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Topic Title: zucchini lighting busbar
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Created On: 11 February 2015 11:07 PM
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 11 February 2015 11:07 PM
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Joined: 10 December 2014

Ok folks I have 3phase & N lighting busbar to install in a new factory and have been asked to supply each phase via a single pole mcb so that should a phase drop out (trips) I will still have 2/3 of the lights still operating! I would be in the opinion that a triple pole mcb would be required so if a fault occurs the entire circuit would drop out and the emergency lighting would come on

Anyone any thoughts on this?
Would 3 single pole mcb be acceptable if all labelled & identified correctly?
 11 February 2015 11:19 PM
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Yes, it's how i'd do it.

The toss up is between is it more dangerous for the entire light track to fail plunging the place in darkness and having an unskilled person working on the installation not knowing to isolate all three phases. You wouldn't really get a novice working in places like that unsupervised and so if everythings labelled they should be fine.

 11 February 2015 11:47 PM
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To be honest, the effect would be similar to using fuses, where you would most likely only have a single fuse operate.


 12 February 2015 07:34 AM
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Does zucchini busbar trunking have front end fuses on the live end?

I've not done any for several years, I can't remember weather there were front end fuses or not. The tap offs are usually fused if it's any help? The idea usually is to get discrimination through the tap off fuses, and the MCB feeding the busbar shouldn't ever open unless there is a fault with the busbar or the cable supplying it. If the MCB is tripping on overload then there is a design issue.

Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 13 February 2015 01:25 PM
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Since pole MCBs are fine, but you will need "at least one device" that simultaneously disconnects all the line conductors (reg 559.6.2.3) - as I read it, that needn't be and ADS device - a simple isolator (switch disconnector) would do.
- Andy.

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