Under rated mcb

[scott_369]

Basically ive moved into a house with some questionable electrics most of which has now been rectified but ive come across another potential problem. 

Our shower has rceently died. It only runs cold water so im assuming its the heating element thats gone.

Its a 9.5kw shower 

Shower pull cord is 45amp 

Mcb is 32amp 

Does this mean that the shower could not pull more than 32amp

Any reason why the pull cord is higher than the mcb

Is this likely to be linked to why the shower has died. 

Or is this completely normal and i am over reacting due to previous issues.

Thanks

 

[binky]

the MCB will be dependent on the cable size, but 32Amp isn't enough for a 9.5kW shower. It will work, but for about 10mins max. Shower isolators are usually 45Amp. You need to check cable sizes, but this would not cause the shower to fail.

 

[Rrrrr]

Has the MCB tripped?

The pullcord will be larger than the MCB as it has to break the full load current. The 9.5 Kw shower will pull approx 38 amps so should be on a 40 amp MCB, however do NOT fit a bigger MCB before checking if the cable size is large enough.

You say you've just moved in, do you have any recent test certificates?

 

[scott_369]

the MCB will be dependent on the cable size, but 32Amp isn't enough for a 9.5kW shower. It will work, but for about 10mins max. Shower isolators are usually 45Amp. You need to check cable sizes, but this would not cause the shower to fail.

Thanks for that im assuming if the shower pulled any more than 32amp the mcb would cut out then. Shower is not used for very long so it has never happened.  Assume it would cut out before the cable, pull cord or shower etc overheated. 

Would an 8.5kw shower be ok on a 32amp

Thanks

Has the MCB tripped?

The pullcord will be larger than the MCB as it has to break the full load current. The 9.5 Kw shower will pull approx 38 amps so should be on a 40 amp MCB, however do NOT fit a bigger MCB before checking if the cable size is large enough.

You say you've just moved in, do you have any recent test certificates?

No the mcb never tripped, just one day turned the shower on and it wouldnt heat up. 

No recent certificates i say recently moved in we have been in a while and keep noticing nee issues

 

[scott_369]

Basically is this dangerous or will it just cut out after too long/trying to pull too much. 

 

[Lurch]

Basically is this dangerous

Not in the slightest.

 

[ProDave]

If the mcb had tripped, the shower would stop. I'll bet it's not on for long if it's running cold!!!!  a 32A mcb won't trip the second it goes to 33A, as Binky said at 40A it would not trip for about 10 minutes.

Best get someone to check it. but depending on the cable size you might have to go down to a smaller shower. If the cable is okay for a 9.5KW shower then the mcb will need to be changed for a larger one.

Is it really running "cold" or just "tepid"  Most showers have two heating elements and recently I had one where one element had gone.
 

 

[scott_369]

If the mcb had tripped, the shower would stop. I'll bet it's not on for long if it's running cold!!!!  a 32A mcb won't trip the second it goes to 33A, as Binky said at 40A it would not trip for about 10 minutes.

Best get someone to check it. but depending on the cable size you might have to go down to a smaller shower. If the cable is okay for a 9.5KW shower then the mcb will need to be changed for a larger one.

Is it really running "cold" or just "tepid"  Most showers have two heating elements and recently I had one where one element had gone.
 

Sorry i meant when it was working/heating it wasn't used  for long.

No its ice cold definitely not tepid. 

Yea it has 2 elements  (well im assuming based on the settings) and both are freezing cold.

If i need the shower replacing i will look at 8.5kw would that be suited to a 32amp? 

Im assuming when it was working the shower was pulling more than 32amp but the mcb would trip when it gets to a dangerous amount/length of time.

 

[binky]

if you are unlucky the cable might be 4mm, hence the breaker, but basically that MCB is suitable for more like 7.5kW. Get some one to check the circuit properly and it will answer your questions. I doubt you have an RCD for that circuit either which is highly recommended.

 

[ProDave]

If it's gone suddenly and gone to stone cold, then it's more likely the internal safety thermostat that stops it delivering scalding hot water that has failed, rather than the heating elements. Or the switch that detects water flow and stops it boiling if there is no flow.  It might be repairable. But do get the cable size checked then you can make a decision to repair, replace with same size, or replace with a smaller one.
 

 

[kerching]

Basically ive moved into a house with some questionable electrics most of which has now been rectified but ive come across another potential problem. 

Our shower has rceently died. It only runs cold water so im assuming its the heating element thats gone.

Its a 9.5kw shower 

Shower pull cord is 45amp 

Mcb is 32amp 

Does this mean that the shower could not pull more than 32amp

Any reason why the pull cord is higher than the mcb

Is this likely to be linked to why the shower has died. 

Or is this completely normal and i am over reacting due to previous issues.

Thanks

Have you checked the pull,switch is working correctly?

most shower pull switches are junk

if switch has failed fit a new Crabtree one...or get an electrician to do it. Specify it HAS to be Crabtree

 

[scott_369]

Thanks for the replies guys

I will get someone out asap to try and check what is broken on it and if it is repairable then. I will get the wire sizes checked at the same time 

My main concern was that the mcb rating would be making it unsafe but i assume its making overly safe if anything. And it hasnt effected it so far

Thanks

 

[scott_369]

Have you checked the pull,switch is working correctly?

most shower pull switches are junk

if switch has failed fit a new Crabtree one...or get an electrician to do it. Specify it HAS to be Crabtree

Its a crabtree pull cord and is still working 

Had plenty of problems with them in the past as well so first thing i checked