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.

 

[ackbarthestar]

"Hello Again ackbarthestar",

Good Idea - But I believe that this Sheet Type Insulation is VASTLY Expensive - I would hate to think how much it would Cost - even for My Loft Space which is approx. 100 SQ. Metres - ?

I have also been told that the Sheets are NOT the Ideal Width for putting between the Rafters OR Joists - meaning a LOT of Off Cuts - On VERY Expensive Sheet Insulation !

Obviously If the Cost was Not a problem this type of Loft Insulation would probably be the BEST regarding what You mentioned about Boarding Over the Joists - The required Insulation Rating within an approximately 100 mm Joist Depth.



"Happy Christmas and New Year" to You.


Chris

Its about £60 per roll and 1 - 2 rolls with sealing tape will cover more of less any reasonably sized loft space... Its also good for space explorers !

 

[41steve]

soz, i was on about electrics for a loft conversion. i ment to say trusses an not joists!

 

[chris murphy]

Its about £60 per roll and 1 - 2 rolls with sealing tape will cover more of less any reasonably sized loft space... Its also good for space explorers !

"Hello ackbarthestar",

I am a bit confused now - when You mentioned the `Solid Foam` Insulation in this comment:

`I think there are other ways of insulating loft spaces and saving lots of space, such as the use of solid 'foam' cut to fit between the rafters and then covered with aluminum 'bubble wrap'



I thought that You meant the SHEETS of Foam Insulation - Perhaps sold in sizes something like 1200 mm X 600 mm X 50 mm - Foil Sheet applied to both sides.

It was this type of Sheet Insulation that I meant was VERY Expensive.


Chris

 

[robsparky1975]

soild foam,is it celotex you mean?

 

[Mr.Si]

soild foam,is it celotex you mean?

That is what I thought it meant too.

Sent from my Samsung Galaxy S II via Tapatalk

 

[chris murphy]

soild foam,is it celotex you mean?

"Hello robsparky 1975",


I was thinking of Kingspan Insulation - But I think that Celotex is a very similar product although I have never compared the Specifications of the 2 products.


Chris

 

[ample current]

Where is a good place to run cables in a loft space so they dont get buried in 300mm of insulation?, is it better to run them on the plaster board or clip to the lower edge of the ceiling joist or the top edge of the ceiling joist or lay over the insulation or use 300 miles of cable to right round the edges to go from the light fitting to the switch, at some point u surely have to go over the joists where they mayby troden on.

Cheers Mark

 

[ackbarthestar]

Where is a good place to run cables in a loft space so they dont get buried in 300mm of insulation?, is it better to run them on the plaster board or clip to the lower edge of the ceiling joist or the top edge of the ceiling joist or lay over the insulation or use 300 miles of cable to right round the edges to go from the light fitting to the switch, at some point u surely have to go over the joists where they mayby troden on.

Cheers Mark

IMO, the only place where cables run over the joists is where they unlikely to get in the way, such as tucked into the eaves, and always clipped to the side of the joists.
I used to know a chap who worked for a national building services company who never specified any lighting conductor size less than 1.5mm2 ........

 

[Mr.Si]

Sorry to dig this out again folks, but I went to the b&q place today to buy some loft panels.

Thought i would post what SOME of the instructions say:

1. You must re-route any cables that cross joists. Drill a hole on the centre line of the joist large enough for one cable. If more than one cable is involved, drill another hole on the centre line at least 50mm from the first.

Other instructions prior to this are to isolate any of the circuits which may be involved in the loft space.

Thought it may be good to post info about what Joe public are given as advice by manufacturers.

Sent from my Samsung Galaxy S II via Tapatalk

 

[ackbarthestar]

Sorry to dig this out again folks, but I went to the b&q place today to buy some loft panels.

Thought i would post what SOME of the instructions say:

1. You must re-route any cables that cross joists. Drill a hole on the centre line of the joist large enough for one cable. If more than one cable is involved, drill another hole on the centre line at least 50mm from the first.

Other instructions prior to this are to isolate any of the circuits which may be involved in the loft space.

Thought it may be good to post info about what Joe public are given as advice by manufacturers.

Sent from my Samsung Galaxy S II via Tapatalk

I suppose that's fine for the part time 'electrician' , probably quicker to hack the offending joist out of the way completely, then there's no problem of running it over the top

There must be a good read out there, somewhere such as, 'Thomas' electrical wiring schedules for tank engines'

 

[chris murphy]

Sorry to dig this out again folks, but I went to the b&q place today to buy some loft panels.

Thought i would post what SOME of the instructions say:

1. You must re-route any cables that cross joists. Drill a hole on the centre line of the joist large enough for one cable. If more than one cable is involved, drill another hole on the centre line at least 50mm from the first.

