BS7671 Explained

[SgtTrojan]

The domain has expired! :O :O :O

www.bs7671explained.com

I don't know if any of you have visited it before but it made an excellent reference point for fast answers. The guy who put this together needs a knighthood but the place where it is hosted wants its renewal money.

Does anyone know who made it?

 

[ban-all-sheds]

http://web.archive.org/web/20080719075855/http://bs7671explained.com/index.html

 

[SgtTrojan]

You beauty!

Thanks Sheds

 

[holmslaw]

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[ban-all-sheds]

• To avoid eddy currents, conductors of an ac circuit should not be installed in separate steel conduits. 521.5.2
  
• The conductors of a 230v circuit installed within a ferromagnetic enclosure must be arranged so that the phase conductor, neutral conductor and the appropriate cpc of each circuit are contained in the same enclosure. 521.5.2
  
• Single core armoured cables must not be used in an a.c. circuit. 521.5.2

Which of those is almost complete bollerx, or if 2 out of 3 are fine which one is 100% bollerx?

It would be of benefit to the entire forum if you could explain.

 

[holmslaw]

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[electronicsuk]

3 is complete bollerx, having installed numerous a.c. single core armoured cables over the years.

Yes "complete bollerx" was an exageration, its only 33% complete bollerx.

So 521.5.2 in BS7671 is wrong? The only way to use single core armoured in an AC circuit would be not to earth the armouring, which of course is not an option.

Plenty of people on this forum feed their class I light fittings from an unearthed circuit. I guess that must make it OK too.

EDIT: Before someone picks up on it, I probably should not have said that there is only one way to use single core armoured in an AC circuit. However, other methods such as only earthing the armour at only one end will require careful design consideration, and would be best avoided if at all possible.

 

[plugwash]

To avoid eddy currents, conductors of an ac circuit should not be installed in separate steel conduits. 521.5.2

True though it could be more clear about what it means by seperate conductors.

The conductors of a 230v circuit installed within a ferromagnetic enclosure must be arranged so that the phase conductor, neutral conductor and the appropriate cpc of each circuit are contained in the same enclosure. 521.5.2

BS, for example a lightswitch generally has only lives yet is just fine. What is actually important is that for each hole in a ferromagnetic enclosure the currents in and out are balanced.

Single core armoured cables must not be used in an a.c. circuit. 521.5.2

semi-true, single core armoured cables with ferromagnetic armour should not generally be used for AC because of eddy currents. Which is why they make single core AWA cable.

 

[holmslaw]

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[electronicsuk]

521.5.2 is absolutely correct, you're just demonstrating you lack of electrical installation knowledge, keep digging.

I actually made an edit to my post while you made your response, but for the most part stand by what I said. Single core SWA is best avoided in AC circuits, it just isn't practical. If you want to point out how use of such cable can safely be implemented, please do feel free to do so. I'd much rather learn something than be on the receiving end of your one-upmanship and snide comments.

 

[holmslaw]

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[ban-all-sheds]

When are you going to stop acting like a ****?

 

[Grizzly]

If you want to point out how use of such cable can safely be implemented, please do feel free to do so. I'd much rather learn something than be on the receiving end of your one-upmanship and snide comments.

Way out of your depth. when are you going to stop digging.

Put your money where your mouth is, holmslaw, or stop wasting everybody's time. It just gets very boring.

 

[1john]

Well as he has said, it is something which he has done, therefore it cannot be wrong. I suspect there will be a reg mentioned about every installation requiring one point of isolation for the whole installation next..... yawn....

 

[NotHimAgain]

You have to read what 521.5.2 actually says - in particular read the bold heading.

Single core armoured cable can be used as indicated in 523.10. They must not however, have steel armouring - they can and do have aluminium armouring .