Normal household timers are not designed or rated to deal with the inductive power load used by horticultural lighting, There are 2 ways around this, you could go to your local Hydro shop and buy a contactor all built and ready to go along with a hefty price tag.
Or you can get yourself a suitable change over Contact Relay switch, this will only set you back a few £'s. A contact relay switch is required so that the timer turns on the contactor, which then turns the light on.

Almost all new growers will experience light failure. The reason for this is the contacts in these timers are not sufficient for the job. Household timers are rated for a RESISTIVE load, ballasts present an INDUCTIVE load, (a very large surge at switch on) this fuses the timer contacts together = Timer failure.

Q: What is a relay switch?

A: An electro mechanically operated switch.


What follows?

Complete instructions (including photos) on wiring a contact relay switch to replace your timer contacts in 6 easy steps


Q: What parts are needed and where can I buy them?

A: The following parts can be purchased at any good online electrical store i.e. maplin.co.uk rswww.com or a local electrical wholesalers such as City Electrical Factors

In my case I run 1 x 400w HPS, I know the INDUCTIVE load is 3.15 amps at switch on. Ask the manufacturers of your light for this info.

I have chosen a 230 volt, 10 amp contact relay switch from CEF (City Electrical Factor) reference number 6012-8230BP for the 2 pole 8 pin relay and 9020-BLKBP for the plug in base and is part of the MCG (Motor Control Gear) catalogues Finder range. This particular Relay switch has screw-terminals for easy wiring, and a push fit, easy mount base with numbered terminals.

You will also need a 3 way terminal block, 2 x 3 pin mains plugs, 1 x 3 pin female mains socket, 1.5 meter of 2 core mains wire, sharp wire cutters/blade, an electrical screwdriver, and a cross head screwdriver.

(optional:I housed my relay contactor in a waterproof ip65 housing at a cost of £12)

here is the tools and parts you will need
[attachmentid=29383]

How to wire a relay/contactor unit.

Note: mains voltage can kill you! So please exercise caution when wiring electronics of any kind!

1. Cut your 2-core wire into 4 measures the same length. Now pre-pair the wire ends, cut 2" from the outer sheath, then cut 1 cm off the inner sheath to expose wire. *Optional - solder all wire ends*
2. Fit mains plugs to 2 of the 4 pieces of wire, and then 1 of the remaining pieces of wire to the female mains socket.

3. Select one of the pieces of cable terminated with a mains plug, and connect to the relay base as follows: - Connect the live wire (Brown) to terminal 7 on the relay base. Connect the Neutral wire (Blue) to terminal 2 on the relay base. These connections are used to energise the relay coil. Now label the mains plug “Timer” (Plug 1)

4. Select the second piece of cable terminated with a mains plug, and connect to the terminal block as follows: - Connect the live wire (Brown) to terminal 1 on the terminal block (see diagram for terminal block numbering sequence). Connect the Neutral wire (Blue) to terminal 3 on the terminal block (see diagram). These connections are used to operate the grow room light (via the relay contacts). Now label the mains plug “Power” (Plug 2).

THIS DIAGRAM DOES NOT HAVE AN EARTH (EARTH CAN BE ADDED TO EACH OF THE PLUG ENDS BY USING THREE CORE ELECTRICAL CABLE INSTEAD OF TWO AND JOINING THESE TO EARTH CONNECTION IN THE WATER TIGHT UNIT TO INCREASE SAFETY)

5. Select the third piece of cable terminated with a female mains socket, and connect to the terminal block as follows: - Connect the live wire (Brown) to terminal 2 on the terminal block. Connect the neutral wire (Blue) to terminal 3 on the terminal block.

6. Select the final piece of wire and proceed as follows: -Connect one end of the Brown wire to terminal 1 on the terminal block, connect the other end of this wire to terminal 8 on the relay base. Connect one end of the Blue wire to terminal 2 on the terminal block, connect the other end of this wire to terminal 6 on the relay base. Note: under operating conditions both of these wires become live.
[attachmentid=29384]

7. Now take the relay unit and plug into relay base. (Plug 1) plugs into the timer. (Plug 2) plugs into a separate power socket. The female mains socket will supply power to your grow room lights.

