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Old 20th Feb 2019, 4:44 pm   #1
avocollector
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Default Old Bulgin 3 pin mains socket/plugs

I've often wondered why these are no longer about. I seem to recall them being used in the 60's PW and PE designs and they seem to be the precursor of the modern 3 pin plug/socket mains leads you find that plug into the back of equipment. Was there some flaw in the original design that made them obsolete or was it just progress/modern materials?
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Old 20th Feb 2019, 5:08 pm   #2
kalee20
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Default Re: Old bulgin 3 pin mains socket/plugs

They were good, and I mourn their demise, but they couldn't be used above 50V according to modern safety regulations.

The line socket didn't have the contacts recessed far enough - they would easily accept a young child's finger. And the cover just unscrewed (no need to use a tool such as a screwdriver), exposing live contacts.

Either of these would force use to be restricted to SELV circuitry.
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Old 20th Feb 2019, 6:01 pm   #3
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Default Re: Old bulgin 3 pin mains socket/plugs

I fear the main reason that they are no longer about is that Jim Marshall ('the father of loud') chose them for his guitar amps and some of the people that used them didn't, shall we say, take very good care of them. The trailing sockets in particular got broken, on stage and in the backs of touring vans. But no-one wanted to cut their original amp about, so demand for the sockets now exceeds supply. If you want to buy one 'off the shelf' on eBay you could be looking at paying £25 per socket.

EDIT: Just to be clear, they come in at least three different sizes and two different pin geometries. The popular ones are the middle-sized version with the pins in an equilateral triangle.

Cheers,

GJ
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Old 20th Feb 2019, 6:26 pm   #4
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Default Re: Old bulgin 3 pin mains socket/plugs

I've just fitted the miniature version to a mains cable to power up a piece of Marconi Instruments testgear. Would I be right thinking the RH socket is Live?

I'd much sooner have modern EEC connectors, for robust safety and so you can find one in every room in the house. The thing I really don't like about the Bulgins is that they only take a very thin mains cable which you can't get now. Fortunately I found a reel of the stuff, also useful for the fixed mains lead on some older testgear.
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Old 20th Feb 2019, 7:04 pm   #5
Lucien Nunes
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Default Re: Old bulgin 3 pin mains socket/plugs

Someone please correct me if wrong, but I think the convention on these, like the larger types, is the reverse of the 'standard' configuration common to BS1363, IEC 60309, IEC 60320 etc. Looking into the female contacts with earth at the top, line is on the left and neutral on the right.
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Old 20th Feb 2019, 7:12 pm   #6
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Smile Re: Old bulgin 3 pin mains socket/plugs

Hi,
Just for interest, the power station I used to work at had six pin versions of the Bulgin connector. They were used for plugging test instruments into the turbo-alternator control system.
They were chipped & cracked too!
I think there was an eight pin version as well.
Cheers, Pete.
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Old 20th Feb 2019, 7:12 pm   #7
TonyDuell
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Default Re: Old bulgin 3 pin mains socket/plugs

The 'minature' one, as used for example on the Quad 33 and 303 is still made and available from RS. Here is a line socket that cannot be dismantled without a screwdriver.

https://uk.rs-online.com/web/p/compa...ctors/0489504/

I thought that one was OK for use on mains but RS say otherwise.

And they still do a similar-sized 6 pin chassis plug and line socket, for example

https://uk.rs-online.com/web/p/compa...ctors/2615799/

Last edited by TonyDuell; 20th Feb 2019 at 7:14 pm. Reason: Added a reference for the 6 pin version
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Old 20th Feb 2019, 7:26 pm   #8
Julesomega
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Default Re: Old bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by TonyDuell View Post
The 'minature' one, as used for example on the Quad 33 and 303 is still made and available from RS. Here is a line socket that cannot be dismantled without a screwdriver.
That one looks as though it takes modern compliant cable
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Old 20th Feb 2019, 7:44 pm   #9
Paul JD
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Default Re: Old bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by Julesomega View Post
I'd much sooner have modern EEC connectors
I think you mean IEC connectors - nothing to do with the EEC
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Old 20th Feb 2019, 8:41 pm   #10
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Default Re: Old bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by TonyDuell View Post
The 'minature' one, as used for example on the Quad 33 and 303 is still made and available from RS. Here is a line socket that cannot be dismantled without a screwdriver.

https://uk.rs-online.com/web/p/compa...ctors/0489504/

I thought that one was OK for use on mains but RS say otherwise.

And they still do a similar-sized 6 pin chassis plug and line socket, for example

https://uk.rs-online.com/web/p/compa...ctors/2615799/
They USED to be considered suitable for general purpose low power mains voltage connections, but standards have changed and they are now only considered suitable for mains IF WITHIN EQUIPMENT and only accessible to skilled persons, for example to replace a sub-assembly within a large machine.
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Old 21st Feb 2019, 12:49 am   #11
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Default Re: Old Bulgin 3 pin mains socket/plugs

They weren't very safe. The plastic shells were very brittle and easily cracked, and the cable grip method used on the straight-entry type was unreliable. The screw-on covers worked loose very easily.

