C-Bus dimmer in ceiling space

Hi There,

I have a sparky coming to retrofit cbus into my house next week.

He has suggested placing the dimmer and relay units into a new board in the ceiling cavity to save having to increase the board size and to simplify the job - has anyone done this before? I’m conscious that Melbourne gets quite warm in summer so keen to get some opinions before progressing with this.

 

Hey KS,

It generally isn't recommended, as you have said roof spaces can get quite warm and if you are installing dimmers they can generate quite a bit of heat themselves. Schneider generally wont warranty the gear if they know they have been installed into a roof space. The units are rated for 0 - 45c and middle of summer spaces can get quite a lot above this! Especially this year!

Installation manual here:
http://shop.mysmart.com.au/assets/brochures/L5504D2UP.pdf

Page 11 for temp and humidity

 

Hi KS
Don't allow this to happen, as mentioned above SE won't cover failure due to incorrect installation, the units are guaranteed for 2 years, your sparky may cover replacement during that time. the reality is that they may last in that poor situation longer than 2 years then fail.
Electronic components can get stressed due to heat but continue to function, though eventually they fail.
Also ensure that the units are mounted the correct way (horizontally) to allow air to flow through the units.
Colin

 

This is actually an interesting discussion. I've seen plenty installed in roofspaces and actually have a couple in mine. I've only ever seen one failed unit and it was one that had previously been installed in a harsh environment (not a roofspace the techs at Clipsal told me). Whilst it is not recommended, it is a lot more common than you may think.

 

Ive just dismantled a dimmer unit with a PSU onboard. The caps were marked 85C so definitely a no.

Starting with an ambient of 45+ then trying to sink heat from the triacs it would cook the caps in no time.

 

I have a 4 Ch 'C-Bus 1' black box still going strong in my roof space! The rest of mine is in the garage though.

 

I too have many old D750's (black boxes) in the roofspace. They've been in there for 20+ years and have never failed and it gets over 55 degrees in the roofspace often (have some C-Bus temperature sensors in there that log to the touchscreen), but haven't seen it ever go above 62 degrees. Iron roof with no real ventilation. There's been lots of speculation of in-roof temperatures over the years but I haven't heard of anyone else who actually measures and records the temperature other than me.

 

I seem to recall that these units were constructed to withstand the higher temps in a roof space. I dont know if something has changed over time but I am sure in the early days that it was suitable for roof space install. Its not the location I would choose though.

Put a secondary board in the Garage - they still tend to be warm spaces but not as bad a the roof.

 

Hi
Its not the best place for them however I have all my CBus gear mounted in roof space, every model from 1994 white enclosures, Black Box and din rail types all working well the only failures i have had is some older switches have failed.

 

Thanks for the responses and discussion. I’m guessing despite being DIN mounted as long as the breakers are at the primary board there’s no access requirements that apply to this gear?

I’m going to suggest a secondary board in the wardrobe as an alternate option to my sparky and see if that can fly.

 

You need to be aware that dimmers will hum consider the noise too.