Published: 19 September 2014
Category: Q&A
Mike asks this question, which is about whether it is OK to wire two or three instantaneous water heaters on the same radial circuit. It has been answered by the NICEIC (Theme – Regulations and Legislation):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: Should instantaneous water heaters be wired on their own circuit, or is it acceptable to wire two or three of them on the same radial circuit?
Answer: Ideally, these pieces of heating equipment should be on their own circuit because of the nature of the loading and the high current that is likely to be taken. This is mentioned in the ‘On Site Guide’ to the Wiring Regulations. See Appendix H5 p177 and BS 7671 Section 554.1 p175 'electrode water heaters and boilers'.
However, please note that, if this is an existing arrangement, then consideration must be given to the effects of overload and inconvenience on the circuit.
Regulation 314.1 mentions division of installation and the requirement for safe inspection and testing and maintenance.
All of these factors must be considered when designing the circuit arrangement.
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