Gainsborough Energy 2000x

[civicwalker]

On Christmas Day when one of my children had fortunately moved out of the shower spray to get some shampoo from the other end of the bath, the shower hose exploded out of the internal boiler unit in a shower of electric sparks. On entering the bathroom, I found not only a very distressed child but that water was still running from the broken shower unit into the bath and it was still live; I had to isolate the unit by pulling the ceiling switch.
Anyone any idea why the 45A fuse did not 'blow' and what, if any, additional safety features i should fit to prevent another occurence after my replacement Myra unit is fitted?
Thanks in anticipation

 

[breezer]

rcd, but its not a diy job

 

[Adam_151]

Is your shower circuit RCD protected? If not, then adding RCD protection would be a VeryGoodIdea­™

 

[civicwalker]

Thanks for the replies; the 45A box is shown on my website:
http://www.geocities.com/CIVICWALKER/diynot.JPG
I presume that I would need a 45A RCD as I have 10mm cable and the new shower is 10.8KW.

 

[Adam_151]

your shower CU only seems to have one tail and no earth to it!, I'm presuming that these are there, but just not easy to see in the photo?

And easiest thing to do would be to ditch that old fuse based shower CU and replace it with one of these: http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=102504&ts=42494&id=42858 ,shouldn't be anymore expensive than adding an RCD in a separate enclosure, and will be neater.

The other option is to have all your CUs replaced with a single modern unit, but that would be the more expensive option, as not only would all the existing circuits have to be transfered onto it, they all would have to be tested as they are being worked on.

Whatever you have done though, both main bonding and supp. bathroom bonding will have to be brought upto scratch (unless it has already been done)

 

[civicwalker]

Thanks Adam - I'll take your advise.

Meanwhile, I've uploaded a better photo to my website [same link] - can you please indicate where the "tail and earth" should be?


Thanks again

 

[Spark123]

I think he was referring to the Wylex Consumer Unit, is it fed by twin + earth?

 

[Adam_151]

Yeah, talking about on the CU, tails/meter tails ( http://www.tlc-direct.co.uk/Products/CA16TR.html ) are single core, double insulated cables used to connect consumer units to the meter, a single earth is run as well

I can see a T&E in white trunking on your first picture, I guess this is the feed to the shower, and to the right I can see what looks like a tail, if it is (and it is possible that it isn't, as suggested by spark123), is the other one hideing behind it? and I hope there is an earth there as well!

 

[civicwalker]

http://www.geocities.com/CIVICWALKER/tail.JPG

Is the above what you're referring to?

There is only one grey cable that goes to the main board?

 

[Adam_151]

can't see the pic, says you have exceeded your transfer limit.

this grey cable, is it oval shaped then (guessing if there is only one it must be T&E)

and goes into the main board? what main board is this? the main CU for the house? How is it connected there? through a fuse or are the cables just connected to the isolator terminals or something?

The correct way for it to be, would be for the tails to be split in henley blocks ( http://www.tlc-direct.co.uk/Products/RDCB6.html ), then go to both CUs

Might be worth taking a picture of the whole meter/CU area, there is a better image upload thingy here: http://imagehost.darkernet.co.uk/ , and probably the same again with the covers off the CUs (as long as you feel safe doing so - switch the main switch off, and keep your fingers away from the incomming terminals)

 

[baldelectrician]

Civic

Looking at your picture more closely it seems you have a 6mm cable feeding your shower.

I presume you will have it upgraded to 10mm.

If I were doing this job I would recommend you to replace consumer unit to a split load type (if suitable), as RCD protection for a shower is ESSENTIAL (my opinion not REGS)

Replace consumer unit
rewire shower in 10mm
upgrade any bonding as necessary
inspect test and certify

As this is a special location and you probably line in part p territory the works should be carried out by someone who is registered on one of the compotent persons schemes.

 

[grainish]

Hi civicwalker

I have just replaced a shower for a customer for the same reason.

The cause is a very iffy safety device, what happens is that the shower rose blocks up, water flow is restricted water overheats, pressure increases, BANG. The shower falls apart by design

THe tube is a tight fit into the heater unit, with an O ring then held in place by a small piece of steel

Triton showers have a similar thing but only a small ball flies out the end of the safety tube and the release of water is more controlled.


The cure fr this problem CLEAN THE SHOWER HEAD OF LIMESCALE ONCE A WEEK.

David

 

[HDRW]

http://www.geocities.com/CIVICWALKER/tail.JPG

Is the above what you're referring to?

There is only one grey cable that goes to the main board?

Yes, that's Twin&Earth going between your "Main Board" and the shower CU.

To answer a question in your original post, the 45A fuse didn't blow because the current didn't exceed 45A! A fuse only stops an overload condition, and even if the current is being shorted to Earth by the water flow, it may not pass enough to blow the fuse. That's why people recommend RCDs, because they trip in situations like the one you had.

Cheers,

Howard

 

[civicwalker]

http://www.geocities.com/CIVICWALKER/tail.JPG

Thanks for your replies - is there an 'easy way' for a novice to identify whether the gray cable is 10mm or 6mm ?

 

[Adam_151]

Two ways, one is to go on overall dimensions,

1mm² CSA T&E has overall dimensions of 7.8mm x 4.25mm
1.5mm² CSA T&E has overall dimensions of 8.2mm x 5mm
2.5mm² CSA T&E has overall dimensions of 10.3mm x 6mm
4mm² CSA T&E has overall dimensions of 11.9mm x 6.25mm
6mm² CSA T&E has overall dimensions of 13.5mm x 7mm
10mm² CSAT&E has overall dimensions of 17.1mm x 10mm
16mm² CSA T&E has overall dimensions of 19.4mm x 10mm

The other way is to look at the end of the cable:
6mm² has a 2.5mm² earth which is a single strand of copper (pic: http://www.tlc-direct.co.uk/Images/Products/size_3/CA6G.JPG )
10mm² has a 4mm² earth which is multiple strands (pic: http://www.tlc-direct.co.uk/Images/Products/size_3/CA10G.JPG )



I'm intrigued now: that piece of T&E (that I mistook for a tail from a side on view) that feeds the shower CU, where exactly does it connect on the main board?