Running lighting circuits in the loft space.

[Amp David]

When running lighting cables in the loft space, they can be clipped to the side of the joists no problem. When the cable then needs to be run at right angles to the joists, is it best pratice to drill the joists to pass the cable through or run over the top of them.

Cheers for the advice guys.

 

[Engineer54]

- E54, You'll see holes and notches through most joists in older houses, but not, generally, in the loft !

Read my post again, did i say or mention loft joists?? Some of those older houses have loft joists, at least as big if not bigger in some cases than it's floor joists!! lol!!!

 

[ackbarthestar]

Read my post again, did i say or mention loft joists?? Some of those older houses have loft joists, at least as big if not bigger in some cases than it's floor joists!! lol!!!

I did, and you applied your argument generically whether drilled or notched, leaving it open !

edit: Plumbers don't usually notch or drill joists in loft spaces, unless they are bonkers

 

[ipf]

Once came across a situ where a loft joist had a 5'' complete cut out to allow the install of a recessed fitting. To make matters worse, a repeat on the same joist a couple of yards away. Probably even have had the mice cr****n' 'emselves.

 

[Engineer54]

I did, and you applied your argument generically whether drilled or notched, leaving it open !

edit: Plumbers don't usually notch or drill joists in loft spaces, unless they are bonkers

But i wasn't referring to your post, ...just that i'm not that quick at typing as most!!

How many plumbers do you know, ...that aren't Bonkers?? lol!!!

 

[chris murphy]

But i wasn't referring to your post, ...just that i'm not that quick at typing as most!!

How many plumbers do you know, ...that aren't Bonkers?? lol!!!

"Hello Engineer54",


I realise that You are Joking about Plumbers being Bonkers - words to that effect - But I have often seen references to Plumbers [Sometimes meaning Heating Installers / Engineers] that were less than Complimentary on the Forum.

I have definitely noticed that this does NOT seem to happen on Plumbers Forums regarding Electricians being even `Mildly Insulted`/ Refereed to in a less than Complimentary way.

Do You happen to know WHY this `Insult Plumbers` theme seems to happen on here ?

I am NOT being Over Sensitive here - I would definitely NOT take these comments seriously - I just wondered WHY they seem to be made so often ?

Having started My Career with a Plumbing Apprenticeship and then continued with further Training and Exams in Heating & Ventilation - Gas Utilisation - Electrical Installation - Defined Scope for Gas Installers / Heating Engineers etc. I am Certain that the Extent / Content / Time Scale of Training and Exams that I have taken is At Least Equal to MOST of the Electricians on here.

So I would state that I am in NO Way a Tradesman / Engineer with `Lesser Training` in MY Industry than an Electrician has in theirs.

I realise that the Electrical Trade / Industry is a Highly Technical Trade / Industry.

I wonder Why is it that some Electricians SEEM to be intimating that Plumbing / Plumbers [inc. Heating Engineers / Installers] are somehow in a `Less Technical Trade` / Industry ?

Some of the comments that I have read on the Forum seem to be directed at `Plumbers` [although the topic might be about Central Heating] as being somehow `Inferior Tradesmen` - Or that Plumbing [inc. Heating ?] is a `Lesser Trade` - ?

I definitely don`t want this to start a Row - I am just Intrigued about the comments that I have seen on here about Plumbers.


Regards,

Chris

 

[telectrix]

1910 terrace, they're only 3 1/4" x 2 1/4".

Think it would be best to take them to the edge before running the m accross the loft.

Thanks for the advice.

in an old house with a proper roof support structure as opposed to the modern trusses, the ceiling joists are there solely to support the ceiling. these can be drilled sendibly without affecting the strength of the structure. however, i consider it good practice to route the cables towards the eaves when running at right angles to the joists. they are also then out of the way of mr. joe public's size 10's.

