Weird flickering fault

Hope someone can help.

We've gone to a new client with an existing installation to help a fault with an intermittent flickering circuit and also flashing keypad buttons (Saturns)

Did a site audit first and found that everything appeared normal; voltages on the bus ok (between 28.5v and 30.4v), all devices scanned ok etc.

Did find however that the cbus cable was not installed very well at the back of the keypads i.e cables unwound but not twisted up again. Maybe that's nothing but not how we would install.

Also no programming file.

So we can gone in to first sort out the cabling and re-assemble the programming file.

In this particular room with the flashing lights when taking out the postitive leg of the bus wire the lights went on/off momentarily. When trimming the and cutting that wire the same happened. It's like you've de-energised the actual load for moment. Very strange and no other instance of this anywhere else on the network while correctly the cable.

Any ideas much appreciated.

 

Could it be an intermittent short at 1 of the switches or cable runs (possibly antagonised by water)?

 

Or is that the first switch on the system from the output units and when you cut the cable you activated the all off override
Hence all 4 pairs come to that point
Colin

 

Thanks for your replies. These 2 keypads are on 1st floor the middle of the install and both reacted the same way and it definitely when the positive was cut. There was no contact with the negative leg.

The other aspect that client explained yesterday (new info) was that the flashing lights affect bathroom ceiling circuit also at the same time. I've checked and the two circuits are on the same dimmer. When they do flicker, the keypads all flicker as well.

Could it be the dimmer? The other circuits on this dimmer aren't used.

 

I would go along with Colin here and check out the remote on/off pairs (the green and brown). Have they continued them through at the switch or are they just cut off and floating? If the switch wiring is poor as you say the remote on/off pairs could be making intermittent contact with themselves or the cbus pairs. This is the most likely cause for all channels of an output unit to change intermittently.

 

Thanks guys, i think that this is a strong possibility and am going to re-terminate the cables to the brick anyway. Pretty sure that all 4 pairs are wired in from the keypads.
Thanks very much and will report back.

 

And the answer was...the neutral on the power side of the dimmer brick was not screwed down. Having re-terminated all signal connections and testing all voltages got to this point and there is was.
Thanks again for all your help guys.

 

Good to hear you have found the problem.