Cables Running in Notches

[SYKRAPS]

Good Evening,

What do you guys advise on this if you are doing a MW and there are some cables running in notches?

There are no external influences involved but the cables "from a 16th edition install" are not more than 50mm from the floor board top on the circuit to be altered.

My gut feeling is to install mechanical protection where required in the form of galv plates, but is this factually correct IYO?

Thanks.

I should add that the alteration would be installed in line with the 17th edition in drilled holes more than 50mm from the joist top.

 

[Deleted member 26818]

Yes, you should provide mechanical protection if the cables are less than 50mm either from the top surface of the floor, or from the lower surface of the ceiling.
Could be a galv plate, or even a short length of galv conduit.

 

[GLENNSPARK]

Yes, you should provide mechanical protection if the cables are less than 50mm either from the top surface of the floor, or from the lower surface of the ceiling.
Could be a galv plate, or even a short length of galv conduit.

spin....
he protects his own work......so in this case it may require that the whole of this chase into joists is given the mechanical protection......but on the 16th?...(OP)....

 

[Deleted member 26818]

I'm assuming, the OP is intending re-using existing notches, rather than drilling new holes in virgin joists?

 

[SYKRAPS]

The installation to be altered was installed in 2002 thus 16th edition and was installed in what look like pre-existing notches "for some unknown but very lazy reason", my alterations will be installed using drilled holes in the joist centres thus greater than 50mm from the joist surface.

My question is whether you guys would want to bring the circuit in its entirity in line with the current edition of BS7671?

 

[SirKit Breaker]

You are only responsible for ensuring that whatever you do, complies with current regs. You are only going to do what you are getting paid to do, if you are not happy with anything on the existing installation, then mention it to your customer, and give him a price.

My car had an illegal tyre, and worn brake pads on its MOT, but it was otherwise OK. He brought the car back up to a legal and safe condition, but he didn't do it free of charge. I cant understand the mentality of Electricians who feel that they have to make everything fit the REGS! and do it all for free.

Cheers...........Howard

 

[Darkwood]

Things to consider if notches are existing and already quite deep it would be preferable to re-use rather than drilling holes if an alternative route cant be found as this would only further weaken the joist but with the guard plates for cable protection.
Structural integrity of the joist should be kept to a maximum and if its already been subject to a maniacs axe job then if you cant re-use you need to find alternate run drilled with a decent distance to prevent creating a weaker point than already exists

 

[Deleted member 26818]

You are only required to ensure that your work complies.
However if you want to bring the rest of the circuit up to date, there's nothing preventing you from doing so.

Just as an aside, you should note, that the 16th edition also required cables to be 50mm from either surface, incorporate an erthed sheath, be run in earthed conduit or trunking, or be provided with mechanical protection.
About the only real change, in the 17th, is that SELV circuits no longer have to be protected.

 

[SYKRAPS]

You are only required to ensure that your work complies.
However if you want to bring the rest of the circuit up to date, there's nothing preventing you from doing so.

Just as an aside, you should note, that the 16th edition also required cables to be 50mm from either surface, incorporate an erthed sheath, be run in earthed conduit or trunking, or be provided with mechanical protection.
About the only real change, in the 17th, is that SELV circuits no longer have to be protected.

I mentioned that the installation was installed whilst the 16th edition was in force to let you know the age of the installation, I was not suggesting that it was complient the way that it was installed.

 

[SYKRAPS]

You are only responsible for ensuring that whatever you do, complies with current regs. You are only going to do what you are getting paid to do, if you are not happy with anything on the existing installation, then mention it to your customer, and give him a price.

My car had an illegal tyre, and worn brake pads on its MOT, but it was otherwise OK. He brought the car back up to a legal and safe condition, but he didn't do it free of charge. I cant understand the mentality of Electricians who feel that they have to make everything fit the REGS! and do it all for free.