The Principle of operation
When the timer switches on it will provide power to the relay coil, this in turn closes the relay contacts and bridges the terminals 8 & 6 on the relay unit thus providing power to female mains socket.
Total cost =£12. Time taken = 30min.
Total cost with watertight housing=£24 (as good as purchased contactors)
Total saving =£25-30
Total saving with watertight housing=£13-18



i hope this will be of help to all
:peace: the d.o.c[attachmentid=29385]

i followed this tutorial to make my relay, but i used the version on overgrow...... doc, are you skunkaroo on overgrow? (who did the tutorial there)
if you are, thanks, you saved me 20 quid, or a broken  timer

peace

~AurorA~

no ,i also got the details from O.G and converted it to be applicable to a U.K audience
a similar version can be found on my homepage where i thank Skunkaroo because although it was american based and a nightmare to track down the bits and pieces here,it was a real crop saver
unfortunalty i dont have a digi cam yet (will have to borrow mates again) so i cant post my own pictures of how the U.K components look yet ,but as soon as i get the digi cam again i will be able to show the whole unit as it should look in the waterproof housing  

peace mate
the d.o.c

Thanks for that d.o.c. Nice one m8

Very good thread d.o.c

Go on...build us one will ya...

i thought i would post the pics of the U.K components and how it looks


and here is how it looks with the wiring in


peace
the d.o.c

here is the whole thing ,ready to go


i would build them and send them as long as you buy the components and cover the postage (and £5 labour cost   )

hope this will help some new growers out there

  the d.o.c

£5 per half hour.....you're doing alright ent'ya....

D.o.c.....I will be your first customer...I hope you work to the same HIGH standards I do  
PM me with the full price and I'll sort it.

Hi d.o.c. I was wondering ,would the same 10Amp relay work o.k for 1 -1000w hps?Ta Orinoco...............

you would have to contact your manufacturer for the information related to the inductive load it produces at startup and buy a relay that comfortably will cope with the amps
as my light produces around 3.15 amps at startup (400w)
i reckon it would be touch and go ,
rough calculations would put the inductive load at around 9 amps plus with a 1000w on a 10 amp relay (and i like to have a few amps more than the light produces ,for peace of mind)

this is not by any means the real inductive startup load of your light and for safety and security i would contact the light manufacturers and ask the inductive load of the 1000watt light ,

i am sure you can buy relays with different capacitys and it wont be a problem finding a relay to fit
peace
the d.o.c

Quote

i reckon it would be touch and go

fek that mate...

I'll go to growell Dont wanna burn baby...

Heres a relay rated at 30A for £6.99

http://www.maplin.co.uk/product....=Finder

If you need bigger than that, you could go to a local electrical trade counter and ask for a contactor (these go up to 100's of amps)

Another thing...Most relays have more than one set of contacts. If you connect these contacts in parallel, then they would share the current flow...eg 2 sets of contacts rated at 10A in parallel would have a current rating of 20A

HTH

MrB

Thanks Bucket  
I'm on the case  
Orinoco

glad to help  

MrB

High there,


Nice, informative, article DOC, but one thing makes me wonder - Skunkaroo is from the UK, and his part list is from Maplins.

The relay and socket are JG54 and JG60.

I bought the parts from Maplins today and made a relay,as per Skunkaroo's instructions.


How come you thought the original instructions were aimed at an American audience?


It justs seems strange that you'd have such a "nightmare" sourcing UK parts, when the parts were all UK-listed in the first place?!


Mr.Bucket: the relay you posted is not the type required - follow the instructions and you'll have a fully working timer relay.


All the best,

Trichome

Hi Trichome

I know that relay wont fit the standard relay base. Spade connectors would need to be used. Orinoko Womble was worried that the 10A contact rating wouldn't be enough for his 1000W lamp. The 30A relay I suggested should easily handle it. You could use any bog standard timer with it.

Should have explained myself better  

thanks
MrB

DOC,

I don't know how I didn't notice the first time I read this thread, but you want to very careful! Going on the pictures you have posted, You have not used 3 core flex! It's extemely important to make sure all earth wiring is bound to a common point in the box. If a wire should come loose on your HPS, your reflector could become electrified! This and water in the area is asking for trouble! I am time served electrician so please heed my warning   By selling them without earth continuity you could be looking at a jail term if someone gets hurt

Not a sly dig at you mate, but electricity is dangerous stuff if not treated right  

Thanks
MrB

Mr Bucket, I was also thinking about what you pointed out, and thats whats stopped me from building one, although I would like too. Would it be simple to mod it with 3core so it was all nicely earthed? If some one could do this it would be greatly apriciated, and Im sure others will think so too. A definite build for me if done.

Thanks

Sorry for the delay Burnah, I didn't notice your reply.

Yes it's dead simple to mod the DOC's design. Just fit 3-core in place of the 2-core and connect all the earths together in the box. It would also be better to use a metal case and attach all the earth wires to a nut and bolt that passes through the case.

MrB

been away a while ,sorry about the delay

on my own site i state that the design is adapted to supplies i could readily find ,unfortunalty there is no maplin where i stay so i had to use a store most people could find

i did not adapt it to three core because i am not an electrician like yourself and i followed skunkaroos instructions with my parts ,although my cousin is an electrician and he inspected it and said as long as all my contacts and wires were screwed in tight it would not present any problems to me

although i will present your quandry to my cousin and see if he thinks i need to adapt further still
thank you for drawing this to my attention Mr B

the d.o.c

No problem DOC...glad to see your back

MrB

That was me

Built one for my 600W, works a treat, thanks DOC

Thanks for the updates people, Ill be making one of these with some 3 core wire then, hopefully all will work out ok .

hey the doc

Contactor??????

