Table Lamp Sockets

[ericmark]

Because B22 lampholders are only rated to 2A

559.6.1.6 Lighting circuits incorporating B15. B22. E14. E27 or E40 lampholders shall be protected by an overcurrent protective device of maximum rating 16A.

But you are right just got one and checked and it is rated 2A. Bulbs however are supposed to have built in fuses so when they blow and have ionization the internal fuse will blow rather than main one.

However I have found this is not the case with all compact fluorescent units and I have had an Ikea one weld itself onto the contacts so maybe in the future we will need to change our 6A MCB's go 2A?

 

[Lectrician]

Lamps have not had fuses in the base for some time. It is very common to see MCB's tripping and even the odd fuse blowing when a lamp fails these days. Downrating to a 2amp fuse or MCB would just make this worse.

 

[ericmark]

Since the fuse in the bulb was not renewable and just a thin wire used in construction of the bulb and not visible the only way to be sure it does not exist would be to test it by breaking the bulb and running current through it. I was an integral part.
Until your post I was unaware of the 2A rating of the bulb holder I do remember in the past before we used 13A sockets the lighting supply was used quite often to power items like smoothing irons. I remember the adaptors one had to convert B22d into 5A 2pin. And with only a couple of sockets in the house before we started using ring mains we did use the lighting supply a lot.
I think it was illegal as the lighting was supplied from different meter than power on two different tariffs. but I was only born in 1951 and I would have only seen this in my granddads house. (Dads house 1954 and had new fangled 13A sockets and ring main) Likely only about 6 at the time. I remember he had loads of rewireable fuses which had a clip arrangement and spare wire wrapped around the back of each fuse. Each socket would have had its own fuse.
I had there for expected the lamp holders to have originally been rated at 5A.
Also I have bought festoons of lamp holders with around 25 lamps at around 3 meter spacing E27 holders moulded onto cable complete with 16A plug attached so I had assumed they were rated at 16A as 25 x 60W lamps = 13.63A even with 40W it is 9.1A and 25W still 5.7A so nearly impossible to have got the total load under 2A. I am of course using 110V on these lights.
Out of interest I will do some research as I wonder why the BS7671 allows us to use up to a 16A protective devise. I will try to hunt out some old B22d lamp holders and see if they have different rating.

 

[Spark123]

What's the maximum wattage lamp you can put in a 2A lamp holder?

 

[ericmark]

The largest I have seen are 150W although no longer made I believe. One can still get 70W and these are bright but not sure as to max amps as there will be some inrush with a metal halide lamp so not as simple as ohms law.
But I would think for no fault conditions about 1A. However under fault conditions or where wrong type of bulb is used it can exceed the 2A without a problem. My wife managed to blow a 13A fuse when she hunted in my garage for a E27 lamp and fitted in error a Son 70W lamp in a E27 lamp holder with no started gear connected.
Then got upset when my son laughed at her when it went bang.
So the answer must be less than 160A as it did not trip B32 MCB but greater than 13A as it did blow fuse.
Anyway greater than rated 2A.

 

[RF Lighting]

Yeah but it doesn't work like that.

The lampholder is designed to supply a maximum load of 2A. Of course this could be exceeded if it is used outside of its design parameters, and during fault conditions, but then, exactly the same could be said of a 13A BS1362 socket outlet.

We dont go around fitting 125A sockets to cater for fault currents.

 

[ericmark]

Yeah but it doesn't work like that.

The lampholder is designed to supply a maximum load of 2A. Of course this could be exceeded if it is used outside of its design parameters, and during fault conditions, but then, exactly the same could be said of a 13A BS1362 socket outlet.

We dont go around fitting 125A sockets to cater for fault currents.

So considering same difference between 2A and 6A then if we draw 39A through a 13A plug you feel the fuse should not blow!

What we must remember the same BA22d socket could have a 24v hand lamp bulb or a 230v household bulb and 48w is not much and I have used 60w hand lamp bulbs which would be 2.5A which is overloaded without any fault. In fact I have one over my grinder now.

 

[ericmark]

What's the maximum wattage lamp you can put in a 2A lamp holder?

At 12v 24W, at 24v 48W, at 110v 220W and remember the same holder is used for many voltages.

 

[securespark]

Lamps have not had fuses in the base for some time.

I beg to differ!

Some do, some don't.

Cheap lamps generally don't, branded quality lamps generally do.

 

[RF Lighting]

So considering same difference between 2A and 6A then if we draw 39A through a 13A plug you feel the fuse should not blow!

In the real world, a 13A socket on a standard ring circuit drawing 39A is unlikely to ever blow a 30A BS3036 fuse, and would take about 16 hours to operate a BSEN60898 MCB

 

[securespark]

Mmm, I suspect the socket would show a lot more distress a lot sooner than the CPD....

 

[ericmark]

So considering same difference between 2A and 6A then if we draw 39A through a 13A plug you feel the fuse should not blow!

In the real world, a 13A socket on a standard ring circuit drawing 39A is unlikely to ever blow a 30A BS3036 fuse, and would take about 16 hours to operate a BSEN60898 MCB

But there is a 13A fuse in the plug! To draw 39A from a 13A socket protected only by the 30/32A protective device one would need to by pass the 13A fuse in the plug which is a whole different ball game.

 

[securespark]

How much overload can a 13A 1362 take?

When I went to the Royal Armoury in Leeds, their loos had pairs of Warner Howard hand dryers fed from one 13A switched spur. From memory, they're 10A each.

 

[333rocky333]

some hand dryers are less than 7 amp now.

 

[securespark]

I am prepared to accept that.

But these weren't 7A dryers. They were standard WH dryers and the last time I looked (int' bogs at Morrisons ) they were 10A apiece.