talk about your systems here- i want to know about your power distribution/setups

[Grant_VK5GR]

Karl,

I note you are in the UK - so I am assuming you are running 220VAC instead of the US 110V system. Here in Australia we also have similar (240VAC). This typically means that the current draw is less but the voltage is higher. The overall power load stays the same however.

I dont know about the UK, but here in Oz we have typically between 55 and 80A single phase feeds into our homes. Thats enough for about 13kW of load if you turn everything else off in the house (for a basic 55A feed). Going higher than 80A, and I would look at 3 phase if you could get it. 3phase 32A/phase 240VAC should be obtainable depending on your supply authority rules (the equivalent of 24kW of capacity or a 200A single phase 110VAC circuit).

The problems you may encounter however begin when you make your choice of lights. If you try to go the "energy efficient" route and base your lights on a lot of LED technology you can run into problems dimming those lights. The LOR boards dont react well to having too little load on them, and whereas in the 110V countries even smallish loads still maintain sufficient current load to prevent TRIAC misfire problems (which causes random flicker when you dont want it to), on 240V, the currents fall low enough to become an issue.

My solution (and that of a growing number of us here in Oz I believe) is to use a mix of DC and AC boards. As a result, my system here has about 32 channels of 240VAC with the rest running on a mix of 24 and 36V DC. I also then remote the controllers out into the yard to cut down on the length and volume of cabling that I have to support.

This has it's own problems because now I need to ship high current DC (up to 40-50 amps) out to the controllers for splitting/switching and distribution to the individual decorations. Your problems then move from distributing AC (and the safety/weather proofing aspects of high voltage AC) to then distributing DC and dealing with the ohmic resistance of the cables vs larger currents being transmitted. The impact of that is that controllers can interact with each other as DC loads are switched on and off due to changing volt drop. Why is this so you may ask? Cable resistance is a constant, therefore as current goes up, volts go down, hence brightness drops. This causes channels on different controllers to dim seemingly randomly due to voltage fluctuations caused by other controllers switching on and off through your sequences.

My solution was to run 3 DC rectifiers rated at about 60A DC each and feed only 2 controllers per long heavy DC cable feed (my feeds are about 20m long) with total loads around the 15A mark per cable feed. The DC feeds are fed out via 8 gauge cable. The result, volt drop is held to about 1 volt, which means that brightness fluctuations are not noticeable across the different controllers. After the controllers, the individual channel load typically doesnt exceed 30W (about 1.1A @ 28V) for 300 incandecent bud lights (less for LEDs). This also makes it easier to lay the longer cable feeds out to the decorations as cheaper lighter cables can be used fro that point on.

I have some details and photos on my construction pages http://christmas.darkeyrie.net/howitwasdone/construction.html which may help you out.

My suggestion for 240VAC countries is to think seriously about how many mains powered lights you use and keep them to a minimum, instead using low voltage DC for as much of your rig as you can. It's safer, easier to control and easier to interface to the more energy efficient LED lights available today. You can also deliver more light for less power, which is much better on your electric bill :-)

I am shortly going to make a video also of how I designed my rig. I'll post back here when it is ready (probably a couple of weeks time).

Regards,
Grant