Table 4D5

[studentspark]

Table 4D5
Is this just for Twin and Earth, or would it also include 3 core and earth?

Or would you use table 4D2A for three core and earth (flat cable)

Table 4A2 says 'flat twin and earth' for installation methods

But Table 4D5 only says 'thermoplastic insulated and sheathed flat cable' so that could include 3 core and earth ?


Thanks

 

[Adam_151]

I would include the 3&E in the table for the T&E, but I think you'd struggle to find a situation where it actually mattered

 

[ericmark]

624B Twin & Earth LSZH Cable and 624Y Twin & Earth PVC Cable BS6004 both link to table 4D5 on the Batt Cables website, but since one cable is rated 90°C and the other 70°C this really does not make sense. But for the 624B we also have this

And the three core and two core version shows the same rating. But the installations methods 100, 101, 102, and 103 only seem to be shown on table 4D5 for 70°C cable, I would guess even if 624B Twin & Earth LSZH Cable can go to 90°C the question is can the material it is being run through?

As @Adam_151 says in real terms we rarely take cables to the limits, and some of the tables seem to take the attitude when bunched every cable will be taking its maximum, clearly with a 100 amp supply bunched cables often could never all take the maximum current, and those cables not at maximum will assist in cooling those which are. I have often found wires burnt with no insulation left, and have opened a loom so other cables within the loom can be inspected, and found the burnt cable within the loom appears undamaged.

In the main burnt cables seem to be related to the use of 110 volt supplies, transformers with a centre tap to earth used in error for example, so a line 2 to earth fault was not protected. Or the protective device was before the transformer, and again line to earth fault has taken twice the expected current due to centre tapping. It is rare to find overloading on 230 volt cables, what seems to be the problem is where cables are terminated, isolators for showers for example.

Today we are starting to see EICR done, however in commercial premises especially industrial with steel buildings which are subject to vibration, the EICR was part of a service, and terminal torque settings tested. Domestic has improved but it still has a long way to go.