Plumber concerns

teepoo

Hi All,

I have some concerns about my plumber who I have asked to replace my 7.2 KW Gainsborough electric shower:

He has quoted a cash price of £85 to replace it with an 8.5 KW Mira Vie shower (which I pay for).

As I understand it, an 8.5 KW shower would require the fuse and wire to be upgraded (the wire is currently 6mm). He said that no upgrade will be required. Is he correct?

Thanks,
[FONT=&quot]Pete.[/FONT]

AdrianW2

You may have already found it, but there's a cable size calculator at TLC

macman

What fuse rating have you currently got on that circuit? According to the Mira site you need a 40A with RCD, Is an RCD already fitted?
That shower takes 35.5A compared to the existing one taking 30A.
Cable capacity depends on the length of the cable run. What's the approx run from the RCD and does it run on the surface, in conduit etc?

teepoo

The run is about 8 meters. I have not seen a RCD installed and am unsure of what the fuse rating is. The cable runs in the loft.

I did get a quote from another plumber (who has electrical qualifications). He said that since it was a straight swap (if I were to get a 7.5 shower), then no Part P certification was required. He quoted £110 to £120 for the work).

macman

An RCD is not a legal requirement, but you would be very foolish to install a new shower without fitting one, regardless of the power rating
The fuse rating will be marked on the fusebox feeding the shower circuit. Can you look at it and ID what type of unit it is?
OK, the cable runs from the loft down to the isolator switch near the shower (I do hope you have one of those fitted). But how does it run from the fusebox to the loft-in conduit or just wall clipped? Assuming it runs in conduit, I think you need a 10m cable for that run. And fit an RCD if not already installed. You may also need to uprate the isolator switch to take
35+A.
Did your other plumber say if a cable upgrade would be required if using an 8.5kw shower?

teepoo

He said that a cable upgrade would not be required, he made the same comment about a 9KW shower - which is why I am concerned about his electrical wiring knowledge. I will check the fuse tonight.

Thanks for the info.
Pete.

allan673

existing cable will be ok for an 8.5kw shower, anything bigger than an 8.5kw will need the cable replacing.

macman

teepoo wrote: »

He said that a cable upgrade would not be required, he made the same comment about a 9KW shower - which is why I am concerned about his electrical wiring knowledge. I will check the fuse tonight.

Thanks for the info.
Pete.

But no comment about the possible need to fit an RCD or uprate the isolator switch. Since your plumber is apparently not Part P registered, I'm not surprised that he doesn't think this work is necessary, because he's not qualified to do it himself.