Any experts on shower wiring?

[Concerned]

Bought a 10.5kw unit to replace old 7.5kw. Replaced 6mm cable run with 10mm then got a spark in yesterday wire it all up.
I have a couple of concerns about the work he did and would appreciate any advice.
1) 10mm runs from shower to 50a pull switch to 40a RCD, but the spark did not replaced the old 2 inch long 6mm cable between the RCD and the power switch. Will this be ok?
I feel that the run is from the power switch to the shower and this 2inch piece is effectively creating a weak link in the run, and the fact that it is on the power side of the RCD means that if there was a problem the RCD would not trip. Am i right to be concerned.
2) The old shower had an additional 2 earth cables attached to the unit as well as the twin and earth. Not sure where these go. The spark has not used any of these and has only used the earth in the 10mm cable. Should the new setup use the same amount of earths as the old?

One top of this the shower does not work properly. The old shower had plenty of power/pressure but was a little cold in winter hence the upgrade. The new unit has power to it and the water is turned on as before but all we get is a trickle of water through the hose and there is no heat in it at all. We did switch it on initially with the sprayhead attached but I'm sure the PRD did not blow as there is not any water coming out of it. Sprayhead now removed but flow pressure is terrible. Just removed the unit from the wall and water supply and turned the water on, it hit the ceiling so I don't think the ingoing pressure is a problem.

If anyone can help with any of this I would appreciate any advice and comments

Thanks

Graham

 

[baldelectrician]

What make is the shower?

You have to comission some showers in such a way as to stop element heating until the tank fills up completely

There should be bonding cables connected- assuming there are not plastic pipes everywhere including radiator.

Has the pipework been flushed out prior to fitting the shower.

If you are in a tenement flat the cold may be tank fed, which may cause shower to fail to heat. You need a fair bit of pressure to get a 10kw shower to kick in.

 

[Concerned]

What make is the shower?

You have to comission some showers in such a way as to stop element heating until the tank fills up completely

There should be bonding cables connected- assuming there are not plastic pipes everywhere including radiator.

Has the pipework been flushed out prior to fitting the shower.

If you are in a tenement flat the cold may be tank fed, which may cause shower to fail to heat. You need a fair bit of pressure to get a 10kw shower to kick in.

Thanks for this. I think it had been the way it was comissioned. I've spent the afternoon dismantling emptying and cleaning the whole setup and recomissioning step by step with the book and it worked!!! Only thing is i'm still a little scared to use it...
I think, as you say, there should be bonding around the bathroom. I checked the 2 earths that were on the last shower unit but this guy didn't use. One goes under the bath, the other onto the cold water supply for the shower. I think by not connecting these up the bonding circuit in the bathroom is broken
I'm no electrician but from what I've read inline today i'm really not sure if this setup is safe..anyone know for sure??

 

[Igorian]

WRT the shower operation, there is usually a setup procedure to a) prime it with water and b) to acclimatise it to the installation location. The procedure is generally quite simple and should be explained in the manual.

Edit... oops too late.

 

[Steve]

1) 10mm runs from shower to 50a pull switch to 40a RCD, but the spark did not replaced the old 2 inch long 6mm cable between the RCD and the power switch. Will this be ok?
I feel that the run is from the power switch to the shower and this 2inch piece is effectively creating a weak link in the run, and the fact that it is on the power side of the RCD means that if there was a problem the RCD would not trip. Am i right to be concerned.

yes. However, wrong reasons for concern. The RCD will trip in the event of an earth fault regardless of what cable it is wired in. The 6mm² will get hot. You should change it asap, as any slightly loose connections (secure connections can become loose over time) will cause it to melt and possibly create a short, causing the MCB / protective device to operate.

What is this "power switch" you speak of?

Also, the 40A RCD is underrated and will also run hot, you need a 63A one with 30mA protection, with a 50A MCB in the chain somewhere.

 

[Spark123]

Also sounds like he has disconnected the supplementary bonding in the bathroom. Best get it checked out by another electrician.

 

[kai]

This appears to be a badly botched Part P Notifinable job - stop using it and get it re-checked by a qualified professional.

 

[Spark123]

Scotland is not covered under Part P, I believe they have building warrants which are worse, just as well I don't venture north or the border

 

[baldelectrician]

Put this up on my website, you can print it off or expand it on the screen.


http://www.baldelectrician.com/host/metalpipebond.pdf

 

[Concerned]

1) 10mm runs from shower to 50a pull switch to 40a RCD, but the spark did not replace the old 2 inch long 6mm cable between the RCD and the power switch. Will this be ok?
I feel that the run is from the power switch to the shower and this 2inch piece is effectively creating a weak link in the run, and the fact that it is on the power side of the RCD means that if there was a problem the RCD would not trip. Am i right to be concerned.

yes. However, wrong reasons for concern. The RCD will trip in the event of an earth fault regardless of what cable it is wired in. The 6mm² will get hot. You should change it asap, as any slightly loose connections (secure connections can become loose over time) will cause it to melt and possibly create a short, causing the MCB / protective device to operate.

