Current ratings of accessories

[stillp]

Delve no more! Sorry about the formatting, but below is the table from EN 60669-1of test current and conductor size for each current rating

Rated current A Test current A Nominal cross-sectional area of conductors mm2
1 1,5 0,5
2 3 0,75
4 5 1,0
6 8 1,5
10 13,5 2,5
16 20 4,0
20 25 4,0
25 32 6,0
32 38 10,0
40 46 16,0
45 51 16
50 57,5 16
63 75 25,0

 

[JohnW2]

Delve no more! Sorry about the formatting, but below is the table from EN 60669-1of test current and conductor size for each current rating

Rated current A Test current A Nominal cross
sectional area
of conductors mm2
1 1,5 0,5
2 3 0,75
4 5 1,0
6 8 1,5
10 13,5 2,5
16 20 4,0
20 25 4,0
25 32 6,0
32 38 10,0
40 46 16,0
45 51 16
50 57,5 16
63 75 25,0

Is that for cables, and is it a ~1 hour test? If so, again, passing the EN 60669-1 test would not (except for the first two in your table) indicate (necessarily) adequate protection from a Type B MCB with In equal to the stated 'rated' current.

Kind Regards, John

 

[stillp]

Sorry, it didn't look quite that bad in the preview. The first column is the rated current of the switch. Second is the 1hr test current, the 3rd is the csa of the conductors connected to the switch. That's another issue - the conductors connected to a 10A switch would usually be 1,5mm2, whereas the test is performed with 2,5mm2, so the switch would get even hotter with the smaller conductors.

 

[Porque223]

From the data the rated I is very nearly a linear function of the area so I^2 = f(circumference^2 = surface area^2)

Doubling I^2 should halve the insulation life which may relate to the test duration. This can be confirmed or disproved if anybody does tests at other than 1 hour.

 

[JohnW2]

Sorry, it didn't look quite that bad in the preview. The first column is the rated current of the switch. Second is the 1hr test current, the 3rd is the csa of the conductors connected to the switch. That's another issue - the conductors connected to a 10A switch would usually be 1,5mm2, whereas the test is performed with 2,5mm2, so the switch would get even hotter with the smaller conductors.

Ah, right, I understand. In that case, to pick out the most common examples, if the circuit is such that one feels that overload protection is required, then a '6A rated' switch is not necessarily adeqautely protected by a B6 MCB and similarly, '10A, '20A', '40A', '45A' and '50A' switches are not ncessarily adequately protected by a B10, B20, B40, B45 or B50 MCBs respectively.

However, FWIW, a 2A switch would be adequately protected by a B2 MCB (and a '1A' one by a B1)

Interesting

Kind Regards, John

 

[JohnW2]

From the data the rated I is very nearly a linear function of the area so I^2 = f(circumference^2 = surface area^2)

Hardly surprising!

Doubling I^2 should halve the insulation life which may relate to the test duration. This can be confirmed or disproved if anybody does tests at other than 1 hour.

The discussion is absolutely nothing to do with the cable, its insulation or the life of that insulation - the only relevance of the cable size to the test is the rate at which it conducts heat away from the switch during the (1 hour) test.

Kind Regards, John

 

[Porque223]

Is there an icon for waving a white flag?

 

[EFLImpudence]