Official recommended Fusing & MCB for CBus modules

[robj]

I am spec'ing the CBus modules for my new house and want to protect them from surges and short circuits. The has been some debate/recommendations on the UKHA mailing list but I'd like the official line if there is one. So I guess my question is :

What is the CBus official recommendations for short protection of the modules ?

Are they secified

Thanks

Robert

[MrEcosse]

Basically the units MUST be protected, they have no internal protection against overload and failure to do so is a safety risk. Clipsal make 1A and 2A breakers that are suitable for the protection TSC101 and TSC102 are the part numbers.

[UK Household Automation]

I think i'm correct in saying - Seperately fuse each circuit - the couplers themselfs are NOT overload protected!

[Jannie]

I agree on this one.

We need an OFFICIAL statement on correctly wiring the dimmer units. I've had one CIS person tell me I MUST use fuses on the dimmers while another CIS person from the same office told me (after I installed a large number of fuses) that it's not needed at all. Yet another person told me to use a 3A breaker per dimmed circuit....

I've lost dimmer units even though they were fused with a 1A or 2A fuse as applicable.

What is the CIS party line on this?

Jannie

[UK Household Automation]

We recently had a case where the 2A MCB (type B) kept tripping there was a transformer as part of the load and although the running currrent was well within the inrush was too great even with a long ramp time we fitted a 2A MCB type C.

[Ross]

I believe the official line runs along the scenario that individual circuit protection of each output leg is not a requirement of the installation process. It may be a requirement of a certain countries Installation Wiring rules and therefore mandatory.

Each country has its own wiring rules and therefore they will take precedence overall as a matter of “sticking to the wiring rules”. In Australia the SAA 3000 does not make it a requirement.

As for the CIS line however there has never been a cold hard requirement for additional protection. The choice an installer has, is his alone should he deem it necessary to have additional protection. Personally I don’t believe it’s worth the cost or the hassle to install additional protection to try and save a triac from toasting itself in the event of a dead short.

Redundancy, my second favourite word.

Cheers

[znelbok]

Personally I don’t believe it’s worth the cost or the hassle to install additional protection to try and save a triac from toasting itself in the event of a dead short.
Cheers

Try telling a customer that has all eight channels used on a dimmer that because one channel has blown that it is going to cost them $1000 to fix it.

Yeah leave one or two channels free for such an event, but you shouldn't have too. Also what happens when those spare channels have been used from previous failures.

Redundancy, from where I come from means having a second in action along side the primary, (while not possible here), it is also not ecconimically viable for a homeowner to utilize redundancy as well.

Mick

[Colin Smith]

Greetings
If I recall my electronics theory correctly, then even if the circuit is protected there will still be a race "Fuse V Triac". If the fuse were to win the Triac may not be in good shape anyway. Repair of the units is something I have not had to deal with but I can see there could be issues. A question I have not asked is do they repair / and refurbish units that have faulted?

As an aside. I have also trained on the Lutron products and was told that they (Lutron) do not warranty their product if the light they are controlling is "sat vertically" (Candelabra style), as opposed to hanging vertically. I was advised to inform any customer if performing this type of installation of the lack of warranty. The reason is the filament can fail and fall to the base of the bulb and short out phase / neutral taking out the triac. (This could just be the local distributors stance)

Colin Smith

[Frank Mc Alinden]

Hi Colin

>A question I have not asked is do they repair / and refurbish units that have >faulted?

I had a channel go down on one of my dimmer modules and sent it off to clipsal Adelaide for repair and was returned within 2 weeks which i thought was pretty good service...........

Frank