Editors safety note:
Skunkaroo's instructions below, failed to include a common
ground.
It would be much safer to use three conductor cord so that
a common ground could be incorporated into this project.
Tie all the grounds together using either a four post
terminal block instead of the three post block skunkaroo
used below, or else tie all the grounds together using a
large wire nut. It would also be benifical to tie this to a
dedicated ground close to the grow, this can be as simple
as a piece of pipe or ground rod driven in the earth with a
piece of #8 tied to it.
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 $$ ã. 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 this 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.
What is a relay switch?
An electro mechanically operated switch.
What follows?
Complete instructions (including photos) on wiring a
contact relay switch to replace your timer contacts.
What parts are needed and where can I buy
them?
The following parts can be purchased at any good online
electrical store ie maplin.co.uk rswww.com
In my case I run 1 x 400w HPS, I know the INDUCTIVE load is
3.15 amps at switch on. Ask the manufactures of your light
for this info. I am also running 5 x PC fans and a 1 x PC
power supply unit. I have chosen a 240 volt, 10 amp contact
relay switch from maplin code JG60 and JG54 this particular
Relay switch has screw-terminals for easy wiring, and a
push fit, easy mount base.
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.
Wiring a relay switch.
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 2Ԡfrom 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 ԔimerԠ(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 ԐowerԠ(Plug 2).
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 propertys both of these wires become
live.
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.
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 and 6 on the relay unit thus
providing power to female mains socket.
Total cost = ñ0. Time taken = 30min. Total saving =
ò5-30.
Last cannabis grow log changed: 19:18 - Dec 12,
2009
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