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My understanding is that Warley club require Portable Appliance Testing of all mains electrical equipment with a layout /stand at their show at the NEC , and this is because of the requirements of the venue (the NEC) - everything that passed gets a sticker I believe. This is a test of the insulation/earthing. It is not a testing of the low voltage wiring on a layout - though if you've bolted an uncased mains transformer under the layout , you'll fail (And if anyone ever touches the thing while its under power they'll die by electrocution - uncased transformers are literally lethal)

I've been round this one, at some length, both with an electrician in the club riding a hobby horse (facing off with another electrician in the club) , and in an exchange on one of the websites with an anti DCC nut who claimed DCC layouts were fire risks and was visibly making up scare stories as he went along ( I recall he claimed that if you used dropper wires it would be unsafe unless you fitted an individual fuse to each dropper. ) Neither can be ranked among the more sensible discussions I've had, and I'm assured by folk who have spent many years working with electrical and electronic equipment professionally that both were talking rubbish

I've never heard of any suggestion that the low voltage circuits require certifaction or checking, though it's a good idea to ensure all wiring is rated adequetely for the loads carried. Quite apart from anything else, the thicker the wire , the less voltage drop you get at a given current, and voltage drop is a Bad Thing. The one area that does worry me is the suggestion often made that a layout can be converted from DC to DCC just by connecting up[ a DCC system and turning on all the section switches. What's widely sold as "layout wire" seems to be 1.3A rated; the typical DCC system pushes out 2.7A - 5A depending on brand , and I do worry about the implications . I'd argue that long wiring runs (eg main feed return, connections) should be at least 3A rated wire, or higher regardless of whether youre using DC or DCC

Gary
QUOTE It would not surprise me if in a few years time all model railway electrical wiring has to be certified by a qualified electrician prior to powering the system up. One advantage of DCC is that you don't need any!

The last time I looked under either the club project or my own little layout, there was quite a bit of wire actually . The wire free system was Exactoscale's Red Arrow, which involved rechargable batteries in the loco and an infrared control signal , and which seems to have died with Bernard Weller

I'd assume it was the mains side that caused the fire here - and one would expect it to be wiring on the workshop side or the mains supply. I believe it is now illegal to carry out mains wiring yourself - unless you are a certified electrician already
 

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Richard - don't blame Gary here , blame me.

I'm not an electrician , but the stuff in question comes from Maplins and is described on the packet, as 7/0.2 wire, 16/0.2 wire and 24/0.2 wire, figures of 1.3A , 3A and 5A being quoted on the labels in the shop

The stuff being commonly sold in the UK at shows labelled "layout wire" seems to be the lightest of these 3. If people are using this for main runs of wiring to sections on DC layouts(and I suspect some people are), then I have my doubts about simply hooking a DCC system up to a DC layout

On my own current small project , I've tried to use 16/0.2 wire for the droppers , though its a little awkward to solder neatly and conceal especially in the thin ballast that results with using SMP. There is a little 7/0.2 wire used where I ran out, and all pieces of track have their own dropper - longer ones have two droppers. Connections from bus to sockets for interboard cable and from NCE facia panel to NCE autoswitch device are 24/0.2 wire

Droppers are connected to buses which are taken from 240V mains cable (live and neutral wires) , which is solid core . The layout is 8'6" long, and the system used is NCE PowerCab - the transformer supplied is labelled 1.11A at 15V. I'm being prudent in case something capable of delivering 3A to 4A is ever connected

The current club project uses 7/0.2 wire for droppers , wired to power buses made from solid mains cable . The club chairman was talked out of demanding replacement of all dropper wires with 16/0.2 wire on health and safety grounds by someone with a professional electrical background

I don't think there are any of what you would class as "very large layouts" - the big perminent layouts in 100' x 30' rooms - in existance in the UK - certainly not DCC ones
 
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