shower unit tripping mcb

[alan w]

recently my (triton opal)9kw shower has started tripping the mcb after about 10 mins of use.its run in 6mm about 6meters long and the supply from the mcb does get very warm.suggestions as to why this happening all of a sudden.

 

[andy]

whats the rating of ur MCB? is should be at least 40A and shud be in 10mm cable


EDIT: and when u say the supply fomr the MCB gets warm, do u mean the cable?

 

[plugwash]

remember running at full rated current means a core temp of 70 celcuis

warm therefore would be expected on a cble near its limit.

mcbs of a particular type and value are permitted to have wuite a range of charachteristics and they can change with age especially if overloaded

if its a 32A mcb then provided the cable doesn't run though any thermal insulation you should be able to uprate it to a 40A and this should solve your problem.

 

[alan w]

remember running at full rated current means a core temp of 70 celcuis

warm therefore would be expected on a cble near its limit.

mcbs of a particular type and value are permitted to have wuite a range of charachteristics and they can change with age especially if overloaded

if its a 32A mcb then provided the cable doesn't run though any thermal insulation you should be able to uprate it to a 40A and this should solve your problem.

thanks for info plugwash,,i will replace 6mm cable with 10 mm .all other factors which might cause problem are in place.

 

[alan w]

whats the rating of ur MCB? is should be at least 40A and shud be in 10mm cable


EDIT: and when u say the supply fomr the MCB gets warm, do u mean the cable?

thanks for reply.mcb rated at 63A.cable get warm on load side.as you say i will change to 10mm cable

 

[andy]

whats the rating of ur MCB? is should be at least 40A and shud be in 10mm cable


EDIT: and when u say the supply fomr the MCB gets warm, do u mean the cable?

thanks for reply.mcb rated at 63A.cable get warm on load side.as you say i will change to 10mm cable

AFAIK, 63A MCB's dont exist. and if it did, then 6mm cable would have melted before it tripped

as plugwash said, you need a 40A MCB and 10mm cable

 

[plugwash]

iirc contactum hager and wylex all do 63A mcbs but only in thier 10KA industrial range

some makers even do 100A mcbs though they are double width and don't connect directly to a busbar

beyond that you are into MCCB territory

 

[Damocles]

Does this shower have thermostatic control? It is winter now, so the water going in will be colder, and you may want it heated more too. So perhaps it IS using more power now. An overloaded mcb will not trip instantly unless it is a big overload. Adding a bit of load might just be enough so it trips now before you finish the shower.