Copper Tape for DCC Power Bus

[Magna-N]

I am setting up my first DCC layout and saw that adhesive copper tape/strip can be used for providing a power bus.

 

Is this correct?

 

If so, where can I obtain such tape/strip?

 

Regards

[Andy Y]

I've just had a roll arrive via ebay which was sufficient for my needs but thicker/wider versions are available elsewhere if needed - http://cgi.ebay.co.u...e=STRK:MEWNX:IT - delivery took 2 days.

[shortliner]

I got some a while back from a firm in Bournemouth who deal in leaded glass crafts - very pleasant and most helpful to deal with. The tape is called "Masterfoil Plus" and cost £3.95 for 36 yards. That was some time ago, and it was used for my shoebox layout - I'm sorry but I can't remember the name of the company.

 

Edit - looking on Google, I'm fairly sure that this is the firm

http://www.cylex-uk.co.uk/company/bournemouth-stained-glass-14243696.html

[cromptonnut]

I've used it too, picked a roll up from the ZTC stand at an exhibition a few years but I'm not sure if they still do it.

 

DCC Supplies list two types at http://www.dccsupplies.com/shop/advanced_search_result.php?keywords=tape at 18mm and 24mm width x 33 metres. As usual, no connection except satisfied previous customer etc etc.

[Davidjsmith]

I bought some more tape from ZTC a short while ago cannot remember how much it cost though !The other links may be cheaper?

[Ron Ron Ron]

DCC Supplies and ZTC were charging a much higher price than elsewhere (two or three times as much IIRC ?).

 

There are various suppliers, including Doll's House kit retailers, selling it cheaper.

 

This Copper tape comes in different sizes, so ensure the one you choose has enough capacity suitable for a DCC Power Bus.

 

Having used it in a few applications, personally I wouldn't use it for DCC.

[GasDad]

Having used it in a few applications, personally I wouldn't use it for DCC.

 

Any particular reason why ? Just curious really

 

James

[Oldddudders]

Any particular reason why ? Just curious really

Obviously I don't speak for Ron, but DCC power busses are recommended to have a high current-carrying capacity, so the full power reaches the further extremes of the layout when needed. Thus a wire with an adequate cross-section is recommended. Copper tape is essentially very difficult to compare to "round" wire in effective cross-section. It will convey the voltage, maybe not the full current, which is the point of the exercise. If copper tape really appeals, use the widest gauge available, on the grounds that it will have the best chance of delivering worthwhile current.

 

Copper tape first came to my notice in the '60s, as the standard current-collection medium for slot-car racing tracks built by clubs and commercial concerns. Hardboard, jigsaw to cut the groove, copper tape either side. Oh, yes, and Snowcem or similar to give the hardboard some "tooth" for your Jim Clark Lotus Cortina's tyres!

[Crosland]

Obviously I don't speak for Ron, but DCC power busses are recommended to have a high current-carrying capacity, so the full power reaches the further extremes of the layout when needed. Thus a wire with an adequate cross-section is recommended. Copper tape is essentially very difficult to compare to "round" wire in effective cross-section. It will convey the voltage, maybe not the full current, which is the point of the

 

It's easy if you know the thickness or the weight, but none of the DCC biased suppliers seem to want to tell us. This stuff: http://www.kemtron.co.uk/buytapes.html is .035mm which is 1oz copper (one square foot weighs 1 ounce), as found on a lot of printed circuit boards. This stuff will be made in such vast quantities that I suspect most tapes are the same.

 

It is known that 1oz copper has a resistance of 0.5milliohm per square. That's per square anything, take a square of any size and it will have an edge-to-opposite-edge resistance of 0.5milliohm (the resistance increases with length but decreases equally with width).

 

So, a 25mm wide tape will have a resistance of 0.5milliohm per 25mm length, or 20milliohm per metre. A 10 metre bus will be 200milliohm and will drop 1V along it's length and dissipate 5W at a current of 5A (2V and 10W when you include both the feed and return conductors). Narrower or thinner tape will be proportionally worse.

 

I leave it to individuals to determine if it is suitable for their application, given specific lengths, track voltage and normal loading, but I have to smile at the DCC supplies website current measurements that make no mention of the length of tape or voltages used. Their advice that 5mm tape is ideal for the power bus should be treated with suspicion until you know the thickness of the copper (don't just measure the tape with it's adhesive and backing!!!). If it is 1oz copper then the 5mm tape would be 1 ohm/10metres and drop 5V (10V) at 5A, definitely not suitable for a power bus.

 

Another way of viewing this is that even a modest run of 5mm tape could have a high enough resistance to prevent a boosters current limit from operating correctly.

 

Andrew Crosland

[Ron Ron Ron]

Any particular reason why ? Just curious really

 

James

Hi James

Andrew has covered it most comprehensively.

