Shower wiring, warm neutral

[duncb]

Information required please,
I have a 9.5 KW shower which is powered from the consumer unit with a Wylex 63amp load /30ma trip RCD through a 40amp MCB then on to 50amp MK pull switch then to the shower all run in 10mm cable. Distance from consumer unit to shower approx. 15 meters with wiring run through cavity wall then through loft.
My question is following a problem with burnt neutral wires in the consumer unit which my electrician said was almost certainly caused by a loose connection as he found others loose I have noticed that when having a shower the neutral wire is getting warmer than the live wire.
Using a non contact thermometer at the consumer unit connections the live wire is approx. 25degrees whilst the neutral is around 46degrees also if you touch the RCD casing the neutral side is warmer.
All shower terminals have been checked and tightened and the shower has been in use for approx. 8years,
Is this normal and I am being paranoid or do you think I have a problem somewhere and if so any suggestions before I call the electrician back.
AS far as I know it could have been like this for years and never noticed.
Sorry to drag on but tried to give as much info as poss to start off with.
Thanks Dunc.

 

[ban-all-sheds]

All shower terminals have been checked and tightened

So is this overheating being seen after the tightening?

If cables or terminals have been damaged by earlier overheating then they may need cutting back to undamaged conductors or replacing - they will always present a high resistance joint.

But 46° is not enough to damage anything.

 

[duncb]

Thanks for quick reply.

Yes the temperature readings were checked after all connections tightened,and the cable was cut back to clean wire as there was plenty to spare.
As I said it could have been like this before and just gone unnoticed it was just through keeping an eye on following repair I noticed this.
It is the temperature difference between the two cables that puzzled me as I thought they should have been similar.

 

[craftor]

Probably a bit late, just noticed your problem
There shouldn't be such a temp difference as the live & neutral current should be equal, at least within 30ma or the RCD would trip

It sure sounds like damage to the neutral conductor ie. a cut or narrowing which lessens the csa

If you can check the live and neutral resistances end to end with a long lead this will prob show a higher resistance in the neutral

My concern is this might only get worse and and eventually become a fire hazard