I once got an extremely nasty shock from a WEM amplifier as a result of one of them falling to bits. Mid 1970's, and I still remember it!

Bulgin made several versions of connector in this general style, 8 pages in my catalogue, which I think dates from 1967.
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Old 21st Feb 2019, 4:03 am   #12
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Default Re: Old Bulgin 3 pin mains socket/plugs

Wiring details for L/N/E in Bulgin plugs/sockets - https://www.plugsocketmuseum.nl/Bulgin1.html
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Old 21st Feb 2019, 6:15 am   #13
TonyDuell
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Default Re: Old bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by broadgage View Post
They USED to be considered suitable for general purpose low power mains voltage connections, but standards have changed and they are now only considered suitable for mains IF WITHIN EQUIPMENT and only accessible to skilled persons, for example to replace a sub-assembly within a large machine.
I understood that was the case for the original type with the screw-on cap that could be removed without the use of a tool. But I thought the later type (as I gave the RS stock number for) and the right-angled socket, which have proper cable clamps (a strip and 2 screws) and cannot be taken apart exposing live terminals without using a screwdriver were OK for mains. Perhaps the regulations have changed again.

Personally I don't use them except for compatibility, and I use the new-type of socket assembled with screws (as above). As I am the only person to have access to them (nobody else in the house) I am not too worried.
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Old 21st Feb 2019, 9:20 am   #14
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Default Re: Old bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by Julesomega View Post
I've just fitted the miniature version to a mains cable to power up a piece of Marconi Instruments test gear. Would I be right thinking the RH socket is Live? ...
Yes that is correct for the 1.5 Amp connector when looking at the face (all of the equipment I have / had is wired that way). You will likely find the L, N and E embossed on the inside of the plug and socket if you look.

Take Care, unfortunately there are errors in the Plug and Socket Museum's pictures.
Picture 9 is wrong, L and N are the other way round. Picture 10 shows the correct wiring for the chassis mounted 'socket', not the 'plug'.
And the 5 Amp plug in picture 2 is wrong, the L and N are reversed again if looking at the plug face. (It is actually the layout for the chassis 'socket in picture 1.)
Again lots of them have L, N and E embossed on them, so follow that...

Alan
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Old 21st Feb 2019, 12:56 pm   #15
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Default Re: Old Bulgin 3 pin mains socket/plugs

I wondered about those wiring connections - we were taught the mantra "Red is Right", meaning right pin was L when looking at the pins on a plug.

That, quite obviously, was before the colour change.
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Old 21st Feb 2019, 12:59 pm   #16
GrimJosef
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Default Re: Old Bulgin 3 pin mains socket/plugs

I was also taught "Red is Right", meaning right pin was L when looking at the (BS1363) socket. Stating the obvious, it reverses depending on which side of the plug or socket you're looking from. 99% of people will be looking at the 'front' of the assembled unit. The 1% who are actually wiring it up will be looking at the 'back'.

Cheers,

GJ
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Old 21st Feb 2019, 1:33 pm   #17
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Default Re: Old Bulgin 3 pin mains socket/plugs

I like those miniature Bulgin three pin connectors and in my opinion they are perfectly satisfactory for low current 230V mains use. If fact I liked them so much (as I did the TV show Blake's 7) I built a miniature TV in its honor called Orac (after Orac on Blake's 7) and used one of these connectors as the mains input...here it is:

http://worldphaco.com/uploads/ORAC.pdf
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Old 21st Feb 2019, 2:50 pm   #18
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Default Re: Old Bulgin 3 pin mains socket/plugs

Quote:
Originally Posted by GrimJosef View Post
I was also taught "Red is Right", meaning right pin was L when looking at the (BS1363) socket. Stating the obvious, it reverses depending on which side of the plug or socket you're looking from. 99% of people will be looking at the 'front' of the assembled unit. The 1% who are actually wiring it up will be looking at the 'back'.
If you are facing AWAY from the dynamo, the LEADS are on the LEFT, and the RETURNS are on the RIGHT.
The BULGIN connectors are, in fact, the 'wrong way round'.
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Old 21st Feb 2019, 3:54 pm   #19
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Default Re: Old Bulgin 3 pin mains socket/plugs

Looking into a Bulgin 3 pin chassis mounted plug (ie: 3 male pins) from the customers side with the location notch at the bottom the Live pin is on the right and the Neutral pin is on the left in a photo of the one I'm looking at.

Lawrence.
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Old 21st Feb 2019, 3:59 pm   #20
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Default Re: Old Bulgin 3 pin mains socket/plugs

Does it matter? Both line and neutral are considered live conductors and it has a ground too.
 
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