Worst connector ever invented

[littlespark]

I suppose the old cigarette lighter is exactly the same problems as a B22 bayonet lampholder.... just less voltage.

 

[DPG]

I suppose the old cigarette lighter is exactly the same problems as a B22 bayonet lampholder.... just less voltage.

And no bayonet locking system. So the plugs just work their way loose over time

 

[mainline]

And no bayonet locking system. So the plugs just work their way loose over time

They worked well as a cigarette lighter, which is what it was meant for.

 

[DPG]

They worked well as a cigarette lighter, which is what it was meant for.

Absolutely. Fancy them not having the foresight to realise we may need to use them to charge up a telephone which works without wires!

 

[davesparks]

If anybody cares to listen to my rants about the fiddly ones I will happily rant.

Does EDAC make the list by any chance?

 

[littlespark]

Who edited my post #16?

I used the word F. A. G and it changed it to “smoke”

 

[Lucien Nunes]

Let's talk about the 'stage pin' connector used in the USA. There is a general advantage in the entertainment lighting to a connector that lies flat on the floor when mated with a trailing socket. In the tungsten lighting era it was also customary for lighting to use a different plug that could not be interchanged with the local standard mains plug, so that things that should not be dimmed couldn't accidentally be plugged into dimmers. Therefore various lighting-specific connectors evolved that were sometimes (although not always) flat. In Britain we had the 3-in-line followed by the Healee, both now obsolete, and in the USA there was something similar to the 3-in-line that is still in use today, called the stage pin, available in 20, 30, 60 and 100A versions.

Stage pin plug and socket have flat bodies that mate end-to-end like dominoes. The higher current types especially are big and heavy, with stumpy brass pins. All pins are the same diameter and lie in a straight line, but the ground pin is longer to ensure it mates first. The huge mistake in the design is that although they are polarised by having the middle pin offset, they can be mated wrong way round with one or two pins engaged but the third one exposed. The pin positions of the 20A type are different to the others, with the ground in the middle instead of at one end, which makes it even easier to mate the plug flipped and offset so that the ground pin goes into the line socket, making the equipment casing live. Other permutations are possible with exposed pins becoming live or whatever. This problem didn't exist with British 3-in-line type because not only did it have a flange around the socket to prevent offset positioning, the earth pin was of larger diameter and would not enter the line or neutral sockets.

There are other issues with stage pin. Some types rely on the pin halves being sprung apart to get secure contact, but the pins are completely exposed and the larger plugs very heavy. If you drop them they tend to land pin-first, squashing the two halves of the pin together, requiring them to be splayed apart again. There is a special tool for this called a pin splitter, with a T-shaped handle attached to a tube with a wedge inside, that you press over the plug pins in turn to spread them open. The socket contacts are often very close to the mating face of the socket, so you can touch them. The larger sizes a small finger can enter. If not mated completely snug there is an obvious gap around the pins that can allow conductive objects, even fingers, to touch the live pins, being very near the edges.

I don't have any pics of these to hand and I don't want to link to any sellers given that I am rubbishing the design generally. But if you Google 'stage pin plug' there are plenty of examples to look at. I've only ever specified them in a couple of places in new systems; generally we were using twist-locks for lighting to separate them from hard mains on straight blades.

Just realised that I've been inconsistent in terminology with earth vs. ground and line vs. hot. Can you live with line and ground? The film industry is a transatlantic thing anyway, we often end up with half and half. I'm used to wiring brown and blue to a 5-15 and black and white to a BS1363.

 

[YossiD]

Is your connector similar to these?

I am in Israel, and these are the standard for connections in light fixtures, junction boxes, etc. They come in half a dozen sizes to accommodate various wire gages and numbers of wires.

The bodies are some kind of plastic, and for high temperature applications they are also available with ceramic bodies.

I have never heard about any safety issues with these unless the screws aren't properly tightened. As they age, the screws sometimes corrode, making them difficult to open for service, but other than that they are generally reliable.

Am I the only one who loathes these connectors and just removes them immediately

Apparently they also turn a class 1 light fitting into a class 2 light fitting, this is surely not compliant unless you only have a single cable supplying the light fitting, so then the connector can completely enclose any single insulated piece of conductor

which is usually not the case

a loop in scenario at the ceiling and you have no chance, I have come across lots of these lately and have just been crimping a lug to the earths and screwing them to the mounting plate

not ideal but what else can you do with them?View attachment 106437

 

[DPG]

Is your connector similar to these?
View attachment 106489

I am in Israel, and these are the standard for connections in light fixtures, junction boxes, etc. They come in half a dozen sizes to accommodate various wire gages and numbers of wires.

The bodies are some kind of plastic, and for high temperature applications they are also available with ceramic bodies.

I have never heard about any safety issues with these unless the screws aren't properly tightened. As they age, the screws sometimes corrode, making them difficult to open for service, but other than that they are generally reliable.

Yes, we use those types also. Absolutely fine in the right circumstances. We do have to ensure they are not hidden though, as they need to be checked for tightness periodically.

 

[Lucien Nunes]

Yes the same type of terminal block is standard in the UK. The problem with the assembly that the OP mentioned was that it's not suitable for the types of cable that you would expect to use in these fittings.

 

[YossiD]

In the US, where I grew up, we used to use wirenuts, which worked quite well if properlry sized and tightened.

Here in Israel they are virtually unknown, and one electrician who did know about them told me they're not permitted by the local codes. Do you guys use them?

Yes, we use those types also. Absolutely fine in the right circumstances. We do have to ensure they are not hidden though, as they need to be checked for tightness periodically.

 

[Lucien Nunes]

Not for many decades. We used to have a ceramic version often known by the brand name 'Scruit' although there were other brands. They can sometimes be found in very old wiring.