Controlling lights with a Relay and a timer

[ruet]

I'm setting up my seed starting shelf in a large crawlspace which has a 5 ft fluorescent fixture which I'd like to use as a light source on a timer. The problem I have is that the fixture's wiring is completely inaccessible behind a brick wall.

What is accessible is the switch, which I've managed to take apart (with power off of course — I'm too young to die!)
Pressing the two wires that went into the switch box together (wearing non-conductive gloves) makes the light turn on, so it looks like I need a relay and a timer to achieve full lighting automation this year.

My problem is I have don't know which relay to buy:
I figure it needs to be:
220V (voltage in Spain)
AC relay, not DC (I don't have many wall warts to convert to DC, and none of them give 5v output, which seems to be what the DC relays need)
2-4amp minimum (two tubes, each fluorescent is maybe .75 amp)
Normally Open? When voltage is applied from the timer it completes the circuit and the light turns on.


I've been poking around ebay as there are no electronics stores near me, but when sellers mention specs such as DPDT, SPST, number of poles, etc... I'm in over my head. Any electrical wizards out there that could shed some light here? What would you use? Should I just break down the brick wall?



Thank you!

[PaulF]

I know there are electrical wizards on this site; I am sure your switch/timer problem will be solved.

If your light fixture is stationary, I anticipate you will have a movable platform for the seeds. In order for optimum plant growth and health, the seedlings need to be a couple of inches from the light source. As the plants grow, the platform needs to be lowered to maintain the proper distance from the light. How will you be doing that?

[ruet]

I've removed the protective cover on the fluorescent lights and placed this on an IKEA EINA nightstand, which has peg shelf supports. After removing the top shelf portion, the max height of the middle shelf is perfect. As the plants grow, I drop the shelf 1 peg at a time as far as need be. The nightstand has wheels which is also nice. Will post pictures of the final product.

[dcarch]

I don't understand why you need any relay for such low power requirement.

Just get a timer that you can plug in an outlet and plug you light fixture in the timer you will be in business.

DPDT, SPST meaning double pole double throw, and single pole single throw, etc. Relays can work with Ac or DC. Your problem with doing it with relay is that you also have to have grounding done properly.

dcarch

[amideutch]

Ruet, I think this is what you are looking for. There are two types and I will give you links to both. If you need help getting them let me know. With these you can remove your existing light switch and replace with these. The second link is the wiring diagram for the first switch and should be the same for the other. You need to check the existing switch to see if it has both line and neutral present. Get an electrician to check for you and show him the links I sent you and maybe he has something similar. Ami

http://www.conrad.de/ce/de/product/6...ALTUHR-WEISS-T

http://www.produktinfo.conrad.com/da...sschaltuhr.pdf

http://www.conrad.de/ce/de/product/6...NZEITSCHALTUHR

[simmran1]

Dcarh is right, you really don't need to add any relay to complicate the circuit.

Your wall switch is a SPST, which means it has an on & off. (You don’t need to get to get too concerned with that lingo).

I’d assume this is an end of the circuit situation, where this switch only controls this one light.
What I’d do is (with the power off) put the wall switch back together-, then take the wiring out of the light.
Add another outlet near the light. Box and typical outlet should be available locally. Run those wires into the new outlet and connect
What you’re doing is making the existing switch, (the original wall switch the master contol).
Then get an Intermatic timer HB114c and plug it into the new outlet. Re-wire the light with new wires and make the end a male connector, (plug) like you were plugging into any 220v outlet. Your light then plugs into the timer.
This timer has 2 offs and two ons, but the settings can be so that you have basically one off/ one on.

[amideutch]

I think what ruet is saying is the light fixture is hard wired into the walls and the only way he can control it is either the wall switch or the circuit breaker. Now if he wants to disconnect the house wiring from the fixture and wire an extension cable from the light to a plug and then plug the light into a wall socket timer, yes that will work. Or they have timers that will fit in a breaker box and if the breaker only controls that light he can do it that way or am I missing something. Ami

[ruet]

Thank you Ami, simran1 and dcarch!

Ami was correct in his understanding, the light fixture is hardwired into the walls and on top of that, accessing the cable was difficult. I hadn't considered taking apart the fixture though! Upon closer inspection it looks quite doable, all I need to figure out is how to drop all 5 feet of bulb delicately. A pile of pillows should do the trick.

Thank you very much.

[Vince]

Why not just flip the switch and run the fluorescent 24/7?
Never hurt my seedlings, actually seems to help.