Comparatitive cost of standard and C-Bus cabling

Be interested in what the comparative cost of cabling a house normally ie. no C-Bus installed versus cabling pretty much all C-Bus.

I suppose what I am trying to get a handle on is just the cost of wiring and the cable costs. This would not include the C-Bus equipment obviuosly the C-Bus equipment will alway make the total installed cost more expensive than conventional give the same house size and layout. I suppose the question is what would be the first fix or rough in difference would be?

Would it cost more or less for the same size house to supply and install C-Bus or conventional electrical wiring. Assume that in the C-Bus senario that the C-Bus equipment is located in the centre of the house.

If one was to get an electrician to then fit off to the C-Bus equipment confirm on off operation at the C-bus equipment do you think this would be more or less work than a conventional second fix?

Cheers,

Fleetz

 

I personally think that C-Bus would be more expensive, firstly because the average "wire-jerker" (lowest cost) electricians should definitely NOT be used for anything to do with home integration !

The "common procedure" of putting all the C-Bus equipment in one central location also adds HUGELY to the cost of cabling. Consider that every single "load point" has to have a 3-core cable run back to that central (C-bus) location. This aspect alone would (at my guess) at least TRIPLE the amount of mains cable used for the lighting.

Further, doing the wiring that way decreases the flexibility considerably - in effect you are hard-wiring the lighting system and putting all the switches and dimmers in one place, then putting in another system (a C-Bus network) from all over the house to tell that hard-wired system what to do. This is very inefficient !

To minimise cost and maximise flexibility, distribute the C-Bus output units into nodes in cupboards, etc throughout the house. Have short runs from those "nodes" to the local loads. That way, your cable costs are much lower, and you have the possibility of splitting up the circuits much more, even if (initially) they are commoned into a single relay or dimmer channel.

If all your switching and dimming is completely distributed (ie: C-Bus Output devices all AT the load) then the cost of C-Bus would be lower than a conventional system. For example, in an office where you wanted individual control of every single light fitting, you'd put the control into each light (eg: using DALI ballasts) because you'd be crazy to wire 1000's of individual lights back to a central location (even though that is how many integrators do it). But the more that you group the C-Bus Output devices together (inside switchboards), the higher the price due to the extra cabling required.

As an example of an absolute worst case (that I was given the unpleasant task of commissioning, after someone else designed it) was a 3 story house with over 150 lighting loads, with all C-Bus devices mounted in one place under a staircase (middle floor). The house was full brick / block construction and the bunch of cables coming into that place was about 250mm diameter, and every one went out to it's respective room / area via cable trays and ducts and conduits.

When I had finished getting everything running the client asked me to individually switch 2 upstairs rear exterior lights, which were 1 floor up and 1/2 way across the house from where the C-Bus outputs were.... guess what, they'd been commoned together and only one cable brought back down to the relays, so there was absolutely no flexibility ! The client was very angry because they were under the immpression that C-Bus was gunna handle all that kind of stuff - but nobody considered that they might want to split that particular circuit so the cabling wasn't put in for that.

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So, the lesson is... TPS cable is CHEAP and at design stage it's almost impossible to determine exactly how you are going to USE the house and the areas within it. Therefore wire it up in such a way that you can change things easily as required. Don't put 8 lights in your loungeroom on one circuit, wire then individually or at least in pairs. In areas where you haven't got any acess, put heaps of spare (empty) conduits in that you can pull extra cables through later.

To take FULL advantage of the flexibility of switching that C-Bus allows you far into the future, you REALLY need to plan your cabling carefully. You have to add heaps extra so that you will have a cable there in future for whatever you might need... and that definitely costs more, but in the overall scheme of things it's not really that much to pay.

I guess that didn't really answer the question very concisely, but hope it gave food for thought

John

 

Thanks John,

Appreciate the input and IS most helpful and food for thought indeed. The nodes idea I could see considerably reducing the cabling cost on larger installations.

There doesn't appear to be any reference cabling book or data that Clipsal put out on how to approach a cable plan. I suspect it is only experienced people like yourself that through real experiences work out the best cabling solution for each job.

Thanks again,

Fleetz

 

Biggest saving will be all the RWB cable between multiple switches, and the intermediate mechs, a plate of 4 of those and your most of the way to a c2000 series 4 button c-bus. In a big open plan environment this can add heaps of cables that c-bus eliminates.

 

Agreed, I completely forgot to comment on the fact that as soon as you start putting multiple switches on plates, and then having 2-way and 3-way switching... then C-Bus will become much more competitively priced. If you can get the output units close to the loads, then it is very possible that the reduction in switch wires might just make C-Bus cheaper than conventional wiring

But please don't try an save money by putting 6 or 8 gang switches unless you really really have to. It's an absolute PITA to work out which switch does what, even if you use DLTs. Spread the swicth locations around - put them close to where you sit and/or use them. At the very least, there should be one at every door opening, preferably one on each SIDE of each door opening.

Also keep in mind that TPS cable is dirt cheap. 1.5mm Twin or Twin+Earth can be bought for about $60c a roll wholesale. So, even if you put 1000 metres of cable in to wire up your house, the total value is under AU$1000, which is not much compared to the price of the C-Bus output devices you'll be connecting it to

 

Not in NZ its not, and the cableing cartell put a stop to bunnings and mitre10 selling the click branded pirelli stuff from aussie by hyping up a scare to do with chinese imported cables.

We pay close to $2 a m for the RWB stuff over this side of the ditch, and 2c+e is still over $1/m unless you get the guy at ideal on a good day.

edit - oops typo