Timer
The following information documents an electrical circuit which requires a relay operating at residential AC voltage, so the work should only be undertaken by qualified personnel familiar with and working to the electrical code requirements for the country where this circuit will be used. Author assumes no responsibility for how this information is used, accuracy of diagrams, or consequences of its use.
OK, that was the disclaimer, but seriously, while this is an extremely simple
project for an electrician or most people with an electrical background, it
is not as easy as changing a switch or a receptacle for the average person.
Except for the relay, all the parts are available at your local home renovation
centre. The relay should not be too hard to find, and would be available at
industrial electrical supply shops (and most do sell to the public). Some of
the details are country specific, (I'm in Canada 120Vac), but are easy to adapt
to 220Vac operation by scaling up the component ratings. I'm not an electrician,
so I can't tell you how code compliant it is for Canada, never mind for your
country. I do have an electrical engineering background, so I can make stuff
work, and it looks pretty safe to me (it's been running about 2 years now).
This page documents the wiring to a single 66 gallon aquarium. I brought in
a dedicated 120Vac circuit and with electrical boxes and components, I added
GFI protection, 2 household plug-in timers for lights and one switch-like household
timer for shutting off heaters & filters for tank maintenance. An external relay
was needed to flip the operation of this last timer. Conventional timers turn
something ON for the time set on the dial. We need the filters & heaters to
be normally running, so our delay-timer must turn devices OFF instead, for the
desired time.
Since your interest might only be the delay timer, or the GFI power centre, I've tried to document the project clearly enough so that you can just take the part that you are interested in. Be sure to select components which meet your local power requirements for switching the loads on and off. My heater and filters were 260W max. The selected DPDT relay should be rated for the maximum current being switched, and have a coil which corresponds to your local voltage (120 or 240Vac). Drop me an email if you think that you have a really easy question for me.
Referring to Figure 1 below, this just happens to be the configuration which
worked in the space I had in my last project. The NEMA receptacles used in North
America allow you to snap a tab on the sides so the plugs operate independently.
I took advantage of this so that I could have my light timers (Circuits B in
Box 2, 3 & 4) running horizontally below my heater & filters (Circuit C, controlled
by the delay-timer).
Figure 1
Referring to Figure 2 below, accessories are all shown installed. I left myself
3 spare outlets. My main lights are four 48" 40W tubes, and my change light transitions
between total darkness and total brightness with a 40W incandescent bulb. The
change light operates about 15 minutes twice a day.
Figure 2
Figure 3 shows the wiring diagram. I didn't show all the ground wires. If you need to know how the grounds get connected, perhaps this is too ambitious a project to try ;~).
Figure 3
I've included a photo of the installation. Note that the light timers are not installed exactly as diagramed. Accessories which always have power can be installed anywhere in Circuit A or Circuit B.
Installation Photo
Note to electricians and electrical engineering types. I know the schematic could
be reduced so that less physical wires were needed by making better use of the
neutral paths. The DPDT relay could also be replaced by a SPDT relay switching
only the live leads instead of the entire circuit. The reason I chose this layout
to document, is that it's more fault tolerant, and by keeping the switched and
non switched circuits physically separate, easier to troubleshoot.
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