Other instructions prior to this are to isolate any of the circuits which may be involved in the loft space.

Thought it may be good to post info about what Joe public are given as advice by manufacturers.

Sent from my Samsung Galaxy S II via Tapatalk

"Hello Mr.Si",


What You quoted in your Post shows how Unreliable the `Instructions` from these Companies can be !

Apart from it NOT being the Correct thing to do - Drilling Holes in what are usually less than 100mm Deep Ceiling Joists - Even IF the Ceiling Joists were of a Bigger Size - there are Zones within which Joists are supposed to be Drilled - without the `Instructions` stating those Zones there should be NO mention of Drilling the Ceiling Joists.

Imagine Joe Public deciding to alter the Run of the cables in the Loft Space - as most Lights are in a central position in rooms - it would possibly follow that He would Drill holes in the Ceiling Joists across the Centre of the Joist span for each Room - If perceived to be the `Shortest Route` !

Obviously when re-routing cables it would sometimes be necessary to replace lengths of cable with longer ones to do this - some People would be prepared to do that - But I am fairly sure that if We asked someone who did not have any experience of the Electrical / Plumbing / Building Industries WHERE They would Drill the Ceiling Joists to run cables to Room Lights - Most of these People would be taking the Central [of the Room / Joist Span] Route !

Although Drilling the Ceiling Joists might not affect the `Holding` of the Ceiling - as mentioned previously If part of the Roof Structure this would be an Immediate Breach of the Building Regulations - and If in a Terraced Property this could affect more than the Property Roof where the Structure was compromised !


Chris

 

[Mr.Si]

Conti, the Manufacturer in this case and all other manufacturers need to have a rethink and get the install instructions changed to say "contact an electrician to reroute cables for you" maybe.

Sent from my Samsung Galaxy S II via Tapatalk

 

[ackbarthestar]

"Hello Mr.Si",


What You quoted in your Post shows how Unreliable the `Instructions` from these Companies can be !

Apart from it NOT being the Correct thing to do - Drilling Holes in what are usually less than 100mm Deep Ceiling Joists - Even IF the Ceiling Joists were of a Bigger Size - there are Zones within which Joists are supposed to be Drilled - without the `Instructions` stating those Zones there should be NO mention of Drilling the Ceiling Joists.

Imagine Joe Public deciding to alter the Run of the cables in the Loft Space - as most Lights are in a central position in rooms - it would possibly follow that He would Drill holes in the Ceiling Joists across the Centre of the Joist span for each Room - If perceived to be the `Shortest Route` !

Obviously when re-routing cables it would sometimes be necessary to replace lengths of cable with longer ones to do this - some People would be prepared to do that - But I am fairly sure that if We asked someone who did not have any experience of the Electrical / Plumbing / Building Industries WHERE They would Drill the Ceiling Joists to run cables to Room Lights - Most of these People would be taking the Central [of the Room / Joist Span] Route !

Although Drilling the Ceiling Joists might not affect the `Holding` of the Ceiling - as mentioned previously If part of the Roof Structure this would be an Immediate Breach of the Building Regulations - and If in a Terraced Property this could affect more than the Property Roof where the Structure was compromised !


Chris

Or as 133.1.3 states in BS7671

 

[chris murphy]

Or as 133.1.3 states in BS7671

"Hello ackbarthestar",


I think that I mentioned to one of the other Members in a previous Post that as I am NOT an Electrician and I do not carry out Electrical Work associated with My Heating Systems - even though I have completed the Defined Scope Electrical Part P Course and Assessment - I do not have a Copy of BS7671 `To Hand`.

I do have various Electrical Books - including the IEE [as was] On Site Guide - But that is not `Findable` at the moment.

Is there a reference in the Regulation / Reference that You quoted that you could put into words - a relevant Paragraph perhaps - ?

I would be interested in what You were quoting IF it is not Too Detailed to refer to - ?


Regards,


Chris

 

[ackbarthestar]

"Hello ackbarthestar",


I think that I mentioned to one of the other Members in a previous Post that as I am NOT an Electrician and I do not carry out Electrical Work associated with My Heating Systems - even though I have completed the Defined Scope Electrical Part P Course and Assessment - I do not have a Copy of BS7671 `To Hand`.

I do have various Electrical Books - including the IEE [as was] On Site Guide - But that is not `Findable` at the moment.

Is there a reference in the Regulation / Reference that You quoted that you could put into words - a relevant Paragraph perhaps - ?

I would be interested in what You were quoting IF it is not Too Detailed to refer to - ?


Regards,


Chris

133.1.3 read in conjunction with 134.1.1 briefly states that work done and equipment used outside of its standard needs to be assessed for risk by a competent person (all my words )