Safe zone with exposed beams

[very_pointy_ears]

That's not necessary; the cable (if twin and earth) is good for 16A.

Even 1.0mm? It indeed is T+E, but I would have thought that would be 10A max.

 

[EFLImpudence]

No - 16A.

 

[securespark]

What do the regs say about 1 milli and "power" circuits?

[Duck]

 

[JohnW2]

No - 16A.

But an infamous Table in the regs says?

Kind Regards, John
Edit: typed too slowly again!

 

[EFLImpudence]

What do the regs say about 1 milli and "power" circuits? [Duck]

Table 52.3 say 1mm² non-sheathed and sheathed cable must not be used for power circuits.
1mm² non-sheathed and sheathed flexible cable may be used.

It is nonsense but that's what it says.

 

[securespark]

It's madness, I tell you, madness!

 

[JohnW2]

It's madness, I tell you, madness!

It gets 'worse', of course, since the CCC of 1mm² flexible cable is only 10A, not 16A.

Kind Regards, John

 

[securespark]

Has the world gone stark raving bonkers?

 

[very_pointy_ears]

It gets 'worse', of course, since the CCC of 1mm² flexible cable is only 10A, not 16A.

Kind Regards, John

<amateur speculation>Is the outside diameter of the bunch of strands in 1mm flex the same diameter as the solid core in 1mm T+E? If so, then 1mm flex core would have less cross sectional area of copper than solid core because of the gaps between the strands. Really you'd hope that was a true 1mm cross section of copper whether it be flex or solid core. I've no idea whether that's the case or not.</amateur speculation>

Regarding current ratings of T+E, I just found this: http://www.lightwiring.co.uk/lighti...-cables/twin-and-earth-cable-current-ratings/ which now makes me wonder what's so different about SWA. I bought some 16mm^2 three core SWA a while back to use as a sub main as I want a consumer unit in the garage/workshop to supply several circuits in the workshop and outbuildings. The cable is rated at 119A which is much more than the rating of 16mm T+E on that page I linked.

Edit: would the 119A rating be when it's being used to carry 3 phase with 3 live cores, instead of being used instead of T+E on a single phase supply?

 

[JohnW2]

<amateur speculation>Is the outside diameter of the bunch of strands in 1mm flex the same diameter as the solid core in 1mm T+E? If so, then 1mm flex core would have less cross sectional area of copper than solid core because of the gaps between the strands. Really you'd hope that was a true 1mm cross section of copper whether it be flex or solid core. I've no idea whether that's the case or not.</amateur speculation>

No, I'm afraid that your speculation is wrong. The 1mm² CSA relates to the total copper CSA, whether the conductor is solid or stranded.

Kind Regards, John

 

[JohnW2]

Regarding current ratings of T+E, I just found this: http://www.lightwiring.co.uk/lighti...-cables/twin-and-earth-cable-current-ratings/ which now makes me wonder what's so different about SWA. I bought some 16mm^2 three core SWA a while back to use as a sub main as I want a consumer unit in the garage/workshop to supply several circuits in the workshop and outbuildings. The cable is rated at 119A which is much more than the rating of 16mm T+E on that page I linked. Edit: would the 119A rating be when it's being used to carry 3 phase with 3 live cores, instead of being used instead of T+E on a single phase supply?

I really don't know where your 119A figure came from. For 3/4-core cables, the CCCs for 3-phase are actually a bit lower than for single phase. Per the tables in BS7671 which we generally work with, 70° 3-core 16mm² SWA, Method C, has a CCC of 89A for single-phase and 77A for 3-phase, whilst the corresponding figures for 90° SWA are 107A and 96A. For 70° 16mm² T+E, Method C, the CCC is 85A.

Kind Regards, John

 

[very_pointy_ears]

119A was the rating shown on the site when I bought the cable. They didn't state the conditions that were necessary for that rating, though. It was such a long time ago since I bought it that I can't remember where I got it from.

 

[securespark]

XLPE SWA is rated higher than PVC. But not as high as 119A. It's 94A.

 

[JohnW2]

XLPE SWA is rated higher than PVC. But not as high as 119A. It's 94A.

As I just wrote, 90° thermosetting 16mm² SWA appears to be 'rated' (Method C) at 107A for single-phase, 96A for 3-phase.

Kind Regards, John

 

[securespark]

Apologies
I was relying on a wholesaler's figures..