Shower keeps tripping off

[holman210]

Hi

My shower keeps tripping off at the Consumer box. It does not do it straight away only when the shower has been on for a while (Approx 10mins) but it is random so its sometimes longer. Happens quicker the hotter I have the water. I dont remember it happening when the shower first went in. Seems to be happening more and more frequently.

I had a 8.5kw shower, which I replaced with a Triton Bezique 9.5kw. I believe the cable is a 6mm (how can i double check this?)

Cable lenght is approx 38ft long, Fuse box to shower.
I have a switch along this cable between the consumer box and shower.
On the consumer box (See photo) there is a fuse which the shower is wired into. On the side it reads " 240v - CaL Temp 20degrees - Type B - 5A M1 - 15A-45A M2" On the red button that pops out when shower has tripped it says "30a"

I have not changed anything but the shower, just took the old one off and put the new one on. I thought it would be fine as I read on the net that a 9.5kw shower is ok on 6mm cable. Is there a chance the fuse is faultly? My electric cupboard is very old but never had any problems with the old shower. Although sometimes if the kettle, washing machine and tv are all on at the same time the plugs trip off in the consumer box. Must be overloading which could be happenening to the shower?!

Thanks!

 

[oharaf]

Grim news old boy.

9.5Kw = 9500w 9500/230 = 41 amps - That fuse of 30A is way to small

6mm cable not up to carrying those sorts of currents either, you need 10mm

Sorry

 

[Taylortwocities]

And that old fuseboard has a max rating of 30 amps per position so dont think of upping the fuse!
Have you got RCD protection on the shower circuit. I cant see one from the photo.

You're going to need to change the cable to 10mm and install a mini board that has the correct protection device and and RCD.

You could think about changing the shower for one that has the same capacity as the old one....

All of the above is notifiable work....

 

[holman210]

No I dont think there is a RCD

So without having to change cables and other bits Im going to need a 8.5kw shower. Thats not so bad I got the new shower free so buying another isnt a problem.

Will a 8.5kw shower be ok on 6mm cable and 30A?

How can I check the cable size? Do you just measure the width across the cable?

Thank you very much for your help

 

[oharaf]

Sorry Forgot to mention about the RCD protection

The board itself looks rather 'tired' that 16A fuse looks to be a bit 'wobbly' as well.

I would even consider having a new board.

Where in the land are you?

 

[BS3036]

Will a 8.5kw shower be ok on 6mm cable and 30A?

30A x 230V = 6.9kW max

You can't allow for diversity with a shower.

So no, not really. In practice the fuse will stand some overload, but it's not a good situation.

 

[holman210]

I was thinking that as it goes. It looks like a right mess with lots of DIY goings on before I moved here.

I have always been concerned about the 16A fuse but I had always planned to get the cupboard brought up to date but never get around to sorting it. That one also trips off, due to (I think) having all the plugs in my flat on that one fuse.

Im in sittingboure kent. What sort of price am I going to be looking at to get it replaced? It looks like quite a big job as everything but the heating CB is old.

Thanks!

 

[oharaf]

Christ what a mess!!

Well for CU and tails and bonding (if they need upgrading) I would say you're looking at £150 for accessories then it depends on just how much work is to be done, and you're down south so probably a bit more pricey than up here in gods own.

I would expect £350 upward, hard to tell from a picture.

Once the CU is installed the sparks will have to carryout a full test of the installation before certification.

Get some reccomendations from people you know, get 3 or 4 quotes

 

[holman210]

I got a quote to have my box replaced. He said £325 but he has not seen it yet!

I was looking at a new shower, on the box it says:

8.5kw (Nominal) 240v AC - 7.8kw (Nominal) 230v AC

What does that mean? I have a 6mm cable so Im looking for under 8kw can you get these? Although on the box of a 8.5kw shower it says "Minimum cable size 6mm, reccomended 10mm" So that would mean that a 8.5kw is ok on 6mm?

Thanks!

 

[ricicle]

I got a quote to have my box replaced. He said £325 but he has not seen it yet!

Don't even consider using him then - stay well clear!

 

[333rocky333]

what does it say on the label beneath the main switch on the wylex Consumer Unit

 

[holman210]

Hi

It says, "Total Load not to exceed 60Amps, 240v AC 50Hz"


Why not to use him? Does it sound too cheap or expsensive?

Thanks

 

[333rocky333]

60 amps is the total load on the whole board

The reason TTC said earlier, you should not fit a 45 amp fuse/mcb in that board.
Even though one is available to fit a similar board that has a 100 amp mainswitch

Therefore even if you changed the cable, it would not be wise to connect to that board, as with the sockets, lights on, etc, you could overload the board

 

[holman210]

No thats right I woulnt change any MCB's only exact replacments. The total MCB's equal to 100amps so no wonder its tripping off. It amazing that this board has lasted this long.

Thanks

 

[Taylortwocities]

You dont add up the MCB values to find the total demand.
Its more complicated than that.
I all works on the principle that no circuit will be working at anything like full load.