 

[mackers]

as said if trusses DO NOT DRILL . also as said try keep away from areas likley to be used for storage/access. also bare in mind loft insulation as this has a great detrement to the cable loadings. to be fare in the 20 + years i been a spark can,t remember joist been drilled in any loft ive been in ,most are 3x2 unless designed for dormers.
only time i drilled a truss was when i was an apprentice and got the mother of all -------ings LOL

 

[Dan the spark]

Wouldn't advise drilling the joists in a loft, just run the cables where no one is gonna tread or put things on:builder:

 

[Deleted member 26818]

The joist in lofts, are there as far as I'm aware, to fix the ceiling to.
They are not generally structural.
Yes crtain pre-formed trusses are structural, and it may not be possible to drill those.
I would would suggest contacting either building control or a structural engineer in such circumstances.
Remember, that cables if run through joists should be at leat 50mm from the surface of the ceiling or floor, or provided with mechanical protection.

 

[Specialist]

Long time since I studied this, but I think you'll find that the the Loft joists make up part of the Structural Integrity of the roof & holding the ceiling up is secondary.
The Trusses (Rafters) & ceiling joists make up an A frame structure, what happens when you remove the crossbar from an A frame & then load weight onto it ? It collapses.

 

[chris murphy]

in an old house with a proper roof support structure as opposed to the modern trusses, the ceiling joists are there solely to support the ceiling. these can be drilled sendibly without affecting the strength of the structure. however, i consider it good practice to route the cables towards the eaves when running at right angles to the joists. they are also then out of the way of mr. joe public's size 10's.

"Hello telectrix",


Without wanting to seem argumentative - even in the example that you mention where the Ceiling Joists are NOT part of the Roof Structure - would it not be the SIZE of the `Ceiling Joists` that SHOULD prevent People Drilling or Notching them ?

As in My previous example where the Ceiling Joists were a `Typical Size` of approx. 95mm X 47mm - How could it EVER be justified to Drill these Ceiling Joists ? - a 20mm or 25mm Hole in the Centre of a 95mm piece of Timber - ?


Chris

 

[High Tower]

Chris,

There will always be a amount of bitching about other trades no matter what!!, and plumbers are probably the closest to us in the job they do, and often plumbers are on site for first and second fix around the same time as us.

on the same note, for every good conciencious plumber, there are 5 more arrogant careless clowns that have no clue about anything other than pipes!!. how many times do we have to have cables drilled and screwed by muppets with no clue or knowledge of cable zones, had bonding conductors removed and not replaced, had pipes run close to cables then expected to move cables. and don't even start me on part p plumbers!

Chris, you are a exception to the rules mate! if more people took the interest and made the effort that you do!, we would be much better off

 

[41steve]

just installed mine, no problem. clip them to the side of the timbers. i dont want a pointed ceiling so i have studded from the apex to make a flat area in the roof, looks so much better an plenty of room to keep cables in the correct zones.

 

[ample current]

Getting away a little from how we get accross the joist in a loft space how do we run the cables with so much insulation in them, nowadays 300mm, so well above the tops of the joists? say any suggestions aof where to clip the cables here

 

[41steve]

the insulation i am using is iso super 10. its clipped to the underside of the joists. thats architects 4 ya! channel the cables?

 

[41steve]

the insulation i am using is iso super 10. its clipped to the underside of the joists. thats architects 4 ya! channel the cables?

those timbers have to carry the weight of the roof! i dont think an hole in a 4x2 would comply anyway.

 

[chris murphy]

Chris,

There will always be a amount of bitching about other trades no matter what!!, and plumbers are probably the closest to us in the job they do, and often plumbers are on site for first and second fix around the same time as us.

on the same note, for every good conciencious plumber, there are 5 more arrogant careless clowns that have no clue about anything other than pipes!!. how many times do we have to have cables drilled and screwed by muppets with no clue or knowledge of cable zones, had bonding conductors removed and not replaced, had pipes run close to cables then expected to move cables. and don't even start me on part p plumbers!

Chris, you are a exception to the rules mate! if more people took the interest and made the effort that you do!, we would be much better off

"Hello High Tower",

Thank You for your reply and your complimentary remarks about Me.

I realise that there can be conflict between our Trades because of the situation that You mentioned regarding being on Site at about the same times for our First and Second Fix Works - But I must have been Lucky as I have not Personally encountered any problems working on site with Electricians - obviously I have been Working with considerate Tradesmen and I am definitely considerate of their Works.

I definitely do think about the `Following Trades` - usually an Electrician - and also I would NOT want ANYONE to be able to Critisise anything about My Workmanship.


