Remember that effective communication is a two-way street, and it’s important to listen to others’ perspectives as well as expressing your own. Instead of saying “no,” you could try saying “I disagree” or “I see things differently.” This can help keep the conversation constructive and productive. I hope this helps.

AMK said:

I hope this helps.

No.

A further thought ...

The terminals of MCBs, RCBOs, etc. all seem to be the same size whether they be 63 A or 6 A devices.

The neutral pole is many times the first suspect also on a shower pull switch if your shower draws more current than the switch can handle. What are your thoughts? 

There have been several discussions on that very subject (and not just on overloads). Several theories abound, but my favourite is that shower pull switches (especially the types with terminals on the "faceplate") are very easy to create loose connections (as large stiff conductors, typically held by a small single screw attempt to twist as they're pushed back into the backbox) - that should happen equally with L and N of course, but then a loop test (or R1+R2) is done - so loose connections on L are much more likely to be spotted and therefore corrected; while on the other hand none of the standard tests check N continuity, so loose connections there are much more likely to go into service.

   - Andy.

AJJewsbury said:

shower pull switch

I am asumming that it is located in the room of the shower and thus is exposed to high humidty and ingress when the shower is in operation.  What IP rating does the shower pull switch have other than a very basic IP2x ?

That sounds good, though how often does an R1/2 test result in a re-tightening of the terminals?  - maybe for some folk, but personally I'm struggling to think of a time. Generally it seems either pass or fail by miles because some vital part  is actually missing - being off  by fraction of an ohm is not a thing that happens to me, unless the cable length/ type is wrong.

Mike

Moisture ingress wouldn't account for why (empirically) N terminals suffer more than L ones.

  - Andy.

Good point.  I would expect to see both terminals with the same issue.  Could that question be put to the manufacture maybe.  So someone like MK add their thoughts on why the N burns out more often than the L in a shower pull cord.  I am summing that the L and N terminals are built the same. 

I agree. If a terminal screw is making light contact, it will pass a loop test. It is when a current of 40 A is drawn that problems arise.

I strongly suspect that there is observer bias going on: over-heated neutral terminals get mentioned more often and once the myth has been established, it perpetuates itself.

Hi Folks,

So I raised this problem quite some time ago with regard to a caravan camp site where the owner was having the local pitch MCB being replaced at random due to over heating of the neutral connection on the MCB.

At the time I could not explain what was going on.

Since then I have been involved in a more serious example of the same but devices were being burnt out, cables were melting and protective device were tripping randomly.

The answer/ cause.............................................Harmonics.......................yep the one every body hears about but sometimes do not realise its a real world issue.

My conclusion is that modern mobile caravan/ campers etc. use numerous dc/ac inverters and converters for their vehicle and camping needs and often LED source illumination and other devices.

I suspect that these items vary in quality and may well be producing harmonics which are resulting in sub distribution harmonics and excessive neutral current well beyond the rated values of the devices specified for the "normal" expected running loads.

There are some good inline filters that could be fitted which prevent such harmonic distortion and effects and I for one will be giving this aspect of electrical design more consideration in future.

I have kept it short but believe thats the problem.

Cheers

DMB