Segregation of safety circuits?

Red16 · Jul 13, 2012

I'm testing a load of new builds and yesterday a little debate opened up between myself and another tester. First off he says segregation of safety circuits applies to the smoke alarms being completely seperate, for example not on the lighting circuit. It has to be on its own breaker entirely. I didn't say he was wrong because I wanted to look in the regs book to confirm first as is my nature but I can't see it anywhere. Is he misinterpreting it?

Secondly I refused to power up an installation and put tested stickers on the board until the main bonding was able to be connected when the incoming pipe work was installed. He quite aggressively told me I was F'ing wrong and that the sticker goes on the board when testing begins??? Now I'm 99.9% sure he's wrong there but before I tell him he is wrong I wanted clarification to be that extra 0.1% certain and tell him he is F'ing wrong.

I'm fairly certain on both these counts but I'm not pigheaded enough to ask for fellow pro's opinions.

Thanks for any clear clarifications

kingeri · Jul 13, 2012

Smokes don't have to be on their own circuit, it is common to put them on the lighting circuit. An advantage of this is that the homeowner will notice straight away if the lighting circuit has tripped!

The main bonding needs to be present during testing, so that answers that I suppose.

AndyL · Jul 13, 2012

Page 123 of electricians guide to building regs states it is actually preferred to have the supply for smoke detectors from a lighting circuit (if we are talking about a standard sized house, large house would be different)

Red16 · Jul 13, 2012

Thanx for the response, that's what I thought on the smokes side, so the main question I have left is what is the exact reason for segregation of safety circuits, what exactly does it refer too?

And I it as 100% confirmation that the tested sticker goes on the board after it is comPleted satisfactorily.

steveberry11 · Jul 13, 2012

Safety circuits are things like fire alarms, and security alarms. Smoke detectors as others state are normally fed from lighting circuits.
How can you complete a test on an incomplete installation? As you state you are doing an EIC if you complete this test you would need to fail the installation ans there is no main bonding. What you can do is the dead tests, record them and return when installation is complete to finish the live tests when happy sticker up. What if there was a cable snagged on a water pipe you may not it with incomplete bonding on a IR test.
If the installation is energised without effective earthing then there are potential hazards.

kingeri · Jul 13, 2012

Segregation of circuits may refer to splitting circuits between more than one RCD, so if one trips, you still have part of the installation on.

Segregation of safety circuits refers to the actual cable runs - i.e. not running fire alarm cables, telephone, data etc. near LV cables.

And yes, put the sticker on when you've finished!

Red16 · Jul 13, 2012

Thank you very much people. I shall now smugly go and correct him. Normally wouldn't be so smug but due to his aggressive curse filled rant yesterday because I disagreed with him I have no choice :

Much appreciate the confirmation guys/gals

1shortcircuit · Jul 13, 2012

"Commonly used Lighting circuit"

Your man is half correct with regards to the smokes being on their own circuit - It can go on it's own RCBO or installed on a "commonly used lighting circuit"

As you know, if the lights go out people will know straight away.

The only time it will be known if the RCBO has tripped is when they go to check the test button at it's next quarterly interval lmao Or when the alarms start chirping because the batteries are running low.