Identify shower cable

[Cocat2517]

Hi
I'm refurbing a couple of ensuites, want to replace the electric showers (one 7kw and one 8.5kw) with new ones, either 9.5kw or 10.8kw.

Can anyone help identify if the current mains cable is big enough to handle the extra load? The cable measures approx 12mm across flat side. I held a smaller cable up for comparison, that cable was about 9mm across.

A few pics below, including the rcd.

Thanks

 

[flameport]

Not possible to accurately identify the size from the pictures, but given that it's smaller than the wires inside the shower, it it very likely undersized.
Are the wires solid core or several individual strands of wire?

Both circuits are 32A, which is OK for a 7kW shower.
An 8.5kW shower is over 35A, so that is already wrong.
9.5kW requires a 40A circuit, and 10.8 at least a 45A.
As you have 2 electric showers and a cooker circuit on what appears to be an 80A RCD, it's already in danger of being overloaded. Increasing the rating of the showers makes this far worse.

A lot more investigation and work will be required here.

 

[AndyPRK]

Look like 6mm to me.
It has strands.

 

[EFLImpudence]

Look like 6mm to me.
It has strands.

So has 4mm²

Do you think the shower internal wiring is 10?


https://www.diynot.com/wiki/Electrics:flatpvccables

 

[AndyPRK]

Humm I guess it could be 4mm.
I hadn’t considered anyone would be stupid enough to install 4mm for a shower

It certainly can’t be described as big!

 

[Cocat2517]

Thanks for the replies, looks like I'm getting someone in.

With the consumer unit... do I need to replace the entire unit? Or can I just replace the 80a main switch to something bigger, then replace the two shower rcds with 45a ones?

It's for a 10 person holiday let property, ideally I want it safe for guests to use both showers and cooker and a few minor appliances.

I'll get the rcd sorted, get 10mm cable installed to the showers then upgrade them. I'll stop using the 8.5kw for now just to be safe.

 

[flameport]

The real question is what size of supply does the property have.
60A or 80A would be common, perhaps 100A in a few cases.

Two electric showers and a cooker is usually a fail in most properties, unless other solutions are installed such as devices to prevent both showers being used at the same time.
How is the property heated - other types of shower would be a better solution than electric ones.

 

[Cocat2517]

It's 4 bed detached house, solid stone walls.
Heating & hot water via LPG combi boiler (37cdi), radiators. Two bathrooms and one ensuite.

The plan was to have two electric showers and a third shower from the combi boiler supply. I'm thinking ditch an electric shower though and just have two showers (1 electric 1 combi)

I think possibly it's 100a supply? I've attached more photos of the units.

It seems the unit is incorrectly labelled too. Where it says "cooker" I think this is no longer the case. In the first photo that shows a unit by itself with a 63a rcd (labelled EUR1), that's the cooker. I tested it by switching this off, the cooker went off, but switching off the 32a labelled cooker did nothing.

With that in mind can I out a 45a rcd in the unit for a 10.8kw shower? Everything else on it is just lights & sockets.

 

[terryplumb]

You should also check your water pressure is good enough . with ten people ,two bathrooms and an en suite,
Any combination of the two showers you are thinking of ,electric or combi ,
May not work simultaneously. Is all of your plumbing connected to the mains ,no stored water ?

 

[ban-all-sheds]

With that in mind can I out a 45a rcd in the unit for a 10.8kw shower? Everything else on it is just lights & sockets.

You must, must, must get an electrician to do absolutely everything.

 

[Cocat2517]

You must, must, must get an electrician to do absolutely everything.

I absolutely will be. I can swap a shower like for like, but anything else, no. I'll be getting someone in to do any work that needs doing.

Regarding water pressure, will check it out. Yes, all connected to mains, no stored water.

What's the easiest way of checking for pressure to get an idea of what it is?

 

[terryplumb]

Static pressure and dynamic pressure are two different things that you need to establish ,together with flow rates. You can only measure pressures with a pressure gauge .you can buy a cheap one that screws onto an outside tap.you should start another thread in the plumbing forum ,save this one going way off topic.

 

[Cocat2517]

Thanks, will do.

If someone can let me know regarding my supply for the property, is it 100a?

If the cooker is on that separate 63a unit what does that mean for the main unit?

 

[securespark]

I hadn’t considered anyone would be stupid enough to install 4mm for a shower

In the earlier days of showers, 4 milli was very commonly installed for showers. The leccy boards used it for 6-7kW units.

 

[EFLImpudence]

Can't tell. The 100A on the label is the maximum rating of the housing.

It could have any fuse inside 60, 80 or 100.



I know it's silly but the supplier doesn't care about you nor us.