C-Bus limits per switch

We had our house built some 20 years ago, and at the time had C-Bus installed for some of the lighting, phone/networking, and TV.

At the time, halogen downlights were all the rage, and we had these installed in a number of areas, all of which have C-Bus light switches to control them. We also have some lights out the front of our house controlled by C-Bus, also with a sensor.

My question mainly relates to there being limits for each switch. I seem to remember the number 200, looking to see if this was answered in another post, found an old one talking about a maximum of 200W per "channel" (here: https://www.cbusforums.com/threads/what-is-the-maximum-wattage-per-channel.9188/).

So:

- As I said, I recall the number 200 as a limit. The post I linked to refers to a 200W channel limit, so this is likely what I remember.

- We generally have a C-Bus switch controlling a group of up to 4 lights (though 6 in one place). Is each switch likely to be controlling one "channel"?

- The halogen downlights I thought were 50W but may have been 25W (we've had them replaced with LEDs ages ago), and in most places had no more than 4 lights per switch, but in one place have 6 lights on one switch. If we had 50W halogens, that would have been the 200W max for a switch -- though the 6 lights on one switch scenario must have been lower wattage???

- Since we're now using 9W LEDs inside the house, that would mean we're well within the limits per channel?

- I'm not sure what the globes are out the front of our house, but we have 4 lights on one C-Bus switch, so the total wattage must be no more than 200W. These lights are old and looking pretty shabby now, so we're looking at replacing them. At the same time, I'm considering installing an additional light or two. Is this possible to add to the same C-Bus switch if we choose lower wattage globes, so long as the total wattage for the one C-Bus switch remains no more than 200W? Is it that simple?

- We have a motion sensor on these lights out the front of the house. When it's windy, the lights come on automatically, even when there's no motion -- there's nothing at all in front of the sensor that is moving. What could be causing this?

- We also have a motion sensor in the hallway of our house. Similarly, the hallway lights come on when we have the laundry door open and open the front door on a windy day, with a gust of wind going through the hallway. What could be causing this?

Thanks in advance for any help!

 

Firstly, I'm glad to hear your C-Bus system has given you so much great service. The amount of power for each group of lights can vary a bit, depending upon the type of control. What I mean by this is, if the group of lights are on a dimmer, the limit may be 200W whereas if on a relay (purely on/off control), it can be significantly higher. If you had/have a large grouping of lights, then they may be spread across multiple channels of dimming and programmed to operate together from a single switch.

Lights being triggered when it's windy are most likely being triggered by movement of trees. The sensors are passive infra-red (or PIR) and they operate on detection of movement of heat. As the plants/trees are of a different temperature to the surface around them, the sensor will deem this as movement of heat. The system can be programmed so that the sensor is disabled for a period of time if this is annoying (I do this in my own home for the exact reason you have outlined).

It sounds like you don't have an electrician who is versed in C-Bus. I'm based in Adelaide and am happy to either assist you or advise your electrician if they are not comfortable. I certainly don't want to tread on his or her toes. Please feel free to contact me if you feel I can assist you or your electrician. My business is Goodwood Electrical and you can find my contact details on my web site.

Cheers, Chris

 

I guess we didn't get as much out of the system as we'd hoped -- we never did do anything in the way of automation, all the light switches are dimmable which is great, we covered the hallway sensor because the lights always came on at 100% in the middle of the night, and the outside sensor (as mentioned below) always seems to trip in windy weather. We do have distributed TV too, but that's pretty much fallen by the wayside, given the rise of streaming services. And the network cabling was probably the wisest choice -- dual network points in pretty much every room and in the places designed for TVs has simplified networking and TV services.

All the indoor C-Bus light switches are dimmable, so it sounds like 200W limits. I'm not sure about the outside lights, as there probably wasn't a point in being able to dim them. But maybe they're setup the same? Regardless, I believe we're way below 200W as it is with the 4 external lights we have. We're looking to replace these lights, and are considering adding a couple more on the same C-Bus switch. I guess if we choose appropriate lights, or switch to LED globes where possible, we should still be able to stick below a combined 200W use?

No trees in line of sight of the sensor. And it doesn't explain how the hallway sensor is triggered sometimes when we open the front door -- definitely no trees in the hallway! I'd read somewhere that the wind on a cold day can be enough to trigger this type of sensor???

We don't "have" an electrician, the system has been pretty much untouched since we built the house, and we've used a couple of different electricians now and then to do a few small jobs unrelated to C-Bus. So we don't have anyone giving us C-Bus at the moment -- apart from you (thankyou). I saw your web site but didn't see an email option, so will comment here for now. I guess an important question is to check if you service the Grange area?

 

Yes, this is true. There are a number of things you can do to help this. The sensors are supplied with a restrictor plate which can be adjusted to exclude certain areas of detection. This can help a lot. If you don't have this you can just cover up parts of the sensor where you don't need detection. Also the sensor has a sensitivity control and you can also adjust the detection time using toolkit which can help.

Sometimes though nothing helps. I have a sensor in a stair well in the middle of the house that gets tripped when it is extremely windy outside. Doesn't happen very often but it is annoying at night. So I have a switch near the light that disables the sensor until the following morning.