Power Shower Feed, external run legal??

[miloharrisson]

Hello, hello, long time listner, first time caller...

So, I have an issue in a house I'm trying to get ready to rent. The plumber has installed a power shower despite my asking him to install a mixer type. He's not gonna come back and fix it, and I havent paid for shower.

The issue I have is getting power to the thing. I've literally just had it carpeted so really dont want to be ripping them up, and dont want to have to retile the bathroom. Then someone suggested running power around the outside. The house is an end terrace, and the consumer unit is on an outside wall. I'm wondering if there is anything in the regs that would prevent me running a high csa flex around the outside and drilling thru the wall at each end??

Around 14m run and 8.5kw, I make it 6mm2 flex

All help gratefully recieved

Regards

Milo

 

[MJPD29]

Running outside with cable is fine. Wouldn't use flex though, swa more suitable.

 

[miloharrisson]

Hey, thanks for your reply! I didn't think swa would be required as it'd start a 2m above ground, and run straight up to 3.5 odd?

 

[LewisM]

Can't really use flex as a supply cable, use NYYJ as it's UV stable has relatively decent mechanical protection and it's easily available by the meter.

6mm² 3 Core NYY-J Cable Black - 100Mtr Drum

 

[davesparks]

Can't really use flex as a supply cable, use NYYJ as it's UV stable has relatively decent mechanical protection and it's easily available by the meter.

6mm² 3 Core NYY-J Cable Black - 100Mtr Drum

Why can't you use flex?

 

[pc1966]

H07RN-F flex with ferrules on the ends would be acceptable if it is adequately supported and not at risk of damage as it is outdoor/UV resistant. NYY-J is stiffer and tends to sit better, and no need for ferrules.

One thing about going out through a wall and along is to take care of the cable's minimum bend radius. Typically that is 6-8 times the cable diameter and for 6mm 3C it ends up about 10cm, i.e. think of wrapping around a 20cm / 8" diameter pipe. It is big by wall exit standards!

Using some 25mm PVC conduit outside and 6mm T&E might be better as it can bend tighter in the "flat direction" if done with care to line up that way. The conduit would protect against UV light and looks nice and straight (assuming well installed with support saddles at sensible intervals). Something like these at the two ends so the cable can exit through the centre it to the wall's hole:

25mm PVC Conduit Terminal Box Black (Sold in 1's)

Provision for brass earth terminal

www.cef.co.uk

 

[LewisM]

Why can't you use flex?

Just seems rough to me but you are correct

Regulation 521.9.1 permits the use of flexible cables for fixed wiring if they’re of the heavy duty type or the risk of damage is low or protection against mechanical protection is provided.

 

[littlespark]

You wanted a mixer, so why can’t another plumber supply and install a mixer?

It might be a simpler solution than external wiring.

The circuit would require rcd protection and need to go through an isolator at the bathroom before the shower. Plus working at height outside…

 

[Taylortwocities]

The plumber has installed a power shower despite my asking him to install a mixer type.

I assume that your DHW is heated with a gas boiler? If so, remember that electricity is more than 3 times the cost of gas, so you'll be paying £££ for the plumber's mistake every time you have a shower.

I totally agree with Littlespark.

You wanted a mixer, so why can’t another plumber supply and install a mixer?

It might be a simpler solution than external wiring.

 

[brianmoooore]

We've had this on here before - the OP says 'power shower'. That's a conventional mixer shower using a pump to increase the flow rate, NOT a shower that uses large amounts of electricity to heat cold water.
The OP might have meant 'electric shower' of course, but that can't be assumed.