Plug advice / help

[Nelly111s]

Hi,
I have an old 110V transformer and need a plug to fit it. I'm not sure what this type of plug is called (i.e. what to search for on eBay etc.). It looks like the "lower" two pins have flats on the inside. Has anyone any clues as to what I'm looking for?

Thanks

 

[guineafowl21]

Not sure on the plug, might be easier to fit a modern socket. The thought occurs that 300VA intermittent won’t be a great deal of use, and you’ll need to find some suitable fuses.

 

[Nelly111s]

Not sure on the plug, might be easier to fit a modern socket. The thought occurs that 300VA intermittent won’t be a great deal of use, and you’ll need to find some suitable fuses.

Do you mean "fit a modern socket" into the transformer? Not sure of clearance etc. inside the transformer.

I suspect the transformer will still work and it may still power the hedge cutter it came with

 

[guineafowl21]

Yes, or blank and disconnect the old socket internally and run the hedge cutter flex straight into the box through a gland . You‘d really need an isolation switch in that case.

Or, blank as above and fit a modern socket on a tail.

Any pics of the hedge cutter? Must be a proper vintage piece.

 

[Spectric]

I have an old 110V transformer and need a plug to fit it. I'm not sure what this type of plug is called (i.e. what to search for on eBay etc.). It looks like the "lower" two pins have flats on the inside. Has anyone any clues as to what I'm looking for?

It is called obsolete, must be pre 1960 so why not just buy a new transformer that allows you to use the modern plugs ?

 

[ChaiLatte]

Look through what they catalogue here to help identify it:

https://www.plugsocketmuseum.nl/

 

[alan895]

A Google search of 'Tarpen transformer' brings up a similar model (a 150A), and what I assume would be the original packaging box states "fitted with special Tarpen non-standard outlet socket".

 

[XTiffy]

It is quite possible to buy a surface mount 110 volt socket and change your plug on the lead to match. Look in Screwfix and others. Just google 110 volt Socket/Plug.

 

[Nelly111s]

It is called obsolete, must be pre 1960 so why not just buy a new transformer that allows you to use the modern plugs ?

I think if I was going to the trouble of buying a new transformer, i'd go "the whole hog" and buy a new hedge cuter. I'm just trying to use old stuff that works in this case, rather than wasting some more of the earth's resources.
But I may end up with a new hedge cutter ...

 

[Spectric]

That old hedge cutter has already outlived many and is probably made from cast alloy and not plastic and well built so probably has many years left in it.

 

[trvlr]

The socket seems to resemble the 3pin 15amp (and 5amp) round in sockets used pre 13amp plugs... Is one pin larger than the other two - which it ought to be - as that pin will be the earth/ground connection for the load and also acts as a locater (ensuring that live and neutral are connected correctly to the load...). In the days of round pin plugs it was often possible to have two pin plug which fitted into a 3 pin socket and have the live and neurtal inadvertently switched... On a basic isolating transformer - 240 in 240 out - not a step down transformer - there may not always be an actual earth for the load...; volts out being truly isolated from the input side but no earth for the load via the larger third pin. Other versions did/do have an actual earth connection via the third pin and it gets that from the input side of the transformer. Much as today most, if not all, site transformers have an isolated o/p and the third pin is an earth connection via the input.

Bearing in mind the apparent age of the transformer I'm inclined to feel it's a standard 3pin 5amp socket requiring (the then) standard 5amp three pin plug; preferably rubber or similar.

So what you likely have is a 240volts in 110volts out (step down) isolating transformer - hopefully with an earth...

Today such transformers have shielded/skirted sockets and plugs of course with a locate in the skirt/shield, but still with that third larger pin..

You might try online for a 15amp or 5amp - whichever size (I suspect it's the 5amp) - three pin plug and see if it will fit; something like this:

https://www.amazon.co.uk/MASTERPLUG-Black-Round-Mains-Plug/dp/B07MK4M2WW
https://www.amazon.co.uk/Round-Plugs-Mains-Lighting-Stage/dp/B08CRTPYQH?th=1
As for replacing the existing socket... on something of that apparent age I'd be cautious. It may not as easy as you think... and if you get it wrong...

- is an excellent explanation of isolating transformers; which is what you have. View it to the end as JW covers all the variants.

 

[Nelly111s]

The socket seems to resemble the 3pin 15amp (and 5amp) round in sockets used pre 13amp plugs... Is one pin larger than the other two - which it ought to be - as that pin will be the earth/ground connection for the load and also acts as a locater (ensuring that live and neutral are connected correctly to the load...). In the days of round pin plugs it was often possible to have two pin plug which fitted into a 3 pin socket and have the live and neurtal inadvertently switched... On a basic isolating transformer - 240 in 240 out - not a step down transformer - there may not always be an actual earth for the load...; volts out being truly isolated from the input side but no earth for the load via the larger third pin. Other versions did/do have an actual earth connection via the third pin and it gets that from the input side of the transformer. Much as today most, if not all, site transformers have an isolated o/p and the third pin is an earth connection via the input.

Bearing in mind the apparent age of the transformer I'm inclined to feel it's a standard 3pin 5amp socket requiring (the then) standard 5amp three pin plug; preferably rubber or similar.

So what you likely have is a 240volts in 110volts out (step down) isolating transformer - hopefully with an earth...

Today such transformers have shielded/skirted sockets and plugs of course with a locate in the skirt/shield, but still with that third larger pin..

You might try online for a 15amp or 5amp - whichever size (I suspect it's the 5amp) - three pin plug and see if it will fit; something like this:

https://www.amazon.co.uk/MASTERPLUG-Black-Round-Mains-Plug/dp/B07MK4M2WW
https://www.amazon.co.uk/Round-Plugs-Mains-Lighting-Stage/dp/B08CRTPYQH?th=1
As for replacing the existing socket... on something of that apparent age I'd be cautious. It may not as easy as you think... and if you get it wrong...

- is an excellent explanation of isolating transformers; which is what you have. View it to the end as JW covers all the variants.

No, all the pins appear to be the same diameter, with the lower two having flats on the inside, so that it is only possible to fit it in the socket one way.

 

[trvlr]

I can vaguely recall plugs of that type aeons ago; but no idea if they're still about; nor where to find them.

This a site/forum etc. below may be of help? They have a menu bar across the top where you may find some useful input if you decide to logon there?.

https://vhgmc.co.uk/photo-galleries/tarpen/tarpen-transformer-imgtarp033/
Have to say though I'm doubtful you'll find a plug anywhere, but no harm to try the above chaps? Tarpen (made all sorts of goodies) disappeared in '76 and is now part of the Science and other museums...