Linked MCB

nrg · Mar 3, 2011

Hi

Just looking at an oldish crabtree board and found two 32amp mcb's with 6mm cable on each linked with a 10mm on the outgoing side. This goes to a shower unit with 63amp rcd and 50mcb. Is this ok? I know it's not an ideal solution but is it safe? Shower is 11kw

Any advice would be good thanks

nrg · Mar 3, 2011

Just an update, both the 6mm are connected to the rcd shower unit

telectrix · Mar 3, 2011

are you saying that you've got 2 MCBs parallelled up, feeding a shower?

nrg · Mar 3, 2011

Yes that's what it looks like!

telectrix · Mar 3, 2011

think about it. turn off 1 mcb to isolate shower, you still got power to it through the other mcb. it's a definite NO. 11.5 kw is 50A, so it needs sorting ASAP. you should be OK with a 50A mcb. measure the actual current drawn with a clamp meter. probably be around 42 - 45A

Deleted member 26818 · Mar 3, 2011

It's not acceptable, both conductors should be in the same MCB.

nrg · Mar 3, 2011

This is what I thought! I reckon it's been done as it is an old type board and you can't get type 1 breakers! I know what the customer will say! "it's worked fine without any problems just leave it" what a pain! Anyone know where I can get a crabtree type 1 50amp mcb?

telectrix · Mar 3, 2011

are they starbreaker MCBs? i,ve got some, not sure what values. can you upload a pic?

nrg · Mar 3, 2011

No not star breaker, much older than that! They screw onto the buz bar! Not clip on! What a pain ;(

telectrix · Mar 3, 2011

only solution then is to split the tails, fit a separate CU with RCD and 50A MCB or RCBO. i would disconnect from existing MCBs if he won't pay for this. or get him to sign a disclaimer. end of.