Lampholder Overcurrent Protective Device.

[333rocky333]

Could it have been due to the current fad at the time, of using adapters in the lampholders to power appliances

 

[JohnW2]

Could it have been due to the current fad at the time, of using adapters in the lampholders to power appliances

Who knows? I certainly remember that 'fad' period - particularly my grandmother with her iron plugged into such an adapter.

However I doubt that would have been the explanation. It might have been had the 'limit' been 5A, rather than 15A, but I suspect that the 15A limit would not really have had much effect, since 'appliances' would (at least 'one at a time'!) have been appreciably less than 15A.

Kind Regards, John

 

[Swwils]

For 13A BS1362, I2 is 26A.

Uh oh! 433.1.1!

 

[JohnW2]

For 13A BS1362, I2 is 26A. ... Uh oh! 433.1.1!

Indeed -and we've discussed that before.

The relevant part of 433.1.1 is obviously only applicable to fuses ...

(ii) the rated current or current setting of the protective device (In) does not exceed the lowest of the currentcarrying
capacities (Iz) of any of the conductors of the circuit, and
(iii) the current (I2) causing effective operation of the protective device does not exceed 1.45 times the lowest of
the current-carrying capacities (Iz) of any of the conductors of the circuit.

.... since (iii) is redundant for an MCB which compliant with it's product Standard. Since such a Standard requires that (I2 ≤1.45 x In), any (product Standard compliant) MCB which satisfies (ii) would also satisfy (iii).

However, as for BS1363 fuses, as I've pointed out before, this means that the cable used for a '13A fused spur' should have a CCC and installation method which results in a CCC of at least about 18A (26A /1.45). That means that (contrary to what some people might think is implied by Appendix 15) 1.5mm² T+E is, strictly speaking, seemingly not adequate with anything other than installation Method C, and nor seemingly is 2.5mm² T+E adequate if installed with Methods 101 or 103

Kind Regards, John

 

[Swwils]

I always thought that 559.5.1.204 was because of the size of the terminals inside of those types of light fittings.

 

[JohnW2]

I always thought that 559.5.1.204 was because of the size of the terminals inside of those types of light fittings.

That's obviously a potential practical issue, but I don't really see that, even if they wanted to, imposing a limit on the In of the OPD would be the way to address it. After all, the reg does not stop someone trying to use 10mm² cable in a lighting circuit, so long as the In of the OPD is not above 16A!

I see no corresponding reg attempting to discourage people from using 16mm² T+E for sockets circuits

Kind Regards, John