RCDs and three-phase sockets

Published: 1 May 2019 Category: Q&A

A Voltimum user asks whether they need to provide protection for external three-phase socket outlets.

This Q & A is one of the thousands posted in our Technical Expertise area and answered by our Voltimum Experts.

Question:

Do the RCD requirements of the 18th Edition apply to 3-phase socket outlets?

Answer:

Gary Parker - Senior Technical Support Engineer, ECA

Regulation 411.3.3 does not stipulate any difference between single- or three-phase outlets. It states:

411.3.3 Additional requirements for socket-outlets and for the supply of mobile equipment for use outdoors.

In AC systems, additional protection by means of an RCD with a rated residual operating current not exceeding 30 mA shall be provided for:

(i) socket-outlets with a rated current not exceeding 32A, and
(ii) mobile equipment with a rated current not exceeding 32A for use outdoors.

An exception to (i) is permitted where, other than for an installation in a dwelling, a documented risk assessment determines that RCD protection is not necessary.

So there is still the option for omitting the RCD via a risk assessment.