Mystery Device - Double Socket Bayonet Adaptor

A small bayonet adaptor (BA15d) with two sockets. There is no provision for connecting any wiring.
Includes a small bayonet plug, and although wiring could be connected to that, this is wrong, as it would result in a plug with live exposed contacts.
Even if that was correct, all that is achieved by use of both items is a small bayonet holder on the end of a cable - far simpler and easier to just use a single holder with a flex grip fitted.
Website: xo4.uk/?sBC

[@ed.drinkwater3815]

This is a vintage vehicle lamp bulb holder. This would be mounted through the shell of the lamp, and the power connected to the bayonet plug so the lamp can be removed from the vehicle for maintenance or safe keeping. The exposed live pins are not really dangerous when the supply is a 12 or 24 volt battery. These are still readily available from vintage vehicle parts suppliers.

[@johnhampson7]

Hi John, I'm a pensioner now but I recall using an extension coupling just like this when I was a young lad. We had electricity in our house when I was small, but only for light. No sockets, they came later when we could afford them. My mum used to connect her iron into this little connector and then connect another length of cable with two little bacolight plugs, one at either end, then she would simply take out the bulb and connect her iron. Our Christmas lights were also connected using the same coupling.

[@kokotas67]

my guess (if this is a vintage item): when electricity was first introduced at homes the first and only for quite sometime use was powering light bulbs. when other electrical appliances were first introduced the only readily available socket for electricity was that of a lamp socket. so the cable at the end of the appliance would have the same plug as a bayonet lamp, and it would be attached directly to a lamp socket in order to power the device. so this item looks like a coupler probably to add more cable lengths. that might explain the plug featured in this video.

[@hellcattanks]

I have seen something like this before, a low voltage lamp for use in aircraft, the bulb and reflector/shade are all one in conjunction with this item, the assembly is plugged in and you have a instant maplight, and when not required can be unplugged and put out of the way.

[@ElectricalMuseum]

I suspect it was intended for signal connections rather than electrical power. Various power connectors (including for example 5A 2-pin and Wylex Polarised as well as bayonet) have also been used for audio, measurement and other diverse functions. I have a photometer made by reputable manufacturer with a B22 connector for the selenium cell that could esily be plugged into a lighting point - not very foolproof but it was not intended to be used by fools! Usage for a signal application would perhaps explain the metal-bodied construction of the adaptor as well as the back-to-back connector. The latter might have been used for joining two standard cables fitted each with a plug at both ends, a configuration that is still standard for many signal applications such as coaxial video and loudspeakers.

[@techy4198]

I would personally say this was some solution to lamp shade struggles. Have the plug on a flex from the ceiling, use the adapter to put the bulb inside the shade before actually connecting it to the flex. This would help when the shade is a large or heavy decorative piece. The exposed connections would supposedly be safe as long as the fixture was switched off (I assume most people are smart enough to do so when changing bulbs anyway), also assuming power to the fixture was not incorrectly switched on the neutral side.

[@techy4198]

Source: my bedroom lamp shade is enormous and took both me and another person, me on my bed and her on a fairly high chair, to get the shade screwed on and the bulb inserted properly - someone could have invented this in a similar situation.

[@Slikx666]

Probably for use to join 2 leads together when using a light fitting as a power supply, I think they used to do this in the 1940's as I've seen it done for ironing clothes... If the lead wasn't long enough then 2 or more were needed.

[@lucapadovani7396]

I've seen a sort of "plug" which fits into a bayonet lamp holder. This may be so that a lamp could be powered by a piece of flex connected to the mains and having a bayonet male fitting on the end.

[@KevinOsborne1987]

Did you ever find out what this was?

[@God-CDXX]

I have old tube amps with these on the mike cables

[@be.spiritlove]

I have a idea what it might be for, old fluro tubes had BC connections on both ends, would it be to connect two tubes together?

[@jwflame]

Justin Coleman Fluorescent tubes had the larger size B22 bayonet connectors, this is a smaller B15 size.

[@imark7777777]

I would say much like some of the other comments this is used for a signaling application, with audio, test equipment or a low voltage lighting system. my suspicions would be a combination of all 4 and maybe on an antenna transmission cable interconnect. very interesting. and something you would be shot for if you made today in an developed country (NEC/ OSHA / Other Codes ) and you tried to sell it and it fit something in the 100-400V range.

[@farerse]

how did you get that shirt? were you a fan of that show?

[@davidchamberlain2162]

It smells of DC low voltage to me. I have worked at remote transmitter sites that had a generator room for back-up power. If the generator did not start there was a 12 volt light switch that connected a bulb via the starter battery so you could see what you were doing. The bulbs looked the same as 240v ones. Could this be off an aircraft or a ship. Not sure quite what it is for though. Ask BigClive he has worked on all sorts of lighting systems.

[@FredBedderhead]

it look like it for joining old microphones and audio cable together, I had a really old microphone and tube amp with connection that look like that for the outputs and inputs

[@PeakyBlinder]

up in my loft i have a bayonet plug with 2 wires coming out, the other end of the two wires connects to a light bulb, to give power to the bulb i have to remove a bulb from the upstairs light and insert the bayonet plug into the where the light-bulb would go, this then gives power to the bulb in the loft. what you have there you would put a bulb in one end and use a bayonet power supply to fit in the rear to give power to the bulb. a kind of quick release power supply or a temporary power supply to a light bulb.

[@PeakyBlinder]

+kempouk ps you would need either a wall plug to bayonet connector (extension lead) or a bayonet to baronet (extension lead ) to give power from a light bulb socket, it is like a quick release power supply if you will, ie an extension from 1 bulb socket to another.

[@edwardcat5247]

yes... we all make the modern immediate assumption it is 240v... of course, if it is 12v or signal then many specialist uses come into play...

[@YouTube2021FM]

Might have figured it out - this would be very useful for quick changes for theatre. It would allow you to quickly swap a lamp AND lampshade during a scene in a matter of seconds, without having to unscrew anything. Still not the safest thing in the world, but would definitely solve a niche problem! May be slightly less dangerous due to operator control in theatre.

[@projectwes4573]

That unit was designed specifically to hold a specialty shade that runs a lamp on low voltage DC current

[@cremationpete]

It is from a test unit. Not designed for powering a lamp.

[@jwflame]

cremationpete That certainly seems far more likely than a lamp.

[@PC-841]

Simples wireless lighting, it's the future.