storage heaters protection

[Echo the husky]

However, the physical proximity of the Line conductor to water (a few millimetres in the case of an immersion heater) is what scares me.

Dolphin showers used heaters with an uninsulated element and flow switches directly immersed in the water. As do the cheap heated shower head type showers.

 

[JohnD]

uninsulated?

you mean like this?

Fancy that.

 

[Echo the husky]

Electrically un-insulated.

 

[ban-all-sheds]

OK, so....

Dolphin showers used heaters with an uninsulated element

Which part(s) of the heater were electrically uninsulated from which other part(s)?

 

[Echo the husky]

The element being uninsulated from the water.

 

[ban-all-sheds]

I can't tell from that photo what relevant information I am supposed to glean.

Can you explain exactly what you mean by "the element being uninsulated from the water"? The only thing I can think that that logically could mean is some sort of electrode heating, but it cannot be that, so what does it mean?

 

[Echo the husky]

If you look carefully at the bottom of the plastic heater unit you can just make out the bare spiral heater element wire is directly in the water it is heating, as are the flow switch contacts that are at the top of the heater unit.

 

[ban-all-sheds]

I very much doubt it.

What's this:

?

 

[Echo the husky]

What's what?

 

[ban-all-sheds]

That part of the shower.

The part that looks like a heater can for an electric shower.

 

[Echo the husky]

Yes one of the elements can be seen through the clear plastic below the metal clip.

 

[ban-all-sheds]

Well, unless we can find a shower to dismantle, or a good manual with an exploded parts diagram, I'm going to have to go with the conclusion that your theory of shower water flowing over a piece of wire at 230V to earth is so preposterous that it has to be disregarded, and that you are misinterpreting what is in the photo.

 

[Echo the husky]

I have worked on enough Dolphin showers now to know that is true, that's why the internal pipework is so long, and the inlet and outlet connectors are earthed metal.

Rather less safe versions are available:

 

[ban-all-sheds]

I have worked on enough Dolphin showers now to know that is true,

Maybe your misinterpretation is long established.

that's why the internal pipework is so long, and the inlet and outlet connectors are earthed metal.

Long enough so that there's never more than a few mA of earth leakage?

Sorry, Echo - whilst it is true that I do not have wide experience of electric showers, I've never heard of any domestic water heating appliance being made like that, and I cannot imagine any advantage of doing it, but I can see enough safety and reliability issues to mean that it would be madness.

The problem is that I can't see what you are suggesting in the photo, and what you are suggesting is barking mad.

 

[Lectrician]

Those dolphin showers did have the scary wire coil in water. Madness. Long discontinued. Came across one in an old pet groomers a while ago.