CAT5 wiring advice please

Hi Guys

I have a client where I am supplying and commissioning he is using his own electrician.
Only a small job, 10 switches, 3 Pro Dimmers and a 4 channel relay unit.

The thing is his electician has wired the 10 cat5 cables back to the distribution board.
These arent all going to connect to the first unit.
So is it OK to wire the 10 cables into a junction box then have 1 cat5 cable going to the first unit.

This wouldnt be done on mains wiring as if each cable comming back was say drawing an amp you would have the single cable at 10 Amps.

Any ideas or suggestions

Thanks
Mark

 

I am no C-Bus expert (definitely not compared to others on this forum), nor am I an electrician or installer. But I do know some things

If you peruse the C-Bus manuals available online, there is nothing wrong with wiring all the C-Bus cat5 back to base. It's just using a lot more cable than necessary, and making a headache for hooking it all up

You could use something like this:
http://www.cbusforums.com/forums/showthread.php?t=3831

But the easiest way IMO would to use a +ve rail and a -ve rail. Twist the blue and orange pairs individually and connect each of them to points on one rail, and twist all the blue/white and orange/pairs and connect to points on the other rail. Then just make one jump lead from the rails to your first output device, and go from there.

(Just re-read you post after coffee. So yes, just what you suggested is fine )

 

It's fine to do this. With so many wires to connect together, I would suggest twisting them together and solder rather than using a connector/terminal strip. We found this to be a much better solution with many cables.

Cheers

 

There were some recent posts on terminating cbus cables. Try this:-
http://www.cbusforums.com/forums/showthread.php?p=19784#post19784

 

Thanks guys, I thought it would be OK wanted to make sure it was good practice before the electrician asks me.
He is already concerned about the nuber of points he is going to have on a 20Amp Pro dimmer

regards
Mark

 

What do you mean by the number of points he is going to have on a 20A Pro dimmer? what exactly is going to be run from it that is concerning him?

 

Huh!? Does the electrician realise that the pro dimmers are 20A per channel??

 

Hi Guys

Yes I know.

Not sure if its the same everywhere but here in Ireland the regulation says you can have a cerain number of lighting points per circuit, I think its 10.

So as some of his circuits are banks of ceiling spot lights, what he is saying is by having 4 channels on one dimmer unit if each has 10 spots he now has 40 points on the main breaker(before the dimmer unit). But the way I see it is it depends on where you classify your circuit. If you do it before the dimmer thaen this could happen more often than not. If you take each channel of the module as a circuit it shouldnt be a problem. Its just convincing him, other electricians havnt had an issue before

Regards
Mark

 

I can't speak for the regulations, but here are some sums;
Assuming low voltage halogens, 50W each, closer to 60-65 watts incl. transformer.

10 lights on a dimmer channel = 650W = ~3A @ 220V
Run 4 channels on one circuit and that's a 12A lighting circuit, which from my limited domestic knowledge is quite a hefty circuit.

 

Froop,
The Pro-Series Dimmers are not all rated at 20A PER CHANNEL, they are rated at 20 Amps for the entire dimmer, so 1 channel dimmer = 20 Amps per channel, 2 channel dimmer = 10 Amps per channel, and 4 channel dimmer = 5 Amps per channel.

It sounds like Mark is planning to use the 4 channel version of the Pro-series Dimmers, so he would be limited to 5 Amps per channel.

If having a breaker rated to deal with around 20 Amps on the supply side is concerning your electrician Mark, then you could look at putting smaller breakers on the 5 Amp load side of each channel. There are alot of people who say this is a waste of time, because if you have a major short circuit, it will still fry the dimmer channel, but at least it would allow you to disconnect each circuit for changing globes, etc.

Just a few things to think about,

Darpa

 

My apologies.. the literature I was reading mentioned that the pro dimmers are rated at "up to 20A per channel". Which is obviously only true with the 1 channel unit.

 

Thanks for the replies guys.
Yes we are using the 4 channel Pro Dimmers, so as per the installation sheet we will have a 20 amp Breaker supply and 6Amp breakers on echa channel

regards
Mark

 

Yes, I would assume that Ireland is wiring to comply with IEC standards, in which case you'd include the Breakers on the outputs as indicated in the installation instructions.