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Earth Continuity Test and Polarity Test following when replacing low voltage single phase fixed electrical equipment

Rob Bain
Hi all,

Would appreciate your thoughts on the need to undertake Earth Continuity tests and Polarity tests following replacement of single phase low voltage fixed electrical equipment such as tea boilers / heating pumps / immersion heaters etc, that are supplied either from a switched and/or fused connection unit or an isolator. The existing electrical supply cable is going to be re-used as the equipment being replaced will be like for like, so there is no increase in load, no requirement to undertake a design.

This enquiry has been put forward as it is anticipated that (some) engineers, who have a mechanical background but with limited electrical knowledge (safe isolation), would be able to carry out the replacement of certain items of plant once they have completed some competency training followed by assessment and sign off by the company's NIC EIC QS. 


Thanks in advance.

Rob
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  • 0
    Hi.


    After reading some of these posts it seems most are making the assumption, that the installation was correct before you started with your minor works,


    But once you have fitted something new to an old circuit, you become responsible for it.  As for polarity we all check we have connected every thing as it should be.  But a polarity check makes sure everything in the circuit  before our work was correct. Without a polarity check a switch or MCB could be in the neutral and all we have done is added a little flex. but would leave you responsible for any problems in the future.


    as for the ZS reading just this Friday, I was tasked with fitting a switch fuse spur for a garage door my R1 + R2 was just 0.11 ohms, but ZS was 1.74 ohms too high for the protective device.  When I checked the supply cable to garage the sub main protective device, was all ready compromised. so the protective device would not operate in time. so left my work disconnected even though I had a lot of pressure from my line manager to connect it,


    so I see testing firstly protecting you from prosecution, then the customer who is the final user from harm. so my thoughts are its extremely important to do tests regardless on how small an input you have made to a circuit.
Reply
  • 0
    Hi.


    After reading some of these posts it seems most are making the assumption, that the installation was correct before you started with your minor works,


    But once you have fitted something new to an old circuit, you become responsible for it.  As for polarity we all check we have connected every thing as it should be.  But a polarity check makes sure everything in the circuit  before our work was correct. Without a polarity check a switch or MCB could be in the neutral and all we have done is added a little flex. but would leave you responsible for any problems in the future.


    as for the ZS reading just this Friday, I was tasked with fitting a switch fuse spur for a garage door my R1 + R2 was just 0.11 ohms, but ZS was 1.74 ohms too high for the protective device.  When I checked the supply cable to garage the sub main protective device, was all ready compromised. so the protective device would not operate in time. so left my work disconnected even though I had a lot of pressure from my line manager to connect it,


    so I see testing firstly protecting you from prosecution, then the customer who is the final user from harm. so my thoughts are its extremely important to do tests regardless on how small an input you have made to a circuit.
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