MCB issues

[MasterAbacus]

Hi guys, id like some help with this one... and correcting if im wrong in my thaughts....

Yet another one of my Friends has been playing where they really shouldnt... and im going to pop along over the weekend and try sort a few things out.... From what ive been told here goes....

The Cooker trips the mcb when all hobs and oven are on, is a standalone fan electric (Sorry dont know the output atm), He has this on a 20a MCB, Apperently is was on a 32aMCB before he started playing.... he also has the Imerssion heater on a 40aMCB.....Works ok.... Cooker wired with 6mm to switch/socket.

My thaughts are he has wired these to the wrong MCB... ie the cooker should go n the 40a, and the Immersion on the 20a..... Yes/No ??


Also he has an issue with the shower, its a 9kw or 9.5kw, connected to its own CU, that fitted with a 63A RCBO and a 40A MCB, wired with 10mm cable. the shower works ok, but if they use it on full power (High setting), it trips after about 5 mins.... it can be run on half power(Med setting) for as long as they want.... Again my thaugths are this should be connected to at least a 45A MCB..Yes/No?

Really dont know why i bother sometimes, but would really lke some pointers on this before i go over and have a look. Also the only reason for the CU mcb issues is that he decided to swap around the MCB`s after a mate at work told him that he should have the highest ones nearer the Main trip..... why dont people leave alone.... and yes, ill be checking everything in the CU, just to make sure nothing else is suspect.

 

[Steve]

Your mate sounds like a danger to everyone around him. I hope he doesn't own a car. I would suggest you correct this fault, then lock up his consumer unit and give the key to his wife.

 

[viewer]

Your guesses are probably right, but as you say, you'll have to check each circuit. If he just moved the MCBs and the cables are unmoved, you might be able to confirm your suspicions by looking at the original positions and selecting the right MCB from the range provided. If you're right then all should agree with cable sizes as well as intended use.
Best of luck
V

 

[MasterAbacus]

Dont soppose any of the regular sparks have comments on this?

 

[briwire]

a 9.5kW showers takes about 41-42 amps so it will trip a 40 A MCB after a length of time. If he has 10mm cable like you say, it is perfectly OK to replace it with a 45A MCB.

The cooker should be on at least a 32A MCB, assuming that the cable is rated higher, ie 6mm.

The 3kW immersin takes around 13A so it needs a 16A or 20A if it is wired in 2.5mm.