My Complete DIY Rewire

skotl · 22 Feb 2015

...I don't always see eye-to-eye with b-a-s but I would ask where are the mods on this. They should be more active in splitting clearly off-topic discussions.

And the older-hands should know better, and create new academically focused threads.

Nozzle · 22 Feb 2015

They're like a bunch of tech college lecturers out-doing each other in the staff room over a cup of coffee with custard cream. All sat in their 1970's decor staff room on easy chair, Teaching Times on the table, a large set of dusty unloved textbooks on the shelf and the leather patches on their corduroy jacket elbows needing to be replaced for the third time. Busy arguing about the finer points of use of Comic Sans in the wider media, why won't someone think of the children, and of course the part P regs. Thrilling stuff!!!

Nozzle

PreferNotToDieOrBurn · 22 Feb 2015

skotl said:
The clearly incompetent and irrational OP

The OP is so magnificently out of his depth that I would have thought there would be enough material in trying to address his failings.

Please point out anything which isn't safe and/or to regs. That's all I ask. I'm not here for best practice advice on using plastic conduit as opposed to hot glue - I'm doing what works for me.

There is a difference between incompetent and not professional - I am not doing a professional job perhaps, but I'm also not incompetent.

Please point out anything which isn't safe and/or to regs. If you can't do that, then I'm clearly not failing as magnificently as you've made out.

PreferNotToDieOrBurn · 22 Feb 2015

JohnW2 said:
PreferNotToDieOrBurn said:

I do have another situation where 2.5mm cable have been designed to run in the same chase as a light switch and without a socket on the wall. In this case would I be best running the 2.5mm cables through the back box? Making it impossible to remove the light switch without noticing the other cables?

Click to expand...

Through the box is better than not through the box, but many/most people would still not consider it as being compliant with the regs. It's not just a case of 'noticing' that the cables are present when one takes the light switch off - someone could theoretically remove the light switch and 'plaster in' the back box, leaving th 2.5mm² cables still buried in the wall, but without anything visible to create a safe zone for them.

Couldn't you connect a socket to the 2.5mm² cables somewhere along their length, thereby creating a safe zone for the cables?

Kind Regards, John

I'd appreciate a few more comments on this. You say "many/most people" which makes me think there are differing views on how to classify it.

My understanding is that the 2.5mm cables would be installed in a safe zone and only when/if the light switch is removed they wouldn't comply with regulations. A safe zone either exists, or doesn't exists, it's in a binary state. Also the likelihood of the light switch being removed is very low.

I would have thought there is a similar risk of wires not being in a safe zone if any accessory is removed/plastered over. Surely it's the responsibility of the person doing to work to ensure after they make a change the installation still complies? (For example imagine a cable runs from room 1, through room 2, into room 3. For some reason the socket in room 2 is removed and the wires now run straight through, no longer in a safe zone in room 2. This is the fault of the person removing the accessory, not a fault in the design.)

What about ring final return paths which have to take the same route as the first half of the loop? (I've got a few of those)

I'm interested to see what people think on this.

And I imagine the recommendation, JownW2, is therefore to add mechanical protection as per BS7671 for cables not run in a safe zone and within 50mm of the surface?

Thank you

PreferNotToDieOrBurn · 22 Feb 2015

PreferNotToDieOrBurn said:
JohnW2 said:

PreferNotToDieOrBurn said:

I do have another situation where 2.5mm cable have been designed to run in the same chase as a light switch and without a socket on the wall. In this case would I be best running the 2.5mm cables through the back box? Making it impossible to remove the light switch without noticing the other cables?

Click to expand...

Through the box is better than not through the box, but many/most people would still not consider it as being compliant with the regs. It's not just a case of 'noticing' that the cables are present when one takes the light switch off - someone could theoretically remove the light switch and 'plaster in' the back box, leaving th 2.5mm² cables still buried in the wall, but without anything visible to create a safe zone for them.

