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RCD Risk Assessment Permitted Exception

Harry Heathfield

I posted the same question to Reddit, plus here in the hope I can find someone with the knowledge/template.

Reddit post link for those who wish to reply there - https://www.reddit.com/r/ukelectricians/comments/10yu2hy/rcd_risk_assessment_permitted_exception/

I've copied the question below for those who prefer to reply here; thanks in advance!

Does anyone have a risk assessment example or template to support measures that would help with the permitted exception of RCDs in BS 7671, 411.3.3?

The use case is an industrial environment where skilled persons connect equipment/machinery for testing/commissioning purposes. There are two IEC 60309 (CEEFORM) outlets, one 63A and one 125A; 400 V 3P+N+E 6h.

Note - on the same site, there is a custom third-party distribution panel with 100mA RCD protection and a key switch capable of bypassing the RCD altogether (keys held by authorised persons). The company wants a similar arrangement in a new part of their building, hence the need for a risk assessment.

Edit - this is common practice in the related industry; up to 50+ VFDs can be connected to these circuits, which generate leak current via the filters.

Any feedback or support is welcomed!

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  • 0

    There is some guidance in the 9th Ed to IET Guidance Note 5, that wasn't in the previous Edition - see Section 8.2.3 (pages 64-65)

    Harry Heathfield said:
    he use case is an industrial environment where skilled persons connect equipment/machinery for testing/commissioning purposes. There are two IEC 60309 (CEEFORM) outlets, one 63A and one 125A; 400 V 3P+N+E 6h.

    Regulation 411.3.3 requires additional protection by RCD for socket-outlets with rated current up to 32 A - so the requirement is not coming from BS 7671.

    However, does BS EN 50191 apply ... as it's a test environment? This is more tricky.

  • 0 in reply to gkenyon

    Thank you for the material references; I will look at those in the office next week.

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