Wiring for 5amp DCC system

[disco-dave]

I'm currently building a layout in the loft and and will have a large run that circles the loft twice. I was looking at getting the nce power pro 5 amp system and have a question regarding wires.

 

I intend to have a bus that runs underneath the layout with dropper wires from the rails to the bus. My concern is the dropper wires from the rails to the bus. What thickness of wire do need to handle the 5amp system. Do I need the same wire that runs underneath for the bus, or can it be smaller less intrusive? How do I know what thickness of wire I need?

 

Any help or points in the right direction appreciated.

[Dagworth]

For the droppers from the rail to the bus you can use something like 7/0.2mm flexible wire available from maplins and other suppliers.

 

For the bus use something quite a bit heavier, Ravensclyffe uses 1.5mm solid single copper wires but that's because it's what I had. The wires are fixed under the boards and do not move so no risk of breakage, they are fixed into lengths of 'chocolate block' terminal strip at each end of each baseboard with 1.5mm flexible wires going to the bus connectors from the terminal blocks.

 

I'd recommned 1.5mm cross section wire as a minimum for a 5 amp system. When you've finished wiring do the coin test at various points of the layout, put a coin across the rails and make sure that the command station trips out. This proves that the wiring is heavy enough to carry the required current.

 

Hope that helps

 

Andi

[disco-dave]

Andi, Thanks for that. I've got some 7/0.2 wire, but wasn't sure it was the correct wire to use. It just seemed too thin for 5amps, but then my understanding of electrics is not good. That's put my mind at rest. Cheers.

[BR60103]

The dropper wires should only have to carry current for the trains in the immediate section. If you have multiple droppers in the section (between insulated joiners), you effectively have a bigger wire, provided your joiners are tight. If you are modelling a US train with 5 powered diecast diesels, you may want a little heavier wire.

[RedgateModels]

can you get your hands on some Cat5 network cable? (if not pop round after work and I'll let you have some) - perfect for droppers once the cores are stripped out of the cable, you get brown and blue as well which will match your domestic mains wiring cable you use for the bus ......

 

 

[beast66606]

Or buy alarm cable ... same advantages as Redgates tip

[Crosland]

Andi, Thanks for that. I've got some 7/0.2 wire, but wasn't sure it was the correct wire to use. It just seemed too thin for 5amps, but then my understanding of electrics is not good. That's put my mind at rest. Cheers.

The droppers can be much thinner than the bus because they are (should be!) very much shorter, just a few inches.

 

The thinner wire has a higher resistance per unit length than the bus wire, but you are using very short length and thus not introducing excessive resistance into the circuit. It then follows that any voltage drop in the droppers will be minimal.

 

During normal operation the droppers will only carry current for whatever is on the section of rail they connect to. Unless you're into huge US style lash-ups it's probably only one loco, two if banking.

 

Once you've wired everything up, do the screwdriver test. That is, put something across the tracks to creat a deliberate short circuit and check that the booster shuts down. Repeat at lots of points around the layout.

 

Andrew Crosland

[Ian J.]

Personally I use 10amp fuse wire for the droppers on Sayersbridge. I saw the technique used by a member of the Wimborne Railway Society (whose name escapes me right now). He soldered one end of the fuse wire to the rail, then dropped it through the hole in the board to wrap it round a brass screw on the underside of the board. The wires for power were then soldered to that screw. Seems to work very effectively.

[disco-dave]

Thanks for all the advice. Where can I get 1.5mm solid single copper wire?

 

What something like this do the trick?

 

http://www.rapidonline.com/Cables-Connectors/Equipment-Wire/Wire/Tinned-copper-wire/62485

[Brian]

Thanks for all the advice. Where can I get 1.5mm solid single copper wire?

Its normal to buy 1.5mm T & E cable and then strip off the outer grey sheath leaving the brown and blue wires to be used as the bus. If wished the former bare earth wire can also be run around the layout and used as a common return for items that are not DCC controlled - Street, platform & building lighting etc

 

You can obtain 1.5mm cable from Wickes, B & Q etc. These stores sell it in pre cut lengths of 7.5Mtrs or 10Mtrs etc or 50Mtr drums.

Example....Wickes 1.5mm

[RedgateModels]

Hi mate, I've got a reel of T&E in the garage, how much do you want? - cores are red and black not blue/brown ....

[disco-dave]

Cheers everyone. I've actually got some in the garage (unused of course). So I'll take a look at that and see how much I've got.

[Ron Ron Ron]

Stripping off the outer sheath of T&E will be the cheapest way to obtain the necessary cable, but be careful.

If you haven't got the right tool for the job, there's always a risk of either cutting yourself or cutting into the insulation on the inner cable strands.

Been there, got the scars to prove it.

 

Still, it's a cheap or even free option.

 

If you don't want to strip the T&E, the individual inner cables are also available from electrical outlets, but at greater cost. Unfortunately you normally have to buy it by the reel (I think it's usually 100m), but if you can share a purchase with someone, find somewhere that will sell it off the reel, or better still get some off-cuts, that will bring down the cost.

 

Sizes are 1.5, 2.5, 4.0 mmm and larger. The 1.5 and 2.5mm are ideal for a DCC Power Bus.

 

One advantage of the individual cables is that they are available in more than the 2 colours (Brown and Blue) found in T&E. That may be helpful if you want to colour code individual buses/circuits.

 

Colours available are usually:

Black

Blue

Brown

Grey

Red

Green/Yellow

 

.

[RedgateModels]

Stripping off the outer sheath of T&E will be the cheapest way to obtain the necessary cable, but be careful.

If you haven't got the right tool for the job, there's always a risk of either cutting yourself or cutting into the insulation on the inner cable strands.

 

 

Not so much the right tool as the right technique - my Dad was a spark all his working life and this is the procedure:

 

 

Run sharp blade down the end of the cable, keeping the blade close to the bare earth conductor for about two inches. Keep the knife running against the bare earth conductor will prevent the insulated conductors getting nicked.

 

with a stout pair of pliers grasp the bare earth conductor with one hand and take a firm hold of the remaining grey sheath and insulated wires in the other. Pull outwards and down with the pliers and the bare conductor will cut it's way out of the grey covering

 

Keep pulling until you have gone far enough

 

 

 

 

 

[Dagworth]

Not so much the right tool as the right technique - my Dad was a spark all his working life and this is the procedure:

 

 

Run sharp blade down the end of the cable, keeping the blade close to the bare earth conductor for about two inches. Keep the knife running against the bare earth conductor will prevent the insulated conductors getting nicked.

 

with a stout pair of pliers grasp the bare earth conductor with one hand and take a firm hold of the remaining grey sheath and insulated wires in the other. Pull outwards and down with the pliers and the bare conductor will cut it's way out of the grey covering

 

Keep pulling until you have gone far enough

 

You don't even need a knife, use a pair of side cutters at the end of the cable, chop straight into the cable in line with the earth conductor. the two outer wires should part in a Y shape allowing you to grab the earth wire with pliers and pull sideways, splitting the outer sheaf and leaving the two insulated wires untouched.

 

Andi

[RedgateModels]

Side Cutters - you were lucky In my dad's day you had a wooden handled knife that got shorter over the years as you kept it sharpened, a screwdriver (flat bladed, no posidrive in them days) and a pair of "electician's" pliers (which also served as wire strippers)

 

I still follow in his footsteps even though I have loads of the right tools - I generally end up doing most tasks with my Swiss Army Knife ......

[Lady_Ava_Hay]

I generally end up doing most tasks with my Swiss Army Knife ......

 

 

For me it is a Leatherman Wave. Had it at Warley. Most often asked question was 'can I borrow that?'