/shop/media/Pdf/Product/manuals/0010/hsc110ss.pdf
See "4.3 REAL TIME MODE (SWITCH 7 ON & SWITCH 8 OFF)" in these instructions.
(Those who view the Wiring diagram should note that Australian terminology refers to the "Line" connection as the "Active" connection.)
(You will find this product offered on ebay.co.uk at various prices starting at £29.52, plus postage.)


A somewhat similar European (German) product is the "Steinel" NightMatic 3000 Vario
https://www.steinel.de/en/domestic-...-controller/nightmatic-3000-vario-550516.html
which is also available on ebay.co.uk, at similar prices.
The operating instructions for this may be found at https://www.steinel.de/out/media/operationmanual/35262_110070543_BDAL NIGHTMATIC 3000 26 SPR.pdf

Note that the CABAC device uses DIP switches to set the time while the other device uses a potentiometer, which may not allow its adjustment to be quite as accurate (?)

These devices do calculate "midnight plus or minus so many hours or minutes" but do not allow for Summer time.
If you are close to the meridian which designates the "time zone" in which you are located (such as in or near London) the "midnight" determined by these devices will be fairly accurate - throughout the year, ignoring Summer Time.
However, if you live in a place such as Melbourne, where the "local time" is actually 22 minutes behind the "time zone" time, if the device is set to "midnight" it won't turn off until the clock indicates about 12:22 am.

 

[imroberts]

Before getting involved with complex timers and other arrangements, consider that the cost of running LED lights for a few extra hours is so low as to be practically zero.

I must admit that's a very valid point. I'm intending to run 2 x 3W LED lamps which will cost less than £4 a year to run for 12 hours a day - given I can pick up the bog standard photocell for < £10 the extra £20 for the more elaborate option is going to take 5 years to recover the cost... maybe I'll just go for the standard one after all

 

[JohnW2]

I must admit that's a very valid point. I'm intending to run 2 x 3W LED lamps which will cost less than £4 a year to run for 12 hours a day - given I can pick up the bog standard photocell for < £10 the extra £20 for the more elaborate option is going to take 5 years to recover the cost... maybe I'll just go for the standard one after all

Indeed, but the calculation is not quite as simple as that - for example, even with LEDs, one has to factor in that an additional few hours of operation every day (well, on many days) would lead to the need to replace the lamps more frequently.

... and, of course, some would argue that it's not only about the direct financial costs for the owner of the lamps ... if millions of households 'unnecessarily' used 6W for longer each day then they actually needed, that could add/multiply up to a total with more widespread consequences - but most of us don't worry too much about such things!

Kind Regards, John

 

[imroberts]

I have another question around positioning of the photocell.

The front of the house where the lights will be installed faces south and without a huge amount of work and cabling, the photocell will also need to face south. I'd assumed that facing south was probably the best scenario however reading the instructions for the simpler NEMA photocell, I find the instructions state it should be positioned facing north or alternatively as close to north as possible, to avoid damaging the photocell. I can't see any reference to such an instruction in any of the more complex units.

Firstly, is this the case with all photocells i.e. whichever I decide to go with, do I need to try and position it somewhere else, or is it just these ones?

Secondly, why is this? What will be the impact of positioning it facing south? Will it be less effective or will it simply have a reduced lifespan? If it's the latter what are we talking? If it means it might break in a few years time rather than lasting forever, I can probably live with that, but if it's going to die as soon as we get a hot sunny day each year, I definitely can't My curious mind wants to know why this is stipulated anyway

 

[EFLImpudence]

NEMA is a US electrical trade standards association.

The National Electrical Manufacturers Association is the largest trade association of electrical equipment manufacturers in the United States.

Which product have you in mind?