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Assessment of Protective Measures for an 12kW Electric Boiler Installation

AMK

I seek your insights on an observation made during an Electrical Installation Condition Report. A 12kW electric boiler has been installed within the electrical meter cupboard, in proximity to the consumer unit. The installation incorporates 16mm tails drawn from the line side of an 80Amp RCD housed in the installations split consumer unit feeding an additional 63amp 61008 RCD positioned within 3 meters, with the 12kW boiler directly connected to the load side.

The boiler is a fixed load and reliant on the Distribution Network Operator’s protective device for protection against overload and short circuit (L-N) fault currents. There were no evident signs of thermal overloading on any devices. It seems that earth fault protection is managed by the additional 63 Amp RCD within its own enclosure, while protection against overload and short circuit fault currents is afforded by the DNO’s equipment. The prospective short circuit current at the boiler measures 0.793kA and the DNO’s device is a 100 Amp BS 1361 type 2B.

What are your thoughts on if there is a requirement for any remedial action based on these findings?

Parents

  • Single phase, no dedicated fuse, MCB or RCBO ? 

    Reminds me that at one time it used to be quite common to find cookers and showers on the wrong side of the main switch in the "shallow end" accommodation the days of the hot wire wylex boards. Rough. 100A is a very loose fit to the correct rating.

    Not good, and I suspect if the DNO were aware they'd be wanting it changed.

    I'd have preferred Henley blocks to split tails and an  MCB or RCBO in the box not just an RCD. I am not sure it is actually an immediate danger exactly but certainly a cowboy job of the 1st order !

    What else have they done wrong ? And is the plumbing actually correct - in terms of overflows pressure relief or whatever ?

    Mike

    minor typo edits.

  • in reply to mapj1

    Hi Mike, thanks for your response. To clarify, the system is single-phase supply and has a dedicated 61008 RCD, without an additional overcurrent protection device, only the bullet. The plumbing arrangements seem to be in order. I agree with you on the henly block arrangement is how it should have been done to start with. I suppose it will come down to what the DNO have to say about it. 

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  • in reply to mapj1

    Hi Mike, thanks for your response. To clarify, the system is single-phase supply and has a dedicated 61008 RCD, without an additional overcurrent protection device, only the bullet. The plumbing arrangements seem to be in order. I agree with you on the henly block arrangement is how it should have been done to start with. I suppose it will come down to what the DNO have to say about it. 

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