Maxiswitch control units divert the electrical load from a timer to a heavy-duty relay or contactor. Seven units are available for servicing most requirement, from a Maxiswitch 10A 2 Way Relay to a Maxiswitch 26A 8 way contactor. As a guide, Match the switching loads to the correct control unit, for example 2 x 1000w Sodium power packs = 10A running current (Switching load) so a 10A control unit should be selected. Each four way gang has maximum load of 13A. Contactors Working out which contactor is for you for the safety and reliability a grower needs. Power ratings: - 250W = 1.3 amp - 400W = 2.4 amp - 600W = 3.1 amp - 1000W = 5 amp The contractor unit should be matched to the power the contractor is used for, so for 4 x 1000 Watt ballasts = a 20 amp unit should be used. Timers The use of an efficient timer is absolutely essential for the indoor or greenhouse grower. Timers are used to automatically turn on and off your lighting system. Indoor plants require from 12 to 18 hours of light a day and it is essential that timers are reliable. A failed timer can mean that lights remain on for 24 hours which will have a big impact on your power bill. It could also completely disrupt the flowering cycle of certain plants such as chrysanthemums, which require specific light hours to flower successfully. Ordinary plug-in timers can be bought cheaply enough at your local DIY store but they are not suitable for more than one or two lights and they can sometimes be prone to failure. For complete peace of mind, we recommend a mechanical timer of industrial quality, which can be relied on with confidence. Alternatively you can use relays or contactors which will divert the power load away from the timer itself. Hercules is a well-known contactor set, which is made up all ready to just plug in. These will be available from local Hydroponic suppliers. Power Consumption The amount of electricity needed to grow plants indoors can be surprisingly small and it should never be seen as a reason not to go ahead. The beginner is strongly advised to work out his power consumption before he starts, to make sure that his operation will be cost effective. A few figures have been included here as a guideline but you will need to check your local utility rates to see if they apply to you. Based on the approximate rate of 8p per unit, it will cost 38p per 12 hour day to run a 400-Watt light. This would translate to £34 on the average 90-day bill. If off-peak power is available and is used for seven hours out of the twelve, it would reduce that bill to around £25. WARNING Mains Voltage can Kill. The conditions in a greenhouse or growroom are generally damp and humid. Please take extreme care with all electrical installations. All timers, plugs, sockets and other electrical fittings must be placed well clear of any potential splashes. If you are in any doubt about wiring or any electrical matter, please call a licensed electrician. No timer included.