Timeguard 24hr Immersion Timer and 70W HPS light?

[eveares]

My granddad wants a 70W HPS lamp fitted under a big tree in his garden and so I have gone ahead and order the required parts.

The key parts being a TimeGuard NTT01 24hr immersion timer, a Photocell, and of course the 70W HPS light fixture. Wired like so: Fused Spur > Timer > Photocell > HPS light fixture.

Now I did not read the timers manual before ordering as to me they are simple devices and is little to gain from reading the manual - I was clearly wrong as in the manual it states it is unsuitable for use with discharge lighting, which of course the listing for the timer on TLC's website did not mention.

Will the inital inductive startup load of the 70w HPS fixture really cause a problem with the contacts in the timer; now I don't know what the inital current spike is when a 70W HPS lamp starts, but I hope it is less than 6 amps what is the inductive current rating of the timer.

This article suggests the start up current for a 70W hps lamp at 230v is only 0.63 Amps, but that may be for the non-inductive load or the load just after ignition.

Regards: Elliott

 

[bernardgreen]

It is not quite that simple. HPS lamps must be allowed to cool down for at least 5 minutes after being turned OFF. Turning them back on before they have cooled down can result in damage to the lamp. Provided the photocell has a delayed response to changing light levels that ensures at least 5 minutes OFF time this cooling down period may not be a problem.

If you use a plug in type relay controlled by timer and photocell then it will make it easier to replace the relay when its contacts are damaged by the lamp

 

[ban-all-sheds]

in the manual it states it is unsuitable for use with discharge lighting, which of course the listing for the timer on TLC's website did not mention.

 

[ericmark]

Should the timer and photocell not be powered in parallel then output from photocell should go through the volt free contacts of the timer, or when timer switches on the photocell will likely power up the light under test mode for around a minute.

 

[bernardgreen]

Should the timer and photocell not be powered in parallel then output from photocell should go through the volt free contacts of the timer, or when timer switches on the photocell will likely power up the light under test mode for around a minute.

Yes. permanent power to tjhe photocell.

 

[eveares]

HPS lamps must be allowed to cool down for at least 5 minutes after being turned OFF. Turning them back on before they have cooled down can result in damage to the lamp.

Never knew that, although I know the ones with external ignitors generally take a few minutes to re-ignite after being turned off, and the ones with internal igniters take several to tens of minutes to re-ignite after being turned off.

BAS, re-read what I said; the listing does not mention it is unsuitable for discharge lights, however the linked manual on the listing does.

or when timer switches on the photocell will likely power up the light under test mode for around a minute.

That will be the case as the the photo cell will be switched by the time switch, Not that big of a problem though. I could also try and source a NEMA compatible photocell that does not automatically switch on when first powered up.

Will a 70W HPS lamp really pit/weld together the timers contacts? How is a small discharge lamp different from a =< 6A inductive load?

 

[bernardgreen]

Will a 70W HPS lamp really pit/weld together the timers contacts?

I can't say for certain either way if it would pit or not pit the contacts. My philosphy is that it is always worth adding a relay costing a couple of pounds to protect a more expensive item such as a timer or photocell

 

[eveares]

Edit: Just converted the timer to a voltage free one by removing the neutral link between N In and N Out, and separating the Line in for the motor and Line in for the contact.

The photocell can now be permanently on what will feed the timers contacts.

 

[EFLImpudence]

Won't the timer still just switch the light - which is what it's not supposed to do?

 

[ban-all-sheds]

BAS, re-read what I said;

I don't need to - I know what you said.

the listing does not mention it is unsuitable for discharge lights, however the linked manual on the listing does.

It's all one and the same thing. Don't try and make out that it doesn't contain all of the information you needed to know because you couldn't be bothered to read it.

 

[eveares]

It's all one and the same thing.

When I said listing, I was clearly talking about the web page alone excluding the pdf attachments.

Won't the timer still just switch the light - which is what it's not supposed to do?

Yes, but now the photocell will feed the contacts on the timer rather than the contacts on the timer feeding the photocell.

Also, I find it strange that the 70W HPS light has no power factor correction capacitor inside, just pre-wired the flex onto it and could not see one inside the unit.

 

[Iggifer]

now the photocell will feed the contacts on the timer rather than the contacts on the timer feeding the photocell

Do you have a switched live and a permanent live at the timer then?

 

[deadshort]

Will a 70W HPS lamp really pit/weld together the timers contacts?

I can't say for certain either way if it would pit or not pit the contacts. My philosphy is that it is always worth adding a relay costing a couple of pounds to protect a more expensive item such as a timer or photocell

I agree with Bernard this is the better option.

DS

 

[ban-all-sheds]

When I said listing, I was clearly talking about the web page alone excluding the pdf attachments.

You should stop using TLC, and start shopping at Screwfix.

Because they also sell spades, and you'll find you can dig much faster with one of those.

 

[eveares]

Do you have a switched live and a permanent live at the timer then

There is a Line and Neutral for the timer's motor, and a Line and Switched Line for the switched contact.

You should stop using TLC, and start shopping at Screwfix.

Because they also sell spades, and you'll find you can dig much faster with one of those.

Bit of topic init BAS, I already have a spade thanks.