I haven't the technical knowledge that Andrew has, but I've read enough in the past to form some doubt about the suitability of this stuff for a DCC Power Bus.

I have used it for low current applications (Dolls House wiring), but not on a layout.

[Crosland]

I have used it for low current applications (Dolls House wiring), but

It's very good for buildings on the layout and carriage lighting. You can solder surface mount LEDs between parallel strips of thin tape. If you alternate the polarity of each LED then remove small sections of tape you can make a long string to run them in series from a higher voltage. But do it on a false roof from thin plasticard rather than risk melting the real carriage roof with the soldering iron!

 

Andrew Crosland

[Anthony]

For those of us who have already gone down the copper tape route (run of perhaps 18'), would a suitable fix in order to overcome any potential problems be to add further feeds from the power source at, say, 6' (or longer?) intervals? It may seem a bit simplistic, but the alternative of scrapping droppers from perhaps 80 or 90 yards of track and 30+ points just doesn't bear thinking about!

 

Anthony

[craigwelsh]

For those of us who have already gone down the copper tape route (run of perhaps 18'), would a suitable fix in order to overcome any potential problems be to add further feeds from the power source at, say, 6' (or longer?) intervals? It may seem a bit simplistic, but the alternative of scrapping droppers from perhaps 80 or 90 yards of track and 30+ points just doesn't bear thinking about!

 

Anthony

Might be worth testing via the 'penny test' all points on the bit wired to check the booster always cuts out quickly and correctly.

[Edwin_m]

Certainly further feeds using a suitably fat cable will help with this.

[Crosland]

For those of us who have already gone down the copper tape route (run of perhaps 18'), would a suitable fix in order to overcome any potential problems be to add further feeds from the power source at, say, 6' (or longer?) intervals? It may seem a bit simplistic, but the alternative of scrapping droppers from perhaps 80 or 90 yards of track and 30+ points just doesn't bear thinking about!

 

Anthony

If it ain't broken, don't fix it, but do check that the booster's overload protection works as expected.

 

Andrew Crosland

[GasDad]

Hi James

Andrew has covered it most comprehensively.

I haven't the technical knowledge that Andrew has, but I've read enough in the past to form some doubt about the suitability of this stuff for a DCC Power Bus.

I have used it for low current applications (Dolls House wiring), but not on a layout.

 

This has turned into a very informative thread - thanks, particularly to Andrew for the detailed answer.

[Magna-N]

Many thanks for all of your helpful information and tips.

 

Sorry I have not thanked you sooner, but my PC suffered "Brain Death" and it I have only recently got it going again.

 

I have decided not to use tape, but stranded wire for the main bus and single core droppers to the rails.

[trisonic]

So what weight of wire should be used (or recommended) for the power bus? By the way do so-called suitcase connectors work with all kinds of wire?

 

Best, Pete.

[Crosland]

So what weight of wire should be used (or recommended) for the power bus? By the way do so-called suitcase connectors work with all kinds of wire?

 

Best, Pete.

 

As thick as possible for the bus.

 

For reliability, it's very important that you match the wire guage to the suitcase connector. They come in different colours for different wire guages.

 

Example from Rapid http://www.rapidonline.com/Cables-Connectors/Connectors-Single-Pole/Splices/Tap-blade-and-fuse-splices/63979

 

Red for 22-18 AWG and blue for 16-14 AWG

 

Or http://www.rapidonline.com/Cables-Connectors/Connectors-Single-Pole/Splices/Snap-on-and-mid-way-wire-connectors/72345

 

Red: 22-18 Blue: 18-14 Yellow: 12-10

 

Andrew Crosland

[Magna-N]

I recently read an article in the June 2010 edition of British Railway Modelling by Nigel Burkin (pages 50 - 55).

 

This article gave some very helpful hints & tips; especially for a "Muppet" like me.

 

Regards

[trisonic]

Thanks, Andrew! Now to ensure that info is directly translatable between the UK and USA.....

 

 

Best, Pete.

[DaveyH]

When I started with the DCC wiring on my layout I found this site very helpful, particularly as it refers to current Maplin goods for those of us in the UK.

 

http://www.dccconcepts.com/index_files/DCClayoutwiringwire.htm

[sse]

Hi all

 

Quick question on the tape - is the glue conductive - i.e. if it breaks can I overlap another layer to maintain conductivity?

 

Thanks

[amdaley]

Hi all

 

Quick question on the tape - is the glue conductive - i.e. if it breaks can I overlap another layer to maintain conductivity?

 

Thanks

 

I wouldn't think so. You could link different pieces of copper tape with lengths of wire soldered to the tape.

[richard brown]

hi sse the glue is conductive I have use it a lot with no problems just push it down hard

 

Richard