Good Old Delroy, he gets all the best Jobs :)

[mainline]

Think he means STRAMETT BOARD

He doesn't like to be criticised that much does he?

His son does all the web stuff, and I'm guessing he would find it difficult to tell his father that even after 40 years experience in his job that he's still blissfully ignorant.

 

[mainline]

ah, those beads that get pumped into cavities sometimes, fair enough.

I only asked because in the video the room has a short wall all the way round, presumably the cavity is open at the top, and i guess with rockwool or celotex in the cavity, so running cables through it would seem a reasonable way to do it in this instance, same as you see in alot of conservatories. Delroy was 'teaching' the new lad and said you weren't allowed to do that but he didn't know why......

I agree in this instance, using the cavity would be reasonable.

 

[Mike Johnson]

I'm sorry, but using the cavity to run cables is not reasonable or acceptable in any circumstance, possible bridging of the cavity tie which has a drip on it to allow moisture to drip to the bottom of the cavity, but any penetration of the skin/insulation will introduce a thermal bridge, in a conservatory the correct way would be to run conduit in the floor, if the inside skin is fair faced brick then the back of the brick on the inside face is chased out to provide a passage for the conduit.

 

[mainline]

I'm sorry, but using the cavity to run cables is not reasonable or acceptable in any circumstance, possible bridging of the cavity tie which has a drip on it to allow moisture to drip to the bottom of the cavity, but any penetration of the skin/insulation will introduce a thermal bridge, in a conservatory the correct way would be to run conduit in the floor, if the inside skin is fair faced brick then the back of the brick on the inside face is chased out to provide a passage for the conduit.

My point would be that in this instance he can ensure that no breach would exist as it's open and low, giving easy access.

I have no idea of the layout but assume the demand isn't going to be very high, so depending on the layout would think about a radial/s rather than the ring final.

 

[Mike Johnson]

Still the point of introducing a thermal bridge unless the cable can be placed on the inside face of the cavity insulation.

 

[mainline]

Still the point of introducing a thermal bridge unless the cable can be placed on the inside face of the cavity insulation.

The cable would have to be on the inside face for the socket feeds, and I can't think of any reason for any of the cables to be bridged across the cavity.

 

[DPG]

The cable would have to be on the inside face for the socket feeds, and I can't think of any reason for any of the cables to be bridged across the cavity.

If cables are dropped into a cavity then they will contact the inner and outer walls several times, causing bridges.

 

[mainline]

If cables are dropped into a cavity then they will contact the inner and outer walls several times, causing bridges.

How would a 2.5 drop down the inner skin of a cavity cause a bridge several times the wall is only about 3 foot high and the sockets would be above 450 mm off the floor not much of a drop'

 

[Mike Johnson]

The cable would have to be on the inside face for the socket feeds, and I can't think of any reason for any of the cables to be bridged across the cavity.

If the insulation is already in place i.e. positioned whilst building the brickwork, it would be too easy to just drop the cable down the void, then penetrating the insulation to access the pattress box, this would cause a thermal bridge between the temperature of the cavity and the inside of the room.

 

[DPG]

How would a 2.5 drop down the inner skin of a cavity cause a bridge several times the wall is only about 3 foot high and the sockets would be above 450 mm off the floor not much of a drop'

I assumed he would take them horizontally across the cavity as well.

 

[mainline]

If the insulation is already in place i.e. positioned whilst building the brickwork, it would be too easy to just drop the cable down the void, then penetrating the insulation to access the pattress box, this would cause a thermal bridge between the temperature of the cavity and the inside of the room.

That's right it would be too easy to drop it in the void but that wall is so short a drop it would hardly be any work to avoid a bridge, he may even have enough room to get behind the dot and dab.
Like I said in this instance, i think it would be reasonable.

 

[mainline]

I assumed he would take them horizontally across the cavity as well.

The cable would obviously have to travel horizontally.

 

[DPG]

The cable would obviously have to travel horizontally.

I know. But you said there would only be a short drop.

 

[mainline]

I know. But you said there would only be a short drop.

Yes if the run was across the top of the wall and dropped to each socket.

 

[DPG]

Yes if the run was across the top of the wall and dropped to each socket.

Well, true. The point remains though, it is bad practice to run wiring in the cavity.

 

[Mike Johnson]

That's right it would be too easy to drop it in the void but that wall is so short a drop it would hardly be any work to avoid a bridge, he may even have enough room to get behind the dot and dab.
Like I said in this instance, i think it would be reasonable.

You are now introducing a totally different scenario, if the construction is dot and dab on the inside skin why is dropping the cable down the cavity even being considered.

 

[DPG]

That's right it would be too easy to drop it in the void but that wall is so short a drop it would hardly be any work to avoid a bridge, he may even have enough room to get behind the dot and dab.
Like I said in this instance, i think it would be reasonable.

You are now saying a bridge should be avoided. We are in agreement.

 

[mainline]

Well, true. The point remains though, it is bad practice to run wiring in the cavity.

This is where Mr spark gives a quote of many £100s of pounds more to dig up his floors or hack his walls to bits and Mr bob the DI gets the work.

 

[Mike Johnson]

This is where Mr spark gives a quote of many £100s of pounds more to dig up his floors or hack his walls to bits and Mr bob the DI gets the work.

I did not know that Detective Inspectors did electrical work.

 

[mainline]

You are now introducing a totally different scenario, if the construction is dot and dab on the inside skin why is dropping the cable down the cavity even being considered.

I'm not introducing a scenario at all, we were discussing the Delroy instance, if you watched the video you would know that he said it was dot and dab.