Couldn't you connect a socket to the 2.5mm² cables somewhere along their length, thereby creating a safe zone for the cables?

Kind Regards, John

Click to expand...

My understanding is that the 2.5mm cables would be installed in a safe zone and only when/if the light switch is removed they wouldn't comply with regulations. A safe zone either exists, or doesn't exists, it's in a binary state. Also the likelihood of the light switch being removed is very low.

Just a further point on this. "Where an accessory on the reverse side of the wall can be easily determined, e.g. through a door or archway, and the wall or partition depth is 100mm or less, then the horizontal and vertical zones to that accessory apply to both rooms"

What would be the point of this unless safe zones were available for other wires not specifically connected to an accessory within that safe zone? On the reverse side the cable is (assume to be) more than 50mm deep hence not requiring a safe zone, so it's not defined as a safe zone for the benefit of that cable. So what would be the point of this rule, if not to allow safe zones to be used for other wires?

A design can always be modified, and any modification can make the design unsafe, so is it the design that needs to follow safe zones, or each specific cable?

edit: I might be thinking about this all wrong as it applies to walls "less than" 100mm thick, so possibly a wall 50mm thick. Hurm....

bernardgreen · 22 Feb 2015

PreferNotToDieOrBurn said:
. "Where an accessory on the reverse side of the wall can be easily determined, e.g. through a door or archway, and the wall or partition depth is 100mm or less, then the horizontal and vertical zones to that accessory apply to both rooms"

What would be the point of this unless safe zones were available for other wires not specifically connected to an accessory within that safe zone?

Think of the "safe zones" as zones where it is NOT safe to drill holes into the wall. Cables may be safe in those zones and that is the misleading description of them as safe zones.

JohnW2 · 22 Feb 2015

skotl said:
...I don't always see eye-to-eye with b-a-s but I would ask where are the mods on this. They should be more active in splitting clearly off-topic discussions.

I agree, and I've said this many times before. The moderation in this forum is generally very good but, compared with many other forums I'v been involved with, and ones in which I have 'moderated', it seems that little attention is paid to thread splitting.

skotl said:
And the older-hands should know better, and create new academically focused threads.

I also agree with that, and I'm obviously one of the major offenders. Some of us do try to start new threads when tangential discussions arise, but it's not easy to remember to do that and, worse, by the time one realises the need, it's really too late for anyone but the mods to do anything satisfactory about it.

Kind Regards, John

JohnW2 · 22 Feb 2015

PreferNotToDieOrBurn said:
I'd appreciate a few more comments on this. You say "many/most people" which makes me think there are differing views on how to classify it. ... My understanding is that the 2.5mm cables would be installed in a safe zone and only when/if the light switch is removed they wouldn't comply with regulations. A safe zone either exists, or doesn't exists, it's in a binary state. Also the likelihood of the light switch being removed is very low.

Since many of the regs stop short of being totally clear/explicit or exhaustive, there is often a need for 'interpretation' - and that means that there will be differing opinions. As you say, in your example, there is only a risk if the light switch is removed, and I agree that the likelihood of that happening is very low. However, many of the requirements of the regs relate to situations which are very improbable, but not impossible.

PreferNotToDieOrBurn said:
I would have thought there is a similar risk of wires not being in a safe zone if any accessory is removed/plastered over. Surely it's the responsibility of the person doing to work to ensure after they make a change the installation still complies?

That's the point. If there is a requirement (as I believe there is) that an accessory only creates a safe zone in relation to a cable which is connected to the accessory (or behind which accessory it is joined), then there is no (compliant) way of removing the accessory without removing (or, at least, de-energising) the cable - one clearly can't remove an accessory and 'plaster over' the end of a live cable (or a joint in the cable). It's really just common sense.

PreferNotToDieOrBurn said:
And I imagine the recommendation, JownW2, is therefore to add mechanical protection as per BS7671 for cables not run in a safe zone and within 50mm of the surface?

