Replacing old shower - melted junction block inside

[melodymaker67]

I have to replace an old gainsborough Energy 2000 shower (9.5kw) with a new Mira go (9.5kw). I have watched on Youtube how to replace a shower and my DIY skills are able to do this. The only thing troubling me is the junction box inside the shower has some time melted around the wires (a couple of years ago) as the shower hasn't worked well for some time. Only gets hot in the summer. I suspect (after looking on Google) that it could have been lose connections that has caused this. There is a main switch in the airing cupboard but this has been jammed on for some time. There is no RCD , just a trip switch on the board in the kitchen for this.

I am not an electrician but I should like to replace the swicth and shower myself as I cannot get an electrician who is interested on either My Builder.com or rated People. Nobody has responded.

Any advice would be appreciated. By the way, the switch has been opened for the photo to show how it's wired. Of course it is normally closed.

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[securespark]

Loose connection on neutral.

But the line is damaged too.

You will need to find some slack on the cable to cut back.

That's 6 milli cable: how long is the run back to the board and is the cable covered in insulation?

Is there an RCD protecting that circuit?

What rating is the DP switch and the protective device at the board?

Have you got PEB's to Gas and water mains and supplementary bonding in the bathroom (unless every bathroom circuit is RCD protected)?

 

[melodymaker67]

Loose connection on neutral.

But the line is damaged too.

You will need to find some slack on the cable to cut back.

That's 6 milli cable: how long is the run back to the board and is the cable covered in insulation?

Is there an RCD protecting that circuit?

What rating is the DP switch and the protective device at the board?

Have you got PEB's to Gas and water mains and supplementary bonding in the bathroom (unless every bathroom circuit is RCD protected)?

You have to understand we inherited this system when we bought the house so I can't answer some of your technical questions. Looks like I will have to get an electrician. The only circuit the shower is on is this, no RCD.

 

[securespark]

Main linked switch lever looks a bit wonky.

Gaps in board need closing off.

Looking at old shower manual, a nominal rating of 9.5kW at 240V = 8.7kW at 230V.

9.5kW @ 240V = 39.6A
8.7kW @ 230V = 37.8A

So, the 40A breaker should be good.

And the cable CCC should be good as long as there is no insulation involved.

 

[melodymaker67]

Ok, thanks for that. Do you think it would be ok to fit the new 9.5 Kw Mira myself or still hire a spark ? Also, any idea what could cause the bathroom switch to jam ?

 

[securespark]

It likes Bob Marley?

(a) The mechanism could be failing.

(b) Sometimes I have know grit get inside a switch mechanism and jam it.

Or more likely,

(c) there is a loose connection and the switch is heat damaged.

Opening it up would be interesting to see... but you won't get it back together again!!

 

[melodymaker67]

So an electrician would be a good option and not a DIY job ?

 

[Taylortwocities]

It could be a DIY job, but only if you feel competent to do it.

As above, you'll need to find enough spare copper at the ends to make a good clean terminations to the shower (same goes for the switch).
Also, the instructions will tell you that you should have an RCD fitted. And you must do this, for your safety.

Installing an RCD, and testing it properly, is a job for an electrician - unless you have the relevent skills and calibrated test equipment.

EDIT
The instructions state :
"30 mA residual current device (RCD) MUST be fitted."

 

[melodymaker67]

Ok, thanks. Yes it looks like it's a bit above my head so perhaps the job of fitting an RCD as well as shower and switch could be done as an all in one. Any rough idea of typical cost ?

 

[EFLImpudence]

It doesn't look like 6mm² to me.

Smaller than the shower internal wiring.

 

[Steve]

Get a plumber and ask him/her to fit a thermostatic mixer shower. Electric showers are an awful compromise. 45amps flowing through an appliance a few inches from my wet, naked body? I don't care if there's an RCD or not. And my combi boiler has 28kw of heat available to heat the water. Why would you want a piddly little 9kw heater?

If you don't have a combi but rely on stored hot water, you can get what is known as a power shower, which pumps the stored gravity fed water to pressurise it.

 

[melodymaker67]

Well it's too late as I have already taken delivery of a new 9.5 Kw Mira shower from Screwfix earlier this week

 

[ban-all-sheds]

45amps flowing through an appliance a few inches from my wet, naked body?

What has the consumption of the shower got to do with anything?

 

[DaveHerns]

Maybe he'd rather be electrocuted by a lower current as it might be less painful

 

[ban-all-sheds]

Sometimes I think people take the "water in a hose" analogy too far...