Electric shower temperature fluctuating

[Subby]

Hi all plumber here...
My customer complained about fluctuating temperature at the electric shower so I removed the said shower and replaced with a new one.
They still have the problem, and a neighbour has suggested it may be "something to do with the fuse box"
Is it possible that this could be an electrical fault somewhere?
The rcd is fourth from the left (next to the one labelled rcd circuits) the shower is 9.5kw. Nothing trips out.
Thanks in advance.
I tried to upload a picture of inside the consumer unit, the live wire to the shower looks to be about 8 mm diameter and the shower is about 4 metres away from the rcd.

 

[Subby]

Here is the picture. The shower is the fourth from the left

 

[Subby]

MTN140

 

[Subby]

Is there possibly is a fault I will advise them to get the electrician in I just don't want them to call somebody in if it is un necessary

 

[Rpa07]

If it’s an intelligent shower it may be water pressure making the safety come on and off. I had one the other day that would go cold and show LP (low pressure) at 0.7 bar. We got in touch with the water supplier to check mains pressure in. Not concluded yet but also haven’t heard anything.

 

[Richard Burns]

A fluctuating temperature either means the temperature of the incoming water is varying a lot, which is only likely if the cold pipes are run in contact with hot pipes, an under pressure cut out, but only if the shower changes in flow as well as temperature, or that there is an intermittent loss of power to the elements, this is usually caused by an overheating connection. Most commonly this occurs in the shower isolator switch, but may also occur in the consumer unit, not on the line as shown in your picture, but possibly the neutral.

 

[DPG]

Can't imagine the incoming water temperature to be varying wildly enough to cause this.

As Richard says above, could be poor connection somewhere. Check all connections are made correctly and are tight enough - from the MCB, through the isolator and at the shower. Maybe an old isolator switch which has gone a bit 'high resistance' at its contacts?

Another thought - do they see slight varations in brightness of lights in the house? Could be supply issue?

 

[Rpa07]

Bristol water only allow for 1 bar pressure at the incoming meter. That’s not a lot of pressure and when the street on that main are on and off with their demand it could be giving an up and down slight of pressure. Just realised you’re a plumber and you know that! Sorry wet pants!
Have you checked water pressure in? out of interest.

 

[telectrix]

we get that all the time. every time someone flushes the bog, the shower goes cold.

 

[DPG]

we get that all the time. every time someone flushes the bog, the shower goes cold.

That's all you want - someone on the lav while you're having a nice shower.

 

[shaun1]

Are you able to replicate the fault? You may then be able to see if the preasure is dropping or the power cutting out. Is there a light or indicator on the shower to show it has power? This may flicker or go off if there is a fault with the supply.

As others have said, check all connections to make sure they are tight, and look for signs of heating or arcing at the terminals. It may be better to get an electrican to do this part.

 

[Squid]

*Faints,

The forum helping a plumber out..............

Just kidding ;o)))))

 

[Rpa07]

*Faints,

The forum helping a plumber out..............

Just kidding ;o)))))

It was in the small print - we didn’t pick up on it straight away!

 

[Squid]

Not the "sharpest" tools in the box then......... ;o))))

 

[Rpa07]

You weren’t there man!

 

[Dave-geo]

Make sure they haven't set the temperature too high. Most showers have a thermal cut out that turns off the elements when the temperature reaches 47 degrees. If the temperature is set too high the unit will cycle hot and cold. When it goes cold the obvious thing to do is turn the temperature up which only makes matters worse.

 

[Dave OCD]

I'd say there's a fair chance it's the pull switch on the way out, if you look inside [with power isolated] you may see signs of overheating on one or more of the cable cores near where they terminate in the switch. A fairly common problem caused by poor installation or carp switches that aren't really up to the load that runs through them.