Published: 4 February 2015
Category: Q&A
Hamish asks this question about bathroom lighting that dims when the electric shower is turned on, and the reason for this problem. It has been answered by the ECA (Theme - Installation Tips):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: I've just finished an house extension for a customer who required a 9.5kW electric shower wired in 10mm and having a 40A circuit breaker, one ring main (11 doubles), two lighting circuits with approximately six lights on each, plus a smoke alarm.
I’ve installed a dual RCD mains board with an RCD feeding the above circuit's various MCBs.
However, when the electric shower is switched on, the lights dim until the shower is switched off. What is the reason for this, do you think?
Answer: This could either be an incoming supply rating issue (too small).
Alternatively, this problem could be caused by a loose connection.
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