A ballast is a large box containing an electrical transformer and other circuits required for the normal operation of high powered lighting. Ballasts are available with or without internal timers. This allows automatic switching of lighting, allowing plants to receive regular lighting cycles. To simulate summer, this is usually configured for 18 hours of light every 24 hours. To simulate autumn (harvesting time), this is usually configured for 12 hours of daylight every 24 hours. Typically, the daylight cycle is set to occur at the same time as daylight outside, so as not to confuse plants if the growroom is not lightproof. It also allows natural light to augment to light received by the plant.
It is not necessary to purchase a ballast with its own timer to ensure that plants receive light on a regular basis. Instead, an external contactor relay can be used. A contactor relay provides high current switching not found in domestic mains timers. The relay is used in conjunction with any timer, although the relay ensures that the high current does not destroy the timer. The timer merely provides enough current to switch the relay and the current for the lighting is taken directly from the mains supply.
The separation of relay, timer and ballast function can be a godsend when attempting to determine problems with high current electrical systems. Simply remove timer and relay to test operation of ballast and lamp in isolation. It also allows the selection of mechanical or digital timer, and allows the upgrade to fully automated growroom control. There is nothing unreliable or inherently wrong with integrated timers in ballasts, and the combination will save you money. It is merely the fact that unnecessary intergration of mechanical components is tempting fate. For this reason, we recommend the purchase of separate ballast, digital timer and contactor relay.
Please note that the size, colour and specification of ballasts may vary, although this does not affect operational parameters of the equipment. All ballasts sold by Esoteric Hydroponics will match or exceed the specification of the ballasts depicted here.
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