Timers and Light Management Units

[silent-toker]

Hi all

how many lights can i run before i need a light management unit?

 

my 2x 400watt HPS are blowing a HPM heavy duty timer so that sort of answers my question but i was using the same kind of timer on a 1000watter last time round with no worries??

 

surely i dont need a LMU for 2x 400's, the HPM timer is designed for spa/pool motors,heaters etc and should handle 10A:scratchin:

 

thinkin of maybe adding another 400 later on so a LMU might be the go, but what about a heavy duty timer for each light, could stagger the start ups that way? would be much cheaper that way, any advantages a LMU has?

 

What are you guys using for multiple lights ?

[SukonmiSkunk]

have you got the same timer for both lights??? use a seperate timer for each light... they might only draw 2-3 amps when they are running but on startup they draw a considerable amount more.. also have them come on 15mins apart... timers will have 15min increments...

[Shithappens]

Some digital timers can actually be modded to allow better life expectancy

 

I got some $20 digital timers and opened them up to find they drive a relay so i went allong to electronics shop and got a bigger relay and replaced the one in it it also allows me to move the control panel away from the switch with only 4 wires

 

no hassles anymore!!!

 

If i can find a cheap australian wide available one with a decent relay access in it ill do a walk through on the upgrade with protection and maybe a surge guard circut to boot

[EntyMan]

What Sukonmiskunk said. Although if you only have two 400w lights (on separate timers) you probably don't need to have them come on at different times. Your circuit breaker at the house switchboard, or overload protection on a powerboard, will let you know if you can. If the breaker/overload switch doesn't trip when both lights come on at the same time, then no problem. If it does trip, then separate the on times by a few minutes, and reset the breaker/overload switch.

 

If you are going to modify timers like Shithappens did, be damn sure you know what you are doing. Very easy to make dangerous mistakes with electrical wiring.

Edited August 21, 2006 by EntyMan

[Luke Skywalker]

2 x 400w lamps should only draw something like 4.6 amps when both running, and they'd pull a maximum 6 amps together if they were started at the same time.

 

Digital timers are available with 30amp contacter/relays, and are a little more expensive for it. It's worth spending the $ to get a timer with a better relay and never have it fail.

 

So yeah, you could run two lamps off one good timer through a powerboard, (never use double adaptors, they're evil things) but if you've got the space run them separately on different timers and you'll spread the load. 5mins difference between lamp startup times usually gives enough time for the load to drop to a better level. If you're running many other items on that same circuit though you could have probs.

 

Add up all the electrical devices which are being used on that circuit. (you can tell which circuit is which in a house by shutting off individual ones at the power box and seeing which powerpoints work.) If you only have one circuit for the house you could be pushing 10amps if you run other things like tv's, heaters etc.

 

But if you dedicate a 10amp circuit in your house, (some of us are lucky enough to have 15amp circuits. ) to the growroom you shouldn't have any problems.

[Stoney]

i just use an ordinary timer and that runs me 2x400w and me fans all good so may just need to get a better timer

 

cheerz

[silent-toker]

Thanks for all the replies guys.

i was running both lights off the one timer when it blew so i took that one back to swap it and bought another at the same time($25). so got a timer for each light now, but not staggering the start ups- will do that if i add the third light tho, so far so good

[silent-toker]

well that didnt last long did it!

one of those timers has tripped out and now got both lights running off the one timer again

not much faith in that so checking it switches on/off each time, it sucks to discover the lights are on 4hrs after they shoulda turned off happened 3 times now!!

 

can anyone recommend a reliable timer? What brands are you guys using?

[Gazza2001au]

the reason the timer worked with the 1000watter and not with two 400 watters is the 1000watt starts up at 3amps finishes somewhere around 4.5amps i think cant remember and each 400watter starts up at 2.8amps each 5.6amps total startup its to much for cheap timers some will work but there to many on the shelf these days could be costly trying them all i know the HPM digital timers from bunnings work for single lights i used one on a 600 and 1000 but they cost $20-$30 and you'll probably want 2 so your better off going into your local hydro shop and buying a digital timer with a 30amp relay this will run both of ur lamps off the one timer cost inbetween $40-$55 the fella from hydrocentre reckons he ran 2x1000's and 3x600's off one of these without any problems it'll be a cheaper option than LMU's Edited August 28, 2006 by Gazza2001au

[silent-toker]

the HPM timers are meant to be heavy duty and i had one for each light, thought i would be alright

nevermind they have a 5yr guarantee so will just take them back to mitre 10 and get my 50 bucks back

 

my local hydro shop dont have those digital timers, hes tryin to tell me i need a LMU for $200!!

think ill try around!! thanks gazza