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KNX will be used for home automation of a new home in the UK. It is planned to have KNX switches within the bathroom. The switches will be connected ONLY to the KNX bus, through certified "green" KNX cables of type YCYM. Would there any problems with installing the KNX switches within the bathroom, either outside of zone 2 or within zone 2? Thanks |
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My interpretation of the iee wiring regulations is that there is no restriction covering the use of SELV in any zone in the bathroom, and indeed for light fittings and mirror demisters you will find many 12v products for Zone 1. KNX bus is SELV and thus should be fine for Zone 2. Indeed to put my money where my mouth is, my 2 UK bathrooms have Gira touch sensor2pluses installed in Zone 2. My real concern is whether the relative humidity and condensation issues in the bathroom will cause mechanical failure of the switch: you can get ip44 sealing sets for some basic switches, but unfortunately not for the touchsensor2plus which I have used extensively throughout my property - so I took the risk and have installed the touchsensor2plus and it has been operating successfully for the last 12 months, if it eventually fails then I can move to a simpler but sealed switch. Of course like the rest of any KNX installation in the UK you will have fun explaining to many trades people including experienced electricians that your switches are part of a KNX system and are SELV - since at first sight of a switch in the bathroom they will react badly! |
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I have seen the KNX bus shorting out with a small water leak and it did quite a bit of damage to the device, cable and power supply. My advice would be to use a binary input module to the KNX with a flush s/steel button mounted on a s/steel plate and seal around it with sealer. this will allow you to toggle the lights on and off and if done right looks very professional and cost effective. here is an example of a button, or you could look for a membrane type multi-button switch http://cgi.ebay.co.uk/Stainless-Red-Light-OFF-ON-36V-Waterproof-Switch-R4M-/270459355769?pt=LH_DefaultDomain_0&hash=item3ef8a24279#ht_2688wt_1216 if you use the theben ta4 or abb 2.2 push-button interface it can also control a LED if required. We have done this for kitchen areas etc. never with a problem. Interesting info. Can you share with which KNX button you had the water leak? I am surprised about your secondary damage to cables and power supply. AFAIK the certified cables are rated at 2.5A (please correct me if this is wrong). I am not aware of a standard KNX power supply rated higher than 640mA. I wonder what type of damage to cable did you experience? If certified KNX devices are so sensitive it is time that the manufactures get their act together, in particular in light of their prices. Of course not every one who is selling "KNX" equipment is a member of the KNX organization...
(Jun 15 '11 at 12:34)
KNXHOME
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@mgx Thanks for your answer. Concerning the relative humidity and condensation issues I hope that Gira has designed them with use in bathrooms in mind, even if they are not ip44 rated. I am sure elsewhere in the world they are being used more frequently in such an environment. BTW, I am planning to use a touchsensor3komfort model, as the touchsensor2 series has been discontinued. Indeed, I am expecting some blank faces from the trade about the KNX installation. Do you have a name of a suitable electrician? My project is in London. Can one send a PM via ask.aboutknx.com? |
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You can't make assumptions: it comes down to the specifications. The Touch Sensor 2+ is rated to 95% Relative Humidity non-condensing, and is only IP20 rated. There's a real risk of exceeding those ratings in a bathroom with steamy showers and wet hands, in which case the performance is not guaranteed. I expect the ratings of the Touch Sensor 3 are similar. I don't have a reference for an installer unfortunately. Originally when I looked for a reference, I contacted Ivory Egg (knxshop.co.uk) who provided a reference. |