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Sintra

Sintra

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Came across a very strange circuit set up today and was wondering if anybody had seen anything like it before. I will state now that this is not a UK installation so BS 7671 might not be applicable. OK we have six lighting circuits with 4 fittings per circuit each controlled by a 1 gang 1 way switch (very simple so far). Each circuit is fed via a 15A 3871 MCB but is fed from 2 seperate DB's. For example lighting circuit No. 1 is fed from DB 1 circuit 1L1 and also DB 2 circuit 1L1 and lighting circuit 2 is fed from DB 1 circuit 1L2 and DB 2 circuit 1L2. The neutral for the circuit only comes from DB 1. The circuits are all wired in pvc insulated cable within galvanised conduit and trunking. I have attached a schematic drawing for 1 circuit to try and give a clearer picture of the set up. I hope someone can explain this as it took me about 4 hours today to isolate the damned things as the 2 DB's are not even close to each other and i hadn't got a clue that they were fed from different sources. :mad2:
 

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The only time I have seen anything like that is in TSB Banks probably 20 years ago where some special circuits are fed by essential and non essential supplies, but the switching arrangement was catered for this, when one supply was killed the other then took over but control gear was in place to stop back feeding, I didn't get too involved with it as I was helping another spark on the job at the time not running the job, that set up you have shown Sintra is dangerous by the look of it and needs disconnecting from one board, it looks strange for sure, is there anything else connected before the switch on one of the feeds?
 
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No mate straight from the 2 MCB's to the switch. Guys have been tracing out all the lighting circuits on one floor this weekend and they are all fed from 2 MCB's will pop up a wee drawing in a few minutes.
 
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That looks to be intentional.
A fail safe back up for the wiring installation, with no switching between the 2 required.

It must be a Hospital or High security building, Prison maybe??

If it's not the U.K it must be permitted and must be familiar to persons who normally work on that type of system
 
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This setup is used on railway in places for essential equipment. Delve into it further before disconnecting, if its only lights tho I can't see why it would need to be! Is this building domestic or commercial?
 
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Yes very confusing, I still think it may be an essential / non essential system somehow, (looks that way to me) and due to the generator, seems like it may have something to do with that, but the schematic doesn't make sence and seems almost dangerous, sorry fella, I don't think I can help with this one and it mut be something we UK sparks don't get involved with, hence the confusion, maybe tony or E54 may have an idea when they see the drawing Fella.

Mike
 
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MDJ said:
Yes very confusing, I still think it may be an essential / non essential system somehow, (looks that way to me) and due to the generator, seems like it may have something to do with that, but the schematic doesn't make sence and seems almost dangerous, sorry fella, I don't think I can help with this one and it mut be something we UK sparks don't get involved with, hence the confusion, maybe tony or E54 may have an idea when they see the drawing Fella.

Mike
Click to expand...

Cheers mate seems a bit dangerous to me also that's why I'm going to get to the bottom of it.
 
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Seen it and installed it where two or more substations would be linked for ancillary power and lighting. Mind you I did fit change over switches on the inter-linking feeds. As we pulled the 11KV cables in a couple of 433V cables would go in at the same time.
 
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