Noob Question on 63amp single phase plug

[Andy McNeil]

Hi All,

I'm not an electrican, i work in the events industry and we have quite a bit of plug and play distribution. I have just recieved a 63amp single phase (blue C form) plug on the end of a cable and was surprised to see it had the usual three pins but now a forth smaller pin shortert han the rest.

I googled it and it seems to suggest this is a refernce pin and it is used to check there is a good earth befroe current can flow. Is this right. if anyone could explain what this mystery forth pin is and how it works i would be really grateful.

Thanks Andy

 

[Boing89]

It’s part of a pilot system that ensures your equipment earth wire is okay. If your equipment doesn’t have a pilot system (and not all does) it can be shorted out so the system still works. My advice is to leave this to an electrician who understands if it’s safe or not. Sometimes it will be and other times it won’t.

It works by passing a small current down the earth wire, through the equipment and back down the pilot wire. If the system breaks down anywhere your distribution equipment will sense it and not allow power to be applied.

 

[Deleted member 26818]

As far as I am aware, it’s just a pilot pin which switches on and off the supply.
Used on 63A and 125A only.

 

[Andy McNeil]

Thank you so much, thats very helpful. Rest assured i would never tamper with something like this. Thanks again for your time to explain its good to know

 

[Boing89]

As far as I am aware, it’s just a pilot pin which switches on and off the supply.
Used on 63A and 125A only.

I’ve seen it all the way down to 16A plugs in the past. Usually for use in special areas such as ATEX zones. In that situation it works by tripping out the power when the pilot circuit is broken preventing arcing if the plug is pulled from the socket while under load.

 

[Deleted member 26818]

Think it’s called a Pilot Contact Switch.
The pilot pushes a switch on a mechanical contactor which then connects the live pins.

 

[buzzlightyear]

is this a second post from the op .

 

[Boing89]

Think it’s called a Pilot Contact Switch.
The pilot pushes a switch on a mechanical contactor which then connects the live pins.

I’ve only seen a mechanical version once. A lot of the time it used to be a relay (although electronics is taking over). If your pilot circuit was made then the relay energised closing a main contactor, if it was broken then everything de-energised.

 

[Deleted member 26818]

is this a second post from the op .

Don’t know?

 

[westward10]

is this a second post from the op .

Other one is a different subject.

 

[buzzlightyear]

I must be me then looking two posts the same time and did not realise.