Blue/Neutral Wire

popecatapetal

I'm not *entirely* sure that this is the right place, but I can't see anywhere better so I'll ask here. How dangerous is an escaped blue wire in a plug? From what I know of it it's the live wire that's the one that's dangerous, but I could do with a second opinion just to be safe.

(Also, for clarity, I know that the appliance won't work. This isn't an issue, really. It's the safety.)

mathias

With alternating current you should treat both brown ( live ) and blue ( neutral) as the same when it comes to safety , indeed many appliances will work with these two swapped over ,
( Alternating current switches polarity at the mains frequency , here thats 50 times a second , so you can view it as each one pushing current every 50th of a second )

From a safety point of view , treat these as the same and never assume one is safer than the other ,

Of course all appliances should be wired up correctly , and earthed if its meant to be. You cant be too careful with electricity. And any escaped wire is dangerous and should be repaired asap.

DublinDilbert

popecatapetal wrote: »

I'm not *entirely* sure that this is the right place, but I can't see anywhere better so I'll ask here. How dangerous is an escaped blue wire in a plug? From what I know of it it's the live wire that's the one that's dangerous, but I could do with a second opinion just to be safe.

(Also, for clarity, I know that the appliance won't work. This isn't an issue, really. It's the safety.)

It can be quite dangerous depending on what it touches

If it touches the Earth terminal in the plug it will more than likely trip the RCD for the socket circuit. Will probably be a little sparking....

If it touches the Live terminal in the plug not much will happen.

If it touches the Neutral terminal, it will spark, depending on the size of the load it will spark more or less...

If it touches a person, they will probably get a shock, as current will flow via the appliance, once the blue wire becomes disconnected it will rise up to 220V.


Thats a long winded way of saying once its contained within the plug not much should happen...

Ummmm why u ask?

Timmaay

DublinDilbert wrote: »

If it touches the Live terminal in the plug not much will happen.

No, it'll short circuit and blow fuses/rcds if it touches the live (brown side) terminal.

To the OP, What do you mean by an escaped blue wire, has it been pulled out of the plug and is exposed? If so, it's dangerous if the plug is plugged in..

DublinDilbert

Timmaay wrote: »

No, it'll short circuit and blow fuses/rcds if it touches the live (brown side) terminal.

To the OP, What do you mean by an escaped blue wire, has it been pulled out of the plug and is exposed? If so, it's dangerous if the plug is plugged in..

I meant if the "blue" wire in the plug comes completely out of the neutral terminal in the plug, is floating around and touches the live terminal. Nothing will happen in this case, as both sides of the load are connected to the live!!!

mathias

I meant if the "blue" wire in the plug comes completely out of the neutral terminal in the plug, is floating around and touches the live terminal. Nothing will happen in this case, as both sides of the load are connected to the live!!!

Thats a dead short , ( they would both only be connected to the live terminal at the appliance , not the supply , the supply would see a dead short ) and depending on how its supplied will either trip a breaker or blow a fuse , the one time it happened to me , at work , there was a blue flash that left me blind for a few seconds , and gave me a hell of a fright too.

For the record , the mains lead , ( single phase 32A supply ) was cut with a metal box that was dropped on it. Its not the kind of thing that you let happen twice !

On a single phase AC supply live and neutral form the circuit , the earth typically carries no current and on most appliances is connected to chassis , the current supplied to the device arrives on the live and returns on the neutral ( but its alternating so that flips over every 50th of a second ) , an RCD measures whats going in and coming out which should always be the same , any difference and it should cut off the supply , an ELCB watches for current on the earth , and trips out the supply if any is detected.

To measure AC voltage , you measure between live and neutral , any attempt to measure between live/neutral and earth should trip a breaker or blow a fuse.

DublinDilbert

mathias wrote: »

Thats a dead short , ( they would both only be connected to the live terminal at the appliance , not the supply , the supply would see a dead short ) and depending on how its supplied will either trip a breaker or blow a fuse , the one time it happened to me , at work , there was a blue flash that left me blind for a few seconds , and gave me a hell of a fright too.

If i get a standard 13A 3 pin plug and wire an appliance to it, if i wire both the brown and blue wires from the appliance into the Live terminal in the plug, nothing would happen! This is not a dead short. The supply would not see anything! The supply wouldn't even know anything is connected...

mathias

If i get a standard 13A 3 pin plug and wire an appliance to it, if i wire both the brown and blue wires from the appliance into the Live terminal in the plug, nothing would happen! This is not a dead short. The supply would not see anything! The supply wouldn't even know anything is connected...

Im talking about the supply here , not the appliance , were looking at it from different ends ! Deliberately connecting live and neutral in the appliance plug will do nothing.
Having a wire floating around in the plug can easily result in a dead short , nothing connected to a socket should have a loose wire , especially not stranded wire , likewise with the socket , on the socket end its very important not to connect live and neutral or you get what I got , a nasty surprise.

Timmaay

DublinDilbert wrote: »

I meant if the "blue" wire in the plug comes completely out of the neutral terminal in the plug, is floating around and touches the live terminal. Nothing will happen in this case, as both sides of the load are connected to the live!!!

Sorry, I'm with ya now:o