[michmedclones]

Hey guys I have a quick question, I have an electrician coming over that I know and he needs to know the full load amps and voltage of my ballasts to get the right boxes and wires to run from my sub panel to my room. I want to run 4 1000w ballasts, I'm using these: https://www.hydrofarm.com/pb_detail.php?itemid=7627 Xtrasun 1000w mh/hps convertable ballast. I know I want to run 240v so I'm assuming that the voltage he needs, but I don't know the full load amps, I've read that the amp pull is 4.5 for a 1000w on 240v but I assume the fireup amp pull is higher and he wants to know that to make sure everything is kosher. If anyone can help me out I'd greatly appreciate it, I've tried to find it online and I'm having NO luck. One more quick question, for 4 1000w lights, fans, dehumidifier, enviromental controls, Co2 tanks, etc what size sub panel would you run? He was thinking 50-60 amps which sounds like more than enough but I don't want to have to change in the future. BTW its a 12x11 flower room.

Thanks guys

[Electrician]

I like to install 240Volt 1Phase 50amp subpanel in the room. It makes it very easy to add change/ loads in the future. Also 50amp MLO Load Center subpanels are cheap.

[michmedclones]

Awesome I thought 50 would be enough for 4 lights and accessories, thanks a lot.

If anyone knows about the amps I'd greatly appreciate it

[RomulusUSA]

Figure 18a for the ballasts at 240v, and maybe 10a for everything else. I'd look at a 50a sub, and a 30a or 2x20a circuit for the lights. You could get away with two circuits of 14/3 honestly, well within capacity. Then another 15-20a (or 2) circuit for the accessories.

My veg/bloom room has a 50a breaker (wired for 95a, not nearly pushing it so have yet to swap breakers in either panel), 1x20amp@240, 1x15a@120 and 2x20a@120. Word of advice for the accessory circuits - do 4 or more duplexs! I did 2/ea and wish I had more in some locations.

[avant gardener]

simple formula:
(watts/volts)x125%=amps.
this applies to single circuits as well as services and subpanels.

for instance, you want to run (4) 1000 watters on a singe 240v circuit, so:
4000/240=16.7 amps.

now add 25% to that figure to account for the extra load you'll draw when firing up:
16.7•1.25= 20.8 total amps.

you need at least a 30 amp circuit,
but long as you're pulling wire, i'd think about grabbing some 6 or 8 gauge wire and putting in more power in case you ever expand. it's much easier (read:cheaper) to do it now than to revisit it later.

figure the wattage on your other accessories and plug in the formula for as many circuits as you want to run. calculate the amperage (ermembering that most of these things are probably running on 120v), total them, round up, and you'll know how big a panel you need. again, i'd err on the side of a bigger sub just because you can. unless it's a long pull from the main service to your sub, the wire won't set you back too much either.

[Gray Wolf]

What AG said, but may I add?

A 1000 watt ballast isn't 100% efficient, so if possible look on the ballast name plate for actual amperage draw. The difference isn't huge, but it adds up.

Stagger your ballast and motor start ups, so as to not simultaneously spike your systems in rush amps.

Keep all of your ballast and motor loads, with high inrush current during startup, on separate circuits if at all possible. Look on the motors name plate for LRA (Locked Rotor Amps)amps.

Typically I design circuits at 80% load, to allow for voltage drop due to heat. What ever total amps I come up with, I just divide by 0.8.

In the case of 20.8 amps, 26 amps would be required to cover potential heat losses, so a 30 amp breaker would be adequate.

As already noted, what ever you think you will end up with is probably wrong, when you consider future possibilites, and the cost of wire and breakers is minimal to install a 50 amp sub panel.

Might I suggest that you also leave room for more breakers, for future brain farts?

[growshopfrank]

FWIW there is NO big inrush or spike with 1000w cap and coil ballasts period