I would be `Horrified` to think that something that I did Carelessly either Damaged another Tradesman`s Work - Or affected the Installation of His Work in a Detrimental way !

Because I have previously had a lot of experience in taking on entire refurbishments where I would have been not only the Heating, Plumbing and Gas Installer but also the Main Contractor - So at no time would I want to do anything that would affect another Trades Work.

But I would have been VERY Considerate of other Trades Work / Cable Routes etc. [Guessed or Asked about] from the time of being an Apprentice.


I would guess that what You describe happens mostly on Domestic Refurbishments / Conversions etc. [?]

I have also had a fair bit of experience in Supervisory Positions on Site - with as many as 60 Plumbers - Heating Engineers & Apprentices - these were Contracts on Large Sites with obviously Electrical Contractors and all other Trades on Site.

I have NOT experienced much `Plumber / Electrician` Rivalry / Animosity on these Large Sites - Just problems over the Contract Programs putting the Two Trades into the same location at the same times.

I am Sorry to hear that some / most of the Electricians have had BAD Experiences with `Plumbers` while Working - Your Quote about there being a 5 to 1 ratio of Careless / Inconsiderate Plumbers to the Good / Considerate Plumbers is really Shocking [No Pun intended] to Me !


Thanks Again for your reply.

Regards,

Chris

 

[pushrod]

"Hello pushrod"


Without going to look at the British Standard or the Regulation that You have quoted I am fairly sure that what You quoted applies only to Floor Joists.
.

Hi Chris, if you do go to the reg i quoted ( i see the link i put in no longer works) you will see that it does in fact mention both floors and ceilings - as it does in the electricians guide to the building regs and GN1. It is now 522.6.100 in ammendment 1. The sensible thing is always to assess the situation and in lofts the prevalence of insulation would usually usually make it sense to look for an alternative route if you don't want to seriously derate your CCC.

 

[chris murphy]

Hi Chris, if you do go to the reg i quoted ( i see the link i put in no longer works) you will see that it does in fact mention both floors and ceilings - as it does in the electricians guide to the building regs and GN1. It is now 522.6.100 in ammendment 1. The sensible thing is always to assess the situation and in lofts the prevalence of insulation would usually usually make it sense to look for an alternative route if you don't want to seriously derate your CCC.

"Hello pushrod",

Thanks for letting Me know about the Regulation Detail.

This comment is NOT Me trying to be `Funny`/ Sarcastic - in ANY Way so Please don`t be offended - I would NOT have to look up ANY Regulation - Building Regulation or any other to decide that I would NEVER Drill or Notch ANY Joist or other Timber that was much less than approx. 200 mm Deep.

This Figure is based on an 8" Joist with a Notch of 25mm for a 22 mm Pipe - which is `No More than One Eighth of the Depth of the Joist` - obviously for practical purposes the 25 mm Notch might be a couple of Millimetres deeper to ensure that the Pipe does stay beneath the top of the Joist level - but still a very small percentage over that recommended Depth of Notch.

As I have known this figure for 40 Years - I cannot readily give a reference for it.

This is almost impossible to adhere to when you are running 28 mm Pipes - as the 8" Joist is the most prevelent Joist Depth - then the Joist will have to be Notched to perhaps 32 mm - Nothing else can be done in these circumstances - As Building Control would know and have to accept - Unless they insisted that the Joists were Reinforced by Laminating Ply onto the sides - which would be within their remit - BUT would be excessive in My opinion.

I know that when Drilling a Joist different figures apply in relation to the Hole Size / Depth of Joist - as when Drilling the `Neutral Axis` the `One Eighth of Joist Depth` does NOT Apply - But I would Personally NOT be wanting to Drill a Joist that was smaller than 200 mm Deep.


I also realise that Cable Routes / Considerations differ from those for Pipes when planning the route.


Our Professional Judgement would also allow Us to decide whether a Joist or other Timber could be Drilled or Notched WITHOUT a Risk of Structural Failure from Loads etc.


Regards,


Chris.


"Happy Christmas and New Year" - to You and All of the Members on the Forum

 

[Amp David]

I've always wondered how those joists manage to carry all that new insulation they stick up there nowadays :carolers: