Running Cables in Safe Zones

[securespark]

Trying to find the birth of these regs.

In the 15th, regulation 523-20(a)-(d) cover safe zones. There is also regulation 523-20, which covers the running of cables under floors and above ceilings.

Looking back to the 14th Ed., B26 is 523-20's predecessor. But there is no equivalent in the 14th of 523-20(a)-(d).

AFAICT, having read most of the 14th, there are no safe zone regs in that edition.

Can anyone confirm?

 

[JohnW2]

AFAICT, having read most of the 14th, there are no safe zone regs in that edition. Can anyone confirm?

Hopefully someone may be able to answer your question.

As a supplementary question, I remember being told by an electrician (quite probably when he was "doing it"), decades ago, that it was acceptable to have a buried cable running 'diagonally', provided that it was in straight line between two visible accessories - which didn't seem all that unreasonable to me at the time. I therefore wonder whether there has ever been a regulation which 'allows' that - or, at least, whether there was ever a time when that was a common belief/practice?

Kind Regards, John

 

[securespark]

Depending on how many decades, that could be right. It would seem there were no "safe zone" rules in the 14th.
But the 15th certainly had strict rules around this.

 

[JohnW2]

Depending on how many decades, that could be right. It would seem there were no "safe zone" rules in the 14th.

I suppose I must be thinking of late 60s or 70s.

But the 15th certainly had strict rules around this.

... and didn't allow 'diagonal' routes between two visible accessories?

Kind Regards, John

 

[securespark]

From the 15th Edition:

523-20(a) Where a cable is to be concealed within a wall or partition its method of erection shall comply with Regulation 523-20(b) or 523-20(c) or its construction shall comply with Regulation 523-20(d), as appropriate.

523-20(b) The cable shall be installed within 150mm of the top of the wall or partition or within 150mm of an angle formed by two adjoining walls or partitions.

523-20(c) Where the cable is connected to a point or accessory on the wall or partition, the cable may be installed outside the zones permitted by Regulation 523-20(b) only in a straight run, either horizontally or vertically from the point or accessory.

523-20(d) Where compliance with Regulation 523-20(b) or 523-20(c) is impractical, the cable shall be of a type incorporating an earthed metallic covering complying with the requirements of these Regulations for a protective conductor of the circuit concerned, or the cable shall be enclosed in earthed conduit, trunking or ducting satisfying the requirements of these Regulations for a protective conductor.

 

[securespark]

So, no it did not!

 

[securespark]

By the time I'm 90, I hope to have duplicated the 14th and 15th Eds on this site!!

 

[JohnW2]

So, no it did not!

Indeed not. In fact, from what you've quoited, it looks as if the 15th was not significantly different from 18th in this respect. In a way, that makes sense - since one really needs 'safe zones' (or whatever one chooses to call them) to remain unchanged for decades if they are to serve the intended purpose.

Kind Regards, John

 

[JohnW2]

By the time I'm 90, I hope to have duplicated the 14th and 15th Eds on this site!!

You seem to have made a pretty good start

Kind Regards, John

 

[securespark]

 

[securespark]

Revisiting this one in light of the more recent thread on safe zones.

Actually, the 15th Ed. DOES allow diagonal routing, as long as the cable is protected by earthed conduit or covering, as per 523-20(d).

 

[JohnW2]

Revisiting this one in light of the more recent thread on safe zones. ... Actually, the 15th Ed. DOES allow diagonal routing, as long as the cable is protected by earthed conduit or covering, as per 523-20(d).

... but that doesn't differ from 17th or 18th (or 16th) editions, does it? - you seem to be talking about the required protection of cables when they are not in 'safe zones' (if/when such zones actually existed), aren't you?

Kind Regards, John

 

[securespark]

I posted that because I wanted anyone who came here looking up "safe zones" to get the right information. EG, someone may end up here wondering if the work done in their kitchen was to regulation. Yes, 523-20(d) does talk about protecting cables outside of the safe zones.
But that goes hand in hand with cables inside safe zones.

And I wanted to be certain that anybody reading this was not confused by:

... and didn't allow 'diagonal' routes between two visible accessories?

I know you meant something like "... and didn't allow 'diagonal' routes between two visible accessories to be included in the safe zones"

But it sounds like we were agreeing that the 15th Ed. did not allow it at all.

Just a bit of clarification, that's all!

 

[JohnW2]

I posted that because I wanted anyone who came here looking up "safe zones" to get the right information. EG, someone may end up here wondering if the work done in their kitchen was to regulation. Yes, 523-20(d) does talk about protecting cables outside of the safe zones. .... But that goes hand in hand with cables inside safe zones.
And I wanted to be certain that anybody reading this was not confused by: .... I know you meant something like "... and didn't allow 'diagonal' routes between two visible accessories to be included in the safe zones" .... Just a bit of clarification, that's all!

Fair enough. As the person who's questions really started this, I feel inclined to try to 'clarify the clarification', since I think there may still be some scope for some people to get confused.

As far as I can make out (and please correct me if you think I'm wrong), I think the situation is quite simple, and that nothing has really changed since the aspects of the regs we are discussing first appeared some 35 years, namely ...

1... Prior to implementation of 15th edition (1981-85), there were no explicit 'rules' about buried cables, the closest being the vague requirement that cables should be adequately protected against mechanical damage "in normal service" - and it's not clear (at least, not to me) as to whether 'normal service' was intended include attacks with drills, screws, nails etc.

2...Ever since then (hence throughout 15th, 16th, 17th & 18th eds.) there has been an essentially unchanged/unchanging provision for cables to be buried without mechanical protection (e.g. steel conduit) or an earthed covering in the specified 'zones'. Although we speak of them as 'Safe Zones' (which I personally regard as a misnomer - certainly for anyone with a drill, nail or screw in their hand!), I don't think that any edition of the regs has ever used or mentioned that term (merely 'zones').

3...Those zones consist of, and always have consisted of, the top 150mm of walls and the 150mm within the angle formed by two adjacent walls , and straight cable runs which are aligned horizontally or vertically with visible accessories. These zones have never included diagonal routes between accessories.

Do you agree with all that?

One point perhaps worthy of comment/question is that most people seem to regard the 150mm zone created by the angle between two adjoining walls as applying only to 'internal corners', whereas it would seem that the wording of the regulations, from 15th through to 18th eds., could probably be interpreted as also applying to 'external corners'. What do people think about that?

Kind Regards, John

 

[foxhole]

I've never come across any cable protection that would prevent my drill going straight through it, so while theory seems reasonable in practice common sense and caution should prevail.