I have a normal timer from screwfix for my 250 hps and have had no troubleas yet, this is not a fire hazzard is it

electrics timers lights wiring this is not my fortey, i was happy laying bricks

all learning many thanks sj

If anyone wants a to switch a smaller current up to 16A
You can buy a Horstmann 425 Coronet Central heating controller (single pole mechanical type) from any good electrical retailer for about £20+
All you need to do is buy a 4 way extension lead ( about 5 meters length ) take the plug off and connect these wires into the output terminal on the unit . Just get another length of 3 core mains cable (13Amp length about 3 meters) connect it into the input terminal on the unit and attach the plug to the other end. Get a small peice of wood and screw the unti unto it.

You now have a 24 hour timer that can switch up to 16A.

Hi D.O.C.
I read your timer relay thread with quite a lot of interest as I'm a newbie to this I was wondering about the surge taken, amperage wise, when cranking up HPS lights.
I also noticed that on your finished product you have a nice mains cable protector/clamp leading into the casing. I mention this as on another D.I.Y project on this site, converting the low bay type hps light, the mains cable is going through a hole in the metal casing with no grip/protection or anything, i feel for safety sake a rubber grommet should be used at least.
I only mention all of this as a safety precaution to anyone out there attempting anything like this as volts JOLT but amps KILL!

Hi all,

I found this post very informative, and thought I could add to it by supplying a specific part number, for a timer switch that is rated at 13A (Resistive) 5A (Inductive). Maplins sell one for £14, and is part number VJ58N. They do mail order too, so if you dont have a store near you...

My first post!!

Hi D.O.C and everybody else.
A mate of mine has been messing around with Diodes and reckons that a industrial type IE one from a street light is able to cope with the Inductive load
If thats the case
Im not a electronics buff
but would a Diode negate the need for the manual switch
it could be fitted between the timer and the power out side
a heavy duty diode of that type is about £1
if itll work then u cannie get no cheaper than that can u?

Hi wugahuftamump,

I'm in no way an expert either, but I think a diode only allows electricity to pass one way?


Flux.

Bottom of the following page :

http://www.theheadgardener.net/catalogue/a..._Relays_35.html

QUOTE

Trac Timer Can switch up to 400W without a relay. Price:  £15.00 [22,14 Euro]

Hi,
If you are like me and need heat sometimes when the lights are off
Why not re-wire your contactor to have another socket , a NIGHT one ?

The Night socket is where u plug in your heater(s) and it only gets
switched on when your lights are off .. handy for propagators too.

To expand all you need is another length of 3 core cable and a socket to
wire it to.
The diagram is pretty clear but any questions just post

Night and day power strips is a great idea shad, looks like a rats nest the way I've done mine. Opens up a world of possibilities, hydro guys can have 2 heaters in the res, different fan speeds etc.

PRS (Dale St. Liverpool) have surplus (but new) 10A relays at £2.50 and £3. One type needs a base, the other doesn't and has spade connectors. They're controlled by 12v, so a cheap option if you've got a 12v mains adapter going spare. 3 contacts, so 30A possible.
Don't know if they'll do mail order, but I'll ask if anyone is interested.

would i need a contractor for this:
http://www.screwfix.com/app/sfd/cat/pro.js...=48734&id=10570

thank you please

rocky

just a crazy idea,but how about wiring a small 15w lamp between neutral and pin 5 of the relay,put the light outside the grow room so you have a visual indication of when its dark.
Also as a rough guide if your unable to obtain the start up current from the manufacters, multiply the lamps wattage by 1.8 and use this figure to calculate the current rating required

A very usefull read ... thanks to everyone who has contributed. I hopefully will be buidling a contactor soon ... I didnt get one for my 250w HPS as I had been informed by some that it was only really necessary if it was OVER 250w ... and by others that I should get it to be safe.

The short version is I was a fool ... the timer blew, and now I have to switch on the lamp about 6am in the morning ... every morning

Thinking of giving the building a look into ... looks fun and cheaper than buying.

are any of these ok??????

The link isn't working BD, but if it is part JG54, then




Wilbur

link not working?? try this

they havent got JG54 in stock, and the thing is, I need a contactor NOW (i have a half flowered clone under a 70, and want to get it under the 250 ASAP)

its QC81C im looking at, will any double pole 10a 230v 8 pin relay do???

there are two bases too, would it be a PCB or a DIN socket i want???????

does anyone know anywhere else i can get cheap relays online????? ive been searching ages but cant find anything (all i can find is links to bloody search engines)


[B-Dr]

nice one TMH

one shop tried charging me £10 to deliver a couple metres of mylar

I know this thread is old but here goes, would i need a contactor to run a 125watt enviro?

easy elzzar,

no, you wouldnt need a contactor for an envirolite..they are only used for HPS/MH lamps.

hope it helps

BB