What is this "power switch" you speak of?

Also, the 40A RCD is underrated and will also run hot, you need a 63A one with 30mA protection, with a 50A MCB in the chain somewhere.

Thanks for all the replies, very helpful since i know nothin about electrics. I will get this guy back to explain why he did it this way, then get someone else to check it all out.

Hope the link to the photo works (after a few tries it appears it doesn't...to see the photo right click the red X and select 'properties' then copy and paste the address shown into the address bar to see it)... it shows the power switch on the left just above the RCD, the 2inch cable i talked about connects these. The power switch is connected directly by 2 cables to what i would call the meter, I assume this is the mains supply from outside the house because the meter also has 2 cables connecting it to the fuse box. This is why i was concerned about the short cable melting as i cannot see another cut-out between it and the mains.

This is the RCD and is rated to trip at 30mA as you suggest but is only 40A, from what you say i should be looking to upgrade this to min 63A?

Unless I am interpreting my whole setup wrongly, very possible as I know nothin about electrics, but i do not see another trip device in the chain. Should I be installing an MCB between the power switch and the meter?

Spark123 thanks for confirming my fears about the bonding in the bathroom. I knew nothin about bonding until i started reading today. It just seemed strange that the previous setup of bath to shower unit to cold supply was now bath to nothing and nothin to cold water supply.

Is my setup as old and dangerous as it is seeming to appear to me???

Cheers

Graham

 

[ban-all-sheds]

Photos not working. You need to read the instructions for that website on how to use hotlinking to the photos or thumbnails.

The power switch is connected directly by 2 cables to what i would call the meter, I assume this is the mains supply from outside the house because the meter also has 2 cables connecting it to the fuse box. This is why i was concerned about the short cable melting as i cannot see another cut-out between it and the mains.

That sounds very alarming. Hope it's not what it sounds.

Need the photos....

 

[Concerned]

Photos not working. You need to read the instructions for that website on how to use hotlinking to the photos or thumbnails.

The power switch is connected directly by 2 cables to what i would call the meter, I assume this is the mains supply from outside the house because the meter also has 2 cables connecting it to the fuse box. This is why i was concerned about the short cable melting as i cannot see another cut-out between it and the mains.

That sounds very alarming. Hope it's not what it sounds.

Need the photos....

working on a direct link but amended previous post to explain how to see photo, i added (after a few tries it appears it doesn't...to see the photo right click the red X and select 'properties' then copy and paste the address shown into the address bar to see it)...
sorry but i can't find another way to show photos from this site.

Thanks for diagram baldelectrician it is what i found while browsing earlier and alerted me to the lack of bonding between the shower unit and the cold supply.

 

[Concerned]

Just checked, the power switch has a 30amp fuse in it, personally don't know if thats good or bad, find out after work tomorrow i guess, thanks all.

 

[ban-all-sheds]

working on a direct link but amended previous post to explain how to see photo, i added (after a few tries it appears it doesn't...to see the photo right click the red X and select 'properties' then copy and paste the address shown into the address bar to see it)...

OK - that works, but a bit inconvenient for people..

sorry but i can't find another way to show photos from this site.

Use another hosting website
or
see what the instructions for that one say about hotlinking - you were not pasting the URL of the actual image between the [img] [/img] tags - I guess it was the URL of some sort of script that displays the image. For it to work here in-line you need [img]URL of the actual image file[/img]

But they've done something to that site to prevent that, as these:

still don't work. You need to find out what they need you to do, or use a site that isn't so precious about hotlinking.

Just checked, the power switch has a 30amp fuse in it, personally don't know if thats good or bad, find out after work tomorrow i guess, thanks all.

Bad.

10.5kW shower.

10500 ÷ 240 = 43.75A.

So as well as getting the RCD replaced, you need a bigger fuse in that switch. You need to get the electrician back and get him to sort it properly this time.

Probably the best solution is to lose the separate RCD & switchfuse, and install a small CU (may be able to re-use that existing RCD enclosure) with an MCB and RCD. So at that time that little bit of 6mm² will go.

 

[baldelectrician]

Concerned

Looks a mess, the preferable option would be to rip out old wylex consumer unit- grey metal large one, and repace it and the shower unit with a split load 10 or 12 way consumer unit.

makes things a lot neater and safer.