Fun with mains electricity

I didn’t get anywhere near as much done this weekend as I’d planned (thus proving once again that my estimation skills are poor), but I did get some useful work done on the power cabling for the console interior.

There are several devices within the console that require mains power: the two PSUs for PC1 and PC2, two monitors, the power brick for the tablet PC3, the power brick for the UMPC PC4 (via an extension into the pedestal), a USB hub and a network switch. And that’s just what I’ve come up with so far. All of these need cabling, and I can’t just let the cables float about within the console interior however they like. That would be an invitation to foul the controls or circuit boards yet to come. So clips and ties were the order of the day.

When I originally planned the power supply, I had intended to remove all the plugs from the equipment and plumb them directly into the main power line via connector blocks (and, of course, individual fuses – don’t think about joining mains-level wiring together without an appropriate fuse on each spur, unless you like the smell of burning electronics), and put the lot into a junction box to keep it tidy and above all, safe. I can’t stress this too highly – if you’re working with mains electricity, you must be very very careful.

Once I got into it, however, I realised that this would make life difficult for me when fuses blow, as I’d have to open up the junction box and fiddle. I decided that I could get by with a couple of trailing sockets. I settled on two 4-way extensions, dirt-cheap from B&Q. These are individually fused, of course, which makes sure that you can’t exceed the recommended 13 amp draw from a single mains socket. I mounted the extensions inside the console, thus:

Extension sockets in place inside the console

Extension sockets in place inside the console

(Note some cable clips are already in place to hold cables where they need to be – more clips will be put in later to define proper cable paths.)

I also made up some kettle leads to length, to avoid too much trailing cable. This is not difficult, although fitting the kettle-end plug is rather harder than a standard mains plug, and I usually solder the terminals for convenience’s sake. I also bought some right-angle kettle sockets to use with the leads to the two PSUs. This avoid the leads needing to stick out at the rear, which could foul them against the wall when the sim is in place. You can get these from Maplin at relatively low cost (<£3 each).

I then needed to join the leads from the two extensions into a single lead. I will use a proper junction box to do this in the finished sim, but for speed and convenience of testing I joined them temporarily with a simple plastic terminal block. If you’re going to do this sort of thing it’s critical that you understand the safety precautions you need to take. Always use terminal blocks and cables that are rated for the amount of power the circuit will handle (in this case, up to 13 amps). Smaller blocks designed for joining bells or 12v DC wiring will melt if enough power is put through them, and upon melting will most likely create a short which might start a fire (assuming it doesn’t trip all your home breakers first). Remember that the metal parts of the terminal block will be at mains voltage carrying several amps, so make sure there’s no way your flesh can come into contact with them – for preference, put a decent amount of electrical tape around a temporary join like this one, and for a permanent one you need an enclosure or junction box.

Two power cords joined into one

Two power cords joined into one

(This shot was taken before I put copious amounts of insulating tape on it.)

To finish off this phase of the cabling, I need to put lots more clips in place to guide the cables around the interior, shorten a couple of mains cables, and put the junction box in place. I’m installing a kettle socket into the side of the console so that the sim can be plugged in using a standard kettle lead. More on this in a later post.

I didn’t get around to my yoke-extending work this week, but the extra time has let me re-think a few things about it and I will need to order some more parts from RS Components before I can begin the work. A task for next weekend.