{"id":389,"date":"2017-06-29T14:19:28","date_gmt":"2017-06-29T14:19:28","guid":{"rendered":"http:\/\/www.the-regs.co.uk\/blog\/?p=389"},"modified":"2017-06-29T14:19:28","modified_gmt":"2017-06-29T14:19:28","slug":"installing-a-shower-electrically","status":"publish","type":"post","link":"https:\/\/the-regs.co.uk\/blog\/?p=389","title":{"rendered":"Installing a Shower – Electrically !"},"content":{"rendered":"

Wiring a Shower.<\/h1>\n

Perhaps one of the easiest circuits to install is the one that feeds a shower. Although it’s just a simple radial circuit there are a few pit holes you’ll need to avoid. We are going to assume that we are dealing with a domestic installation and as such Volt Drop will not be an issue, unless the shower is on the 3rd floor over on the east wing.<\/p>\n

Size of cable required?<\/h2>\n

More than likely it will be a 10kW shower these days and it will use 10000\/230 = 44A. So, we’ll need a cable that can carry 44A or more.<\/p>\n

Looking at Table 4D5 BS 7671 we see that if we have the cable clipped direct (ref method C) we could use a 6mm sq twin and earth as it will carry up to 47A<\/p>\n

However, it’s not a simple as that and it’s also highly unlikely that it’s going to be clipped directly throughout the building and we must allow for that.<\/p>\n

Taking the scenic route and avoiding too much thermal insulation we’ll settle for reference method 100 and this will give us 45A current carrying capacity for a 10mm sq twin and earth<\/strong>.<\/p>\n

Size of circuit breaker?<\/h2>\n

Have a look at Table 41.3 in BS761, not for the maximum Zs values for these circuits but for the size of circuit breakers commonly available.<\/p>\n

You’ll notice that there is a 40A circuit breaker but, that would be too small as every time the shower was switched on it would trip. The next one shown is a 50A circuit breaker, but again this is no good as it is higher than the current carrying capacity of the 10mm sq cable (45A).<\/p>\n

We can do one of two things.<\/p>\n

Put a bigger cable in with a 50A circuit breaker – 16mm will carry up to 57A ref method 100. Good luck getting that in the pull switch though. Or…<\/p>\n

Use a 45A circuit breaker! This will protect the cable against overload and they are available just not listed in BS7671. They are listed in the On-Site Guide, Table B6 along with the maximum Zs (80%) value.<\/p>\n

So, it’s 10 mm sq cable and a 45A Type B BSEN 60898 circuit breaker.<\/strong><\/p>\n

But there’s more. According to Part 7 Section 701 BS7671 (701.411.3.3) we are also going to need Additional Protection using a 30mA RCD.<\/strong><\/p>\n

Other things to consider…<\/h2>\n