That's the 'last resort' solution, but it is easier to try to find a way of installing the cable in a safe zone, even if that involves installing an 'unnecessary' accessory.

Kind Regards, John

JohnW2 · 22 Feb 2015

Moderator 11 said:
just keep arguing among yourselves. Better one futile thread than two. icon_wink.gif

FWIW, I disagree. IMO, the two (or more) split threads would be 'futile' in very different ways, hence some might possibly be of interest to (and certainly more readable by) some people - and some of the split threads might not be regarded as 'futile' at all by some people.

Kind Regards, John

AndyPRK · 22 Feb 2015

Threads about rings v radials tend to just go round and round with little agreement

JohnW2 · 22 Feb 2015

AndyPRK said:
Threads about rings v radials tend to just go round and round with little agreement

They would, wouldn't they

However, as with all such situations, if there is 'little agreement', that's a pretty good indication that that there is no 'right or wrong' answer.

Kind Regards, John

333rocky333 · 22 Feb 2015

How do you thank Mod 11

JohnW2 · 22 Feb 2015

333rocky333 said:
How do you thank Mod 11

I think what you've just written is the closest you can get to thanking him/her!

Again FWIW, I still think that leaving messy multiple-topic threads un-split is non-ideal, whether or not the discussions are 'futile' in the eyes of some, but maybe that's just me! When I've 'moderated' in forums, probably the greatest single aspect of the work was splitting (and sometimes combining) threads!

Kind Regards, John

ban-all-sheds · 24 Feb 2015

JohnW2 said:
However, as with all such situations, if there is 'little agreement', that's a pretty good indication that that there is no 'right or wrong' answer.

I fear that appears to be the case because so many people adopt the position of "that's the way it's been done because that's the way it's always been done and it's always been done that way because that's the way it's done".

I genuinely believe that if we had never had ring finals then a proposal to introduce them would be rejected on the grounds that they are not necessary, or not necessary enough given the problems and safety risks that come with them.

I also believe that people who claim they genuinely think that the {BSI|IET|JPEL/64} would say "brilliant idea - let's do it" have either failed to apply any logic to the question or are just being deliberately perverse and contrary for their own pathetic amusement.

Given the changes that keep being introduced to the Wiring Regulations for increasingly marginal improvements in safety it beggars belief that they would countenance the introduction of a circuit design so beset with potentially serious safety problems.

So if they re unnecessary and flaky now, then why not start to get rid of them now? Historical precedent is not a reason to persist with something which should no longer be done.

JohnW2 · 24 Feb 2015

ban-all-sheds said:
I genuinely believe that if we had never had ring finals then a proposal to introduce them would be rejected on the grounds that they are not necessary, or not necessary enough given the problems and safety risks that come with them. ... Given the changes that keep being introduced to the Wiring Regulations for increasingly marginal improvements in safety it beggars belief that they would countenance the introduction of a circuit design so beset with potentially serious safety problems.

That is very probably true

ban-all-sheds said:
So if they re unnecessary and flaky now, then why not start to get rid of them now? Historical precedent is not a reason to persist with something which should no longer be done.

You would obviously have to ask them. They might feel that abolition of ring finals (which would probably take 50+ years to complete) would not result in enough marginal improvement in safety to be justified even in terms of their increasingly exactly requirements. I would be surprised if anyone here could cite any safety issue they have encountered which arose because the circuit was a ring final- and, of course, there is the 'balancing' fact (as mentioned by stillp) that the redundancy of CPCs in a ring will undoubtedly have occasionally resulted in the avoidance of a 'safety issue'.

In reality, given that the great majority of ring finals are wired with Method C 2.5mm² cable, I would have thought that the probability of any significant safety issues arising (as compared with the corresponding radials) would be incredibly small - maybe even less than the improvement in safety due to the CPC redundancy.

Kind Regards, John

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