Over heating on the netural?

[r.bartlett]

Guy's

One of our engineers has been looking at a dairy deck fridge at a customers coffee shop. Three times he has been down and thre times the netural has overheated. Twice in the plug and once in a cable extender. I believe it is 2.5mm flex and a length of 3m.

I don't know amps as I haven't spoken to him and as he went there yesterday morning and I just got a message it's gone down again

 

[Iggifer]

loose connection somewhere?

I had a 16a socket outlet & plug weld the neutrals together because the plug wasn't fully pushed home

When I say welded, I mean welded, nobody could get the plug out of the socket, it was a good 'if you can get this plug out I'll give you £50'

sword in the stone and all that

 

[RF Lighting]

 

[bernardgreen]

When repairing this type of over heating fault it is vital to cut back to copper that has not been softened by the heat at the faulty joint / connection / plug-socket. If the joint is re-made on the copper that was heated it will often fail again as the copper deforms under pressure from the screw.

If it is not possible to get to good copper a more reliable temporary repair joint can be made by putting a crimped boot lace ferral on the strands before making the joint until new cable can be installed.

 

[Iggifer]

Untitled

• Iggifer
• 10 Dec 2012
• 1

Shows how the far home the 'genius' has pushed the plug, hardly surprising there was some arcing going on, that's nearly a full cm out of the socket. I'm amazed it worked at all

 

[JohnW2]

Shows how the far home the 'genius' has pushed the plug, hardly surprising there was some arcing going on, that's nearly a full cm out of the socket. I'm amazed it worked at all

You say that, but I wouldn't mind betting that, even with that 1 cm gap, there was probably still a lot more contact between pins and 'receptacles' than there is with a BS1363 13A plug/socket.

Kind Regards, John

 

[r.bartlett]

we replaced the 13a plug on the double socket and wired it into a fuse spur and it lasted since Monday

We can't see anything wrong and it's getting silly...

Untitled

• r.bartlett
• 14 Dec 2012
• 1

going back to replace the 13a spur and also the cable..

 

[ricicle]

Unfortunately, in my experience, 13A plugs, sockets or FCUs do not like being ran constantly at or near 13A !
You need to look at the loading of this fridge and number of starts as it could be too great for any of the 13A connection points (plug, FCU etc)
One or other of the poles could burn out due to excess load but in this instance coincidentally it is always the neutral.

 

[JohnW2]

Unfortunately, in my experience, 13A plugs, sockets or FCUs do not like being ran constantly at or near 13A !... One or other of the poles could burn out due to excess load but in this instance coincidentally it is always the neutral.

Isn't it actually most commonly the vicinity of the L (pin/ receptacle/ terminals/ connections) that suffers thermal damage, the heat generation often originating from poor contact between fuse and 'holder'?

Kind Regards, John

 

[ricicle]

Unfortunately, in my experience, 13A plugs, sockets or FCUs do not like being ran constantly at or near 13A !... One or other of the poles could burn out due to excess load but in this instance coincidentally it is always the neutral.

Isn't it actually most commonly the vicinity of the L (pin/ receptacle/ terminals/ connections) that suffers thermal damage, the heat generation often originating from poor contact between fuse and 'holder'?

Kind Regards, John

It quite often is, but I'm afraid that it's the only thing I can come up with at the moment because I am not a believer of the 'mysterious neutral coming loose on it's own' scenario

 

[bernardgreen]

Unfortunately, in my experience, 13A plugs, sockets or FCUs do not like being ran constantly at or near 13A.

n the 1980's the GPO was one of those organisations which set a maximum load of 9 amps on 13 amp plugs. To have a higher load required special permission and the plug had to be of an approved manufacturer.

We did tests on several makes ( for use at remote un-attended sites ) and found some of the cheaper ones were so fault prone at much lower than 13 amps they could not be used in high reliabity situations.

 

[ricicle]

We did tests on several makes ( for use at remote un-attended sites ) and found some of the cheaper ones were so fault prone at much lower than 13 amps they could not be used in high reliabity situations.

I've had problems with MK plugs in MK sockets running at 12.7A ! (That's not to say that MK's quality is as good as it used to be!)

 

[JohnW2]

Isn't it actually most commonly the vicinity of the L (pin/ receptacle/ terminals/ connections) that suffers thermal damage, the heat generation often originating from poor contact between fuse and 'holder'?

It quite often is, but I'm afraid that it's the only thing I can come up with at the moment because I am not a believer of the 'mysterious neutral coming loose on it's own' scenario

... but it may never have been tight. It's not beyond the bounds of possibilities of human psychology and behavior that, "because it is the L' some of us may (subconsciously) be more rigorous in tightening L terminals than N ones.

Kind Regards, John

 

[ricicle]

... but it may never have been tight. It's not beyond the bounds of possibilities of human psychology and behavior that, "because it is the L' some of us may (subconsciously) be more rigorous in tightening L terminals than N ones.

Kind Regards, John

But I would sincerely hope in the OP's scenario that the neutral would have had special attention paid to it after three or four occurences !

 

[JohnW2]

... but it may never have been tight. It's not beyond the bounds of possibilities of human psychology and behavior that, "because it is the L' some of us may (subconsciously) be more rigorous in tightening L terminals than N ones.

But I would sincerely hope in the OP's scenario that the neutral would have had special attention paid to it after three or four occurences !

Well, one certainly might expect that - but it doesn't take much of study of human behaviour to find examples of people making the same mistake repeatedly, be it consciously or subconsciously. Were that not the case, few people would, for example, get seriously drunk more than once

Kind Regards, John