Another socket puzzle: Why the extra terminal?

[Lucien Nunes]

Here's an old accessory made to BS1363. You can connect it to a ring and plug 13A plugs into it. What is the fourth terminal for?

I've blanked off some text moulded into the bakelite so as not to give too many hints at first. Nothing else is hidden.

 

[Lucien Nunes]

Front. So what's the terminal for?

 

[SJD]

So maybe a fused output for something you wouldn't need to plug/unplug, but is hard wired in - e.g. a doorbell?

 

[Pete999]

Front. So what's the terminal for?

View attachment 47708

Fused supply for the 5 Amp sockets, get a grip.

 

[SJD]

Aah, I was thinking "fireside" socket but no idea why it would need an extra terminal, unless for something to be hard wired in.

 

[telectrix]

the 4th terminal is a fused L for 5A round pin socket/s.

 

[Lucien Nunes]

Fused supply for the 5 Amp sockets, get a grip

They're 2A, and the fuse is built-in.

 

[Pete999]

the 4th terminal is a fused L for 5A round pin socket/s.

What I said except get a grip. Not you Tel

 

[Lucien Nunes]

Why would you want to cater for 2A sockets when installing a ring?

 

[Pete999]

the 4th terminal is a fused L for 5A round pin socket/s.

Still not many 5 Week wonder DI courses have seen this sort of thing have they?

 

[SJD]

The valve radio, or the table lamp.

 

[Pete999]

The valve radio, or the table lamp.

What is that supposed to signify SJD?

 

[Toneyz]

The terminal is not shrouded like the rest. It appeared to be the size of a single socket in the first picture.

 

[SJD]

My comment was in reply to Lucien's question just above as to what you would use the 2A sockets for!

 

[Pete999]

Table or standard lamps as was the norm in those days, 50s 60s 70s maybe long before people decided to change careers

 

[Lucien Nunes]

The fourth terminal is indeed an output sharing the onboard fuse protecting the 2A sockets. It's intended for the rarely-seen companion unit containing a further four 2A sockets. The combination appears on the ring as one double point (one 13A socket and one unswitched FCU) but gives a total of seven sockets in two accessories. Heater, clock, lamp, TV, radiogram, other lamp, train set, spare, or whatever.

Never caught on, presumably as it defeated the idea of all plugs being identical and hence interchangeable.