BS7671;2018 Minor works certificates.

I think the references to RCD testing in Part 6 of the 18th are a dogs breakfast.


In 643.8 the a shining example of ambiguity in the Note to the regulation. It needs to be understood that Notes do not create a regulation in themselves but are only guidance so not a "shall" or "shall not". You may have an RCD that is stickier than sticky the stick insect and it will operate at 5x Idelta n or higher or give it a jolt with 2A, 5A or more and it will operate and give you a very fast disconnection time. What does this prove? 


As Graham K has pointed out that in Appendix 3  Table 3A you will find the the test currents and times for RCD product standards (BS EN 61008 and 61009). My view is that RCDs should meet this standard and that means they should trip in the stated  times set out in the standard. If an RCD does not trip at 1 x Idelta n then it is defective. This softer test is a better indicator of RCD health than the 5 x test and consumer safety.


643.7 compounds the ambiguity as it applies to RCDs used for fire protection and fault protection. It seems to suggest that if you have carried out an earth continuity test which is satisfactory on installations that rely on an RCD for fault protection, and the RCD gives you a disconnection time that meets the appropriate time for the type of circuit and earthing system, you do not then need to carry out earth loop impedance testing so would put N/A in the column on the form. It does not indicate a test current but refers you Table 3A of Appendix 3. 


All of the references to RCD testing require the test to be carrier out using an instrument that complies with BS EN 61557-6. Those instruments have functions that will test at both X1 and  X5 tripping currents at both halves of a full cycle. Most modern instruments  have an auto function that runs through the tests and stores the test results for examination post test.


My view is, for both fire and fault protection, the RCD should be tested a X1 tripping current on both half cycles and the highest test result recorded. As you were probably taught on the C&G I&T courses you don't do a X 5 test for fault protection and you carefully avoided the trap exam question when asked what is the maximum test current for a 100mA RCD.


The new Appendix 6 test forms only have one column for the RCD test result. My view is that you should enter the highest time out of the applied tests.


The new Stroma software forms that will soon be launched will have have both X1 and X 5 columns on the test sheets.

I think the references to RCD testing in Part 6 of the 18th are a dogs breakfast.


In 643.8 the a shining example of ambiguity in the Note to the regulation. It needs to be understood that Notes do not create a regulation in themselves but are only guidance so not a "shall" or "shall not". You may have an RCD that is stickier than sticky the stick insect and it will operate at 5x Idelta n or higher or give it a jolt with 2A, 5A or more and it will operate and give you a very fast disconnection time. What does this prove? 


As Graham K has pointed out that in Appendix 3  Table 3A you will find the the test currents and times for RCD product standards (BS EN 61008 and 61009). My view is that RCDs should meet this standard and that means they should trip in the stated  times set out in the standard. If an RCD does not trip at 1 x Idelta n then it is defective. This softer test is a better indicator of RCD health than the 5 x test and consumer safety.


643.7 compounds the ambiguity as it applies to RCDs used for fire protection and fault protection. It seems to suggest that if you have carried out an earth continuity test which is satisfactory on installations that rely on an RCD for fault protection, and the RCD gives you a disconnection time that meets the appropriate time for the type of circuit and earthing system, you do not then need to carry out earth loop impedance testing so would put N/A in the column on the form. It does not indicate a test current but refers you Table 3A of Appendix 3. 


All of the references to RCD testing require the test to be carrier out using an instrument that complies with BS EN 61557-6. Those instruments have functions that will test at both X1 and  X5 tripping currents at both halves of a full cycle. Most modern instruments  have an auto function that runs through the tests and stores the test results for examination post test.


My view is, for both fire and fault protection, the RCD should be tested a X1 tripping current on both half cycles and the highest test result recorded. As you were probably taught on the C&G I&T courses you don't do a X 5 test for fault protection and you carefully avoided the trap exam question when asked what is the maximum test current for a 100mA RCD.


The new Appendix 6 test forms only have one column for the RCD test result. My view is that you should enter the highest time out of the applied tests.


The new Stroma software forms that will soon be launched will have have both X1 and X 5 columns on the test sheets.