Thanks Marty, I think I will be doing the same.  Cheers, Ian.

You are most welcome Ian. I didn't have a clue about these things until I found this wonderful forum   

Marty

I know that feeling very well Marty, I defenitely feel like a

Did you use the 1.5mm twin & earth or the 2.5mm?

Quote from: justintime on January 01, 2013, 09:25:17 PM
Thanks Chaps.

I was thinking of getting some cheap twin & earth which is Max. Rating: 240V, 16.5A.  Will that do or is it over kill/underkill?  Cheers, Ian.

Total overkill but its cheap and works well so being overkill isn't a problem!

What would be the ideal capacity EtchedPixels?

DCC is 12-22v or so at whatever your system can output max - so usually 5A or less.

So you want anything thats rated for the voltage (plus a bit - say 24v) and sufficient power. Low resistance is good.
I use cheap speaker wire but there is nothing wrong with using cable over the rating if it is cheaper (and it often is because of the volume produced)

Quote from: EtchedPixels on January 02, 2013, 11:29:17 AM
DCC is 12-22v or so at whatever your system can output max - so usually 5A or less.

Sorry I have to disagree with that. 

The current rating of a cable is based on how much it can carry without getting too hot.  However with DCC voltage drop is a much more important issue, since if there is too much voltage drop a short circuit won't cut the power but will just stay there heating up. 

If you have a 5 amp system then the power being dissipated near your short could be as much as 75 watts - think of how hot an old-fashioned lightbulb gets and what that amount of heat could do to your stock or track.  Due to wiring errors on my part I melted a Dapol Voyager that way, fortunately not too much of a loss as it was a rotten runner anyway! 

Normally the DCC bus needs to be made of cable with a much higher current rating than your DCC system maximum current - possible exceptions are for very small layouts or if circuit breakers are fitted to reduce the maximum current.  And it is essential to check that a short circuit anywhere on the layout cuts the power immediately, usually done by putting a coin across the rails.  Droppers can be much thinner provided they are kept short. 

Cable voltage rating isn't significant for DCC systems (well it might be if you found some cable rated at less than 20 volts...). 

The mains cable rated at 15 amps should be OK for most layouts, but lighting cable at 5 amps probably isn't.  Bear in mind also that twin+earth is single core wire so should only be used in places where it won't be moved around after installation, otherwise the core can break.  Flying leads for portable layouts need to be made with multi-strand cable. 

Quote from: justintime on January 02, 2013, 11:06:31 AM
I know that feeling very well Marty, I defenitely feel like a

Did you use the 1.5mm twin & earth or the 2.5mm?

I used the 2.5 and as I say, it works a treat  . Good luck with it Ian 

Marty

Quote from: edwin_m on January 02, 2013, 01:29:15 PM
The current rating of a cable is based on how much it can carry without getting too hot.  However with DCC voltage drop is a much more important issue, since if there is too much voltage drop a short circuit won't cut the power but will just stay there heating up. 

The current rating is based upon how much heat it can take at its top rated voltage (RMS for AC). 240v at 5A is a lot more than 75W.

Voltage drop matters but its not so much the wiring as the risk of damage to bits of the loco which have fine wires and are easily damaged. Thats why the coin test is useful (check a coin across the rails at the various distant points trips the short circuit protection)

Alan

Thank you.  I have just purchased 7.5mtrs of 4 core 1.5mm which has a maximum rating of 240 volts = 16.5 Amps.  Thats 3 lots of 7.5Mtr wires for under a tenner. They should do the job for the "ring main" shouldn't they?
I have also picked up some 16/.02 black and red for my feeds to points track etc.  Hope I have done the right thing?   Cheers, Ian.

Quote from: EtchedPixels on January 02, 2013, 04:31:30 PM
The current rating is based upon how much heat it can take at its top rated voltage (RMS for AC). 240v at 5A is a lot more than 75W.

See here for a description of current rating.  It doesn't depend on rated voltage. 

http://en.wikipedia.org/wiki/Ampacity