400W MH bulb and ballast....how many amps on average?


I'm looking forward and contemplating lighting for my 240g (96x24x24).
My initial plan was for two 48" 2X250W+T5s Outer Orbit fixtures, especially since I already have one fixture. My ideal plan is five Hamilton Cayman Sun 400W HQI Systems with LED lights and Hamilton 400W HQI ballasts.
I'm not concerned about the electric bill, but I am concerned about the amps needs to run all these 400Ws.
On average, how many amps is required for a single 400W bulb/ballast? I guess I can contact Hamilton Technology, but I thought I'd throw it out there.
I know I have 20 amp circuits and the room has four available outlets, but I haven't checked to see if the outlets are on one or more circuits. I'll play with the breaker switches this weekend and find out.


that's easy, watts = volts x amps. volts is 120. 400 watts, that's 400/120= amperes. 3 amps. Most household circuits are 20 amps. But add in your pump(s). You should be fine. And modern circuits will trip near capacity. Only then will you need an electrician to rewire to a higher ampere rating. It's the gauge of the wire that determines the ampere capacity.
I run 3 MH, 1250 gph pumps, powerheads, VHO, and LEd, and have no problems. One thought, always a good idea to install a GFI outlet, of your circuit isn't already on one. Installation is simple, can buy the outlet at any hardware store, disable the circuit breaker, replace two wires and your done.
Hope that helps.


Active Member
We're running 3 x 400W MH's + actinics + pumps + controller +chiller etc and ended up putting in two dedicated circuits just for this tank (150g). Every so often one of the circuits gets tripped. I'm suspecting it's the middle MH that has a different ballast than the outer ones.
We'll be switching to full T5's in the next 2 weeks. We have no plans on keeping SPS in this tank like originally planned, so there is no need for the heavy lighting.