Cheers...........Howard

I would not do anything for free, but should compliance with current regs not be a consideration if changing the circuit characteristics IYO

 

[GLENNSPARK]

I would not do anything for free, but should compliance with current regs not be a consideration if changing the circuit characteristics IYO

if your interfierin with any work....present or otherwise....then anything you do should comply with the latest edition of the regs......including any additions/alterations to previous addition work....

 

[kingeri]

I was at a job recently where the joists were peppered with notches and holes from over the years, none of them in the right place to comply with current regs. Had I drilled new ones I think the place may have collapsed.

 

[Darkwood]

If the joists are already peppered with holes in none compliance then they need to be re-used and a guard plate fitted over them, structurally weakening the joist further would give far greater risk than a plumber nailing a rcd protected cable..... the OSG give guidance on where to drill holes in a new install with clean joists but a pre weakened joist need to be treated different and at the end of the day id rather another trade tripped the rcd than the ceiling falling in.

 

[Stroppy]

Talking of the guidance diagram in the OSG, is it acceptable to make oval holes in joists, as it shows, formed by joining up two adjacent holes? I ask as the diagram shows an oval, but the text only mentions holes, and that they need to be three diameters apart.

How many electricians actually adhere to these rules, ie holes 2 diameters apart, only within the 0.25-0.4 x span zone, etc? Most I have seen in my limited experience don't.

 

[kingeri]

Talking of the guidance diagram in the OSG, is it acceptable to make oval holes in joists, as it shows, formed by joining up two adjacent holes? I ask as the diagram shows an oval, but the text only mentions holes, and that they need to be three diameters apart.

How many electricians actually adhere to these rules, ie holes 2 diameters apart, only within the 0.25-0.4 x span zone, etc? Most I have seen in my limited experience don't.

I'd say no, simply because of the minimum distance between holes required?

 

[Stroppy]

I wish they'd change the diagram to show two correctly spaced holes, and not an oval then! I don't see the problem with a slot, really, as the centre part of the joist takes very little load, which allows 'engineered' joists like this to work.

 

[SirKit Breaker]

I would not do anything for free, but should compliance with current regs not be a consideration if changing the circuit characteristics IYO

Not necessarily. I will give you good example. Three or four years ago, i wired a conservatory up. It was built off the existing dining room, and i took a spur through the wall from an existing socket, which was part of the downstairs ring final, protected by a 3036 fuse. I installed a SFCU RCD type, and ran my cables as required, i did however ensure that the existing was up to the job of being added to, as this is our responsibility as you know.

My part of the install is 17th compliant, the existing install isn't. It was done like this because it was the easiest and cheapest fix. It would have been my preference to bring the ring final into the new age, but this would have involved a lot of grief and expense for the customer, and she had no real desire for me to destroy her kitchen or to pay me the £600 plus quid i quoted to replace CU etc.

Sometimes it is easier and cheaper to upgrade, and this is the preferred option wherever possible, but it is not a must do.

I hope i didnt come across as a bit sharp with my last post, but i find it frustrating that some people think that they are duty bound to correct every little non compliance, and quite a lot of large non compliances all for the princely sum of NO CHARGE. This is not and never will be the case. We have a duty of care to highlight any issues, and our consciences should promote this, but as the saying goes "we can only take the horse to the water, we cant make it drink"

Cheers.............Howard

 

[SYKRAPS]

I submitted the thread for constructive opinions both negative and positive, it is just a bone of contention on many insurance jobs that I attend.

Thank you all for your responses.

 

[HandySparks]

Talking of the guidance diagram in the OSG, is it acceptable to make oval holes in joists, as it shows, formed by joining up two adjacent holes? I ask as the diagram shows an oval, but the text only mentions holes, and that they need to be three diameters apart.

I think you've misunderstood the diagram. The shaded brown areas show the permited locations for notches and holes.

It's not an illustration of a notched or holed joist. If it was, you'd see the material thickness through the hole.

 

[Stroppy]

Ah I see what you mean. Trouble is, in the OSG version, it does show the shadow of the material thickness. I would have thought that a slot would be less weakening to the beam than the equivalent separate holes. Still, I,m no structural engineer, what do I know...?