B
benmatthews
Hi Peeps. I'm having an issue wiring in a new shower in my house that I'm having trouble working out. I initially wired in a 8.5kw Tritn shwer thats a few years old but had never been used and kept in the box. I ran the circuit in 10mm T & E (circuit length 15 metres). I installed a 45A pull switch/Isolator between the consumer unit and the shower. The circuit is on a 40A MBC which is then protected by a 30mA RCD. Cable size and MBC size are exactly what it says in the instruction manual for an 8.5kW model.\
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I connected everything up and carried out the commisioning as per the manual where the shower is turned on the cold water setting where only the pump is engaged and not the heating element, and the water is pumped through the shower to eleiminate any air in the system etc. \
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The shower runs absolutely fine on the cold setting, but as soon as I turned the power setting to heat the water it's trips out the RCD. I checked all the connections which were fine. I initally thought perhaps the loading was tripping out the RCD when heating. However, I discovered that I could still trip the RCD when not under load by having the MCB turned off, the pull switch in the on position, the shower button off, and as soon as I turned the dial from cold to hot setting the RCD would trip? I assumed then that perhaps there must have been some sort of earth fault within the heating element of the shower so went out and bought a new triton 8.5kW shower.\
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I have plumbed/wired the new shower in, commisioned it on the cold setting which runs fine, and low and behold once again, as soon as I turn the dial to engage the heating element it trips out. With the new shower, it does not trip out the RCD when the MCB is isolated as with the older version, it only trips out when under load.\
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I'm at a bit of a loose end now as what to look for. I have checked the cable to see if there are any nicks anywhere and can't see anything obvious. There is about 60cm of cable hidden behind some plywood that has been tiled over I can't check without pulling it all down but I was careful screwing in the ply not to put any screws where the cable run was.\
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I would have thought that if I'd nicked the cable with a screw it would trip when on the cold setting but it doesn't\
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I don't have a megger so cannot IR test the cables (I would like to). Does anyone have any other ideas as to what the issue could be, otherwise I'm going to have to get in a spark with testing equiptment which I'd like to avoid if possible.\
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Thanks in advance\
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Ben\
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I connected everything up and carried out the commisioning as per the manual where the shower is turned on the cold water setting where only the pump is engaged and not the heating element, and the water is pumped through the shower to eleiminate any air in the system etc. \
\
The shower runs absolutely fine on the cold setting, but as soon as I turned the power setting to heat the water it's trips out the RCD. I checked all the connections which were fine. I initally thought perhaps the loading was tripping out the RCD when heating. However, I discovered that I could still trip the RCD when not under load by having the MCB turned off, the pull switch in the on position, the shower button off, and as soon as I turned the dial from cold to hot setting the RCD would trip? I assumed then that perhaps there must have been some sort of earth fault within the heating element of the shower so went out and bought a new triton 8.5kW shower.\
\
I have plumbed/wired the new shower in, commisioned it on the cold setting which runs fine, and low and behold once again, as soon as I turn the dial to engage the heating element it trips out. With the new shower, it does not trip out the RCD when the MCB is isolated as with the older version, it only trips out when under load.\
\
I'm at a bit of a loose end now as what to look for. I have checked the cable to see if there are any nicks anywhere and can't see anything obvious. There is about 60cm of cable hidden behind some plywood that has been tiled over I can't check without pulling it all down but I was careful screwing in the ply not to put any screws where the cable run was.\
\
I would have thought that if I'd nicked the cable with a screw it would trip when on the cold setting but it doesn't\
\
I don't have a megger so cannot IR test the cables (I would like to). Does anyone have any other ideas as to what the issue could be, otherwise I'm going to have to get in a spark with testing equiptment which I'd like to avoid if possible.\
\
Thanks in advance\
\
Ben\
