Reference Meathod for Timber Frame

[Silly Sausage]

Installation methods aside, I think section 523.9 is relevant here.
A derating factor of 0.51 is applicable.

 

[Rpa07]

We are not talking of a particular circuit type here and I agree that lighting and power circuits would not be an issue due to true usage but taking your shower that has a cable route through a full height wall and a little bit more, if 10mm
64amp clipped direct
32amp just stuffed in't middle of it all
44amp in some sort of conduit in't middle of all the insulation.
That's the difference between a nice powerful warm 9.5kw for me and a piddly 7.5 kw for you. There is something in it for fixed loads.

 

[westward10]

We are not talking of a particular circuit type here and I agree that lighting and power circuits would not be an issue due to true usage but taking your shower that has a cable route through a full height wall and a little bit more, if 10mm
64amp clipped direct
32amp just stuffed in't middle of it all
44amp in some sort of conduit in't middle of all the insulation.
That's the difference between a nice powerful warm 9.5kw for me and a piddly 7.5 kw for you. There is something in it for fixed loads.

Am I missing something, how does the ccc increase by 12A because the cable is contained in conduit.

 

[Rpa07]

Look in the tables - it gets reduced from 64 to 44 if contained and in insulation but reduced from 64 to 32 if placed just in insulation. Come on westward did you have a heavy lunch?

 

[Wilko]

Putting on my tin hat, I reckon the good book says no advantage for using conduit in insulation, advantage comes from clipping cable or conduit to the wall. Little pic to illustrate :

 

[westward10]

Okay you are looking at Table 4D5. Your 44A comes from column 7, enclosed in conduit in an INSULATED WALL. Your 32A comes from column 5, in a stud wall with THERMAL INSULATION. Column 7 does not refer to thermal insulation it refers to an insulated wall. None of the Installation Methods in that table refer to cables in conduit surrounded by thermal insulation. Your sums are incorrect.

 

[westward10]

Putting on my tin hat, I reckon the good book says no advantage for using conduit in insulation, advantage comes from clipping cable or conduit to the wall. Little pic to illustrate :

View attachment 33743

Was just looking at the same thing, but it refers to a thermally insulated wall much like column 7 Table 4D5. So from your shown Table you would refer to column 2 in 4D2A which give an amp or so is the same as 4D5.

 

[Leesparkykent]

Okay you are looking at Table 4D5. Your 44A comes from column 7, enclosed in conduit in an INSULATED WALL. Your 32A comes from column 5, in a stud wall with THERMAL INSULATION. Column 7 does not refer to thermal insulation it refers to an insulated wall. None of the Installation Methods in that table refer to cables in conduit surrounded by thermal insulation. Your sums are incorrect.

Yes it does. Column 7 reference method A* for full installation method refer to table 4A2 number 2 but for flat twin and earth cable.

4A2 number 2 multicore cable in conduit in a thermally insulated wall with an inner skin having a thermal conductance of not less than 10 W/m2K c. So you use reference method A to determine CCC.

 

[westward10]

Yes it does. Column 7 reference method A* for full installation method refer to table 4A2 number 2 but for flat twin and earth cable.

4A2 number 2 multicore cable in conduit in a thermally insulated wall with an inner skin having a thermal conductance of not less than 10 W/m2K c. So you use reference method A to determine CCC.

I can see your point but it does not refer to thermal insulation but a thermally insulated wall. Not going to cross swords here my initial confusion was from an earlier post which stated containing the cable in conduit would increase the ccc, and I assume the poster was misguided by Table 4D5.

 

[Midwest]

To add my measly morsel, 7.1 Reference method A, is described as 'wall consists of outer weatherproof skin' etc etc, which suggests to me is for an external wall. Whereas Reference method 102 - 103 are referring to stud walls, and placing in conduit will have no beneficial or detrimental effect to ccc, apart from bunching of cables?

OR should I just carry on cooking me piece of beef

 

[Leesparkykent]

Back to the op If the cables clipped to the stud and covered by insulation then ref method 103. If cable is touching inner wall surface then ref method 102...That's hope its 102.

 

[westward10]

Back to the op If the cables clipped to the stud and covered by insulation then ref method 103. If cable is touching inner wall surface then ref method 102...That's hope its 102.

We are unanimous on that.

 

[Pete999]

We are unanimous on that.

Yes Mrs Slocombe

 

[Midwest]

Beef in. Most of the wood stud work installations I've seen or done have the cables down the middle of said stud work and would never be close to the inner wall surface.

 

[Pete999]

Beef in. Most of the wood stud work installations I've seen or done have the cables down the middle of said stud work and would never be close to the inner wall surface.

No Mate run it in some trunking or conduit that will increase the ccp of the cable.

 

[Leesparkykent]

Beef in. Most of the wood stud work installations I've seen or done have the cables down the middle of said stud work and would never be close to the inner wall surface.

 

[Midwest]

No Mate run it in some trunking or conduit that will increase the ccp of the cable.

Spuds in. You've confused me now Pete, thought the whole thrust of this debate, suggest no benefit of putting cables in conduit in insulated stud wall?

 

[Pete999]

Spuds in. You've confused me now Pete, thought the whole thrust of this debate, suggest no benefit of putting cables in conduit in insulated stud wall?

Trying to be sarcastic, but obviously it didn't work

 

[westward10]

Trying to be sarcastic, but obviously it didn't work

 

[Midwest]

Trying to be sarcastic, but obviously it didn't work

Parsnips in, carrots in & brussels prepped, gravy slowly bubbling. Sorry Pete, got me BS7671 and me 'Fabulous Fanny' cookbook open at the same time, and cough, couple of vinos in. Got it now though