basic power questions and calculations


Full time elf
Feb 18, 2011
Mount Tamborine, Qld
Hi all,

Still slowly progressing towards this years display as time ticks on.......

Was hoping to check a few things with the brain trust.

In the past I have managed to get away with most of my display(up to 35 BigW strings) running off a single 10A domestic power point - but this year is a bit bigger, but not in the league of the serious displays.

I have six LOR DC controllers and they will be pretty close to fully populated with BigW LED strings(96 channels) running at 30V, so that's the basis for what I'm looking at.

Using a highend draw of 200mA for each string that gives me 19.2A draw (96 * .2A).

I have three 350W-27V PSUs dialed up to 30V, at the moment I plan to use two of those, each powering three controllers and 48 strings(9.6A).

To get watts, I calculate voltage(30) by amps(9.6A or 19.2A):
One controller: 30V * 9.6A = 288W
Both controllers: 30V * 19.2A = 576W

So it looks like each PSU should handle three controllers and we are just slightly over 80%(280W) of what each PSU can handle.

Does that look reasonable?

Next problem is will it all run on a single domestic(10A) circuit or am I better off getting a dedicated 10A or 15A circuit set up?

Each PSU states max draw of 4A at 240V, so I should be OK - even on max draw(which I won't be), I should still be at 8A or 80% of a regular domestic circuit and still headroom for other appliances......

Does this look OK or have made a hash of the power requirements?



I love blinky lights :)
Community project designer
Dec 27, 2010
No issues at all running off 1 power point. 1 point can supply 2400W and the power supplies are really likely to only be a little over 1A at full load.


Full time elf
Community project designer
Jan 2, 2012
Eastern Melbourne
You will be fine running them off a 10A circuit. You can do similar maths to what you did on the DC end on the AC end.

For your reference, the math:

You worked out max 576W of DC, take into account the efficiency of your power supply (let's say 85% for this example). Your AC power is 576 / 0.85 = 678W. Divide 678W by the voltage and you get 2.8A total on AC.