Band I / Band II cct separation

mapj1:

Inside equipment, because it can be type tested for approval (think of a megger-like test) you can show that an alternative arrangement is possible.

For example on a PCB with primary and secondary votages on the same side, I'd expect clearances to be to IEC-60950-1

it very quickly gets confusing. c

Agreed - BS 7671 does NOT apply to pre-manufactured assemblies, which should comply with appropriate standards (Regulation 113.1).


BS EN 62368-1 (IEC 62368-1) supersedes BS EN 60950-1 (IEC 60950-1) and BS EN 60065, both of which are due to be withdrawn this year.

Of course you can fit  transformer in a CU. But unless the bellwires at 12 V or whatever coming out are over-sleeved to a standard that can hold off mains, you should really bring the ELV out in mains flex.

• Regulation 536.4.203 - i.e. is the transformer stated as suitable for installation in that CU by the manufacturer, or are you happy to take responsibility for the safety and EMC performance of the whole assembly?

• Regulations 444.6.1 and 444.6.2 i.e. is there adequate separation for electromagnetic compatibility of the Band I circuit? Regulation 444.4.1 lists switchgear as a "source of electromagnetic disturbance". It depends what the transformer is supplying, but an electronic door bell, for example, is unlikely to have been manufactured to consider the disturbances from switchgear, and it's possible that spurious operation of the bell, or damage to the electronics, could occur if there is not adequate physical separation. In the absence of further information, if we consider a 100 A DBO, Table A444.2 would recommend 600 mm separation distance from circuits carrying 100 A, 500 mm from circuits carrying 50 A, and 450 mm for 230 V circuits carrying less than 50 A.

mapj1:

Inside equipment, because it can be type tested for approval (think of a megger-like test) you can show that an alternative arrangement is possible.

For example on a PCB with primary and secondary votages on the same side, I'd expect clearances to be to IEC-60950-1

it very quickly gets confusing. c

Agreed - BS 7671 does NOT apply to pre-manufactured assemblies, which should comply with appropriate standards (Regulation 113.1).


BS EN 62368-1 (IEC 62368-1) supersedes BS EN 60950-1 (IEC 60950-1) and BS EN 60065, both of which are due to be withdrawn this year.

Of course you can fit  transformer in a CU. But unless the bellwires at 12 V or whatever coming out are over-sleeved to a standard that can hold off mains, you should really bring the ELV out in mains flex.

• Regulation 536.4.203 - i.e. is the transformer stated as suitable for installation in that CU by the manufacturer, or are you happy to take responsibility for the safety and EMC performance of the whole assembly?

• Regulations 444.6.1 and 444.6.2 i.e. is there adequate separation for electromagnetic compatibility of the Band I circuit? Regulation 444.4.1 lists switchgear as a "source of electromagnetic disturbance". It depends what the transformer is supplying, but an electronic door bell, for example, is unlikely to have been manufactured to consider the disturbances from switchgear, and it's possible that spurious operation of the bell, or damage to the electronics, could occur if there is not adequate physical separation. In the absence of further information, if we consider a 100 A DBO, Table A444.2 would recommend 600 mm separation distance from circuits carrying 100 A, 500 mm from circuits carrying 50 A, and 450 mm for 230 V circuits carrying less than 50 A.