storage heaters protection

[SparkyTris]

Considering the replacement of a cartridge-fuse type fusebox which is protecting a houseload of storage heaters. One of these is a traditional wall-mounted brick-filled heater, another is an immersion element, the others are underfloor mat-embedded-in-screed heaters.

MCB's or RCD+MCB's or RCBO's?

What might be the drawbacks of protecting each circuit with its own RCBO? (other than cost)

 

[EFLImpudence]

It's up to you. Why do you want to change the fuse box?

 

[SparkyTris]

I want to change it because:

the front cover of the existing box is physically damaged.
I think the installation will be safer with residual current protection in addition to overcurrent protection. (I am prepared to be disabused of this potentially erroneous belief)
avoid the inconvenience of cart fuses (Im not intending to use these as everyday switches, but it is convenient to shut off heating to certain areas at the fusebox on a seasonal basis)

 

[SparkyTris]

anywhere that electricity is used to heat domestic hot water somehow gives me the willies.
I understand that immersion heater elements are intrinsically earthed on their outer jacket, and the incidence of people receiving electric shocks through their DHW is effectively nil. However, the physical proximity of the Line conductor to water (a few millimetres in the case of an immersion heater) is what scares me.
This does not scare me sufficiently to not use electric showers, but ....
it does seem like a nice idea to have an RCD on any cct involved with water & naked flesh. kinda seems like what they were invented for.

 

[EFLImpudence]

Fair enough if it is damaged.

As a new consumer unit will have to have RCDs then RCBOs would be the ideal.



I cannot disabuse you but it is not necessarily the line conductor and water proximity that is generally a safety problem but where a line conductor contacts wet people, although, as you say, it is extremely rare. It is far more hazardous going to work and having accidents in the home.

 

[SparkyTris]

Is there any good reason not to specify a metal fusebox? (apart from cost)
Why would the new CU have to have RCDs?

 

[EFLImpudence]

Is there any good reason not to specify a metal fusebox? (apart from cost)

You won't be able to do anything else.
CUs must now be non-combustible and steel is virtually (or literally) the only option available.

Why would the new CU have to have RCDs?

New work must comply with the latest regulations.

I thought that was what you wanted.

 

[ban-all-sheds]

This does not scare me sufficiently to not use electric showers

Kettles?

Taps connected by copper pipes to copper cylinders with electric heating elements in?

kinda seems like what they were invented for.

Not really.


You should find a way to be not scared of things which heat water electrically - being scared all the time will shorten your life.

 

[SparkyTris]

Kettles?

Taps connected by copper pipes to copper cylinders with electric heating elements in?

Sure, sure - but I don't usually get into the kettle naked.
taps-pipes-DHW bottle + immersion, sure, but washing your hands, you feel less vulnerable than in the bath or shower.

Don't get me wrong - this is an irrational consideration, and not one which causes any actual fear. Or mitigating actions such as showering in full PVC suits or pentagrams on the bathroom floor.

it probably stems from (back in the distant past when I first dismantled an electric shower) at being somewhat alarmed by the very close proximity of fat line conductors with practically unlimited current being separated from a naked wet person by a few millimetres of plastic. and then the realisation that the water spraying over you was heated by that conductor about 3 feet of hose away. And the general appearance of cheapness and crapness that you see inside an electric shower. (despite their external glossy appearance)

But they are obviously safe. it's the same fear that about 95% of us have when taking off in a jet airplane. you don't think twice about crossing the road but you can't help thinking of fireballs when flying. In spite of the fact that crossing the road is demonstrably about 100% more dangerous.
If only we could all be as rational as a 6502, eh?

is it now regulatory law to have RCD protection on all finals? which regulation states that?

whilst we're at it,

old (1940s-1960s) fuseboards that I have seen had 2 screw terminals on most of the current carrying conductors. current (domestic) equipment never has this. they only ever have one screw terminal on everything.
why is this?

 

[ban-all-sheds]

showering in full PVC suits

Oh go on - you know you want to...

fat line conductors with practically unlimited current

What on earth has that got to do with it?

it's the same fear that about 95% of us have when taking off in a jet airplane.

Count me in the 5% then.

you can't help thinking of fireballs when flying

Never enters my head - why should it?

In spite of the fact that crossing the road is demonstrably about 100% more dangerous.

It's probably demonstrably much more more dangerous than that.

is it now regulatory law to have RCD protection on all finals? which regulation states that?

Not quite all, but in combination with other situations which trigger a requirement for RCDs it might as well be. But the regulations are not law.

I'm seriously wondering about your user name. I know you'll probably say that "sparky" means all sorts of things, but quite honestly, to use it on an electrical forum if you are not an electrician is at best foolish, at worst disingenuous.

old (1940s-1960s) fuseboards that I have seen had 2 screw terminals on most of the current carrying conductors. current (domestic) equipment never has this. they only ever have one screw terminal on everything.
why is this?

It's cheaper.

 

[SparkyTris]

I'm seriously wondering about your user name.

You are absolutely right, it was thoroughly ill-chosen, I apologise for the energy and time you have wasted in seriously wondering; and for the chagrin it occasionally causes you. Please, can I change it?

 

[SparkyTris]

Well, shiver me timbers. I just have.

 

[sparkwright]

.

 

[ban-all-sheds]

Well, shiver me timbers. I just have.

Good.

 

[Lectrician]

anywhere that electricity is used to heat domestic hot water somehow gives me the willies.
I understand that immersion heater elements are intrinsically earthed on their outer jacket, and the incidence of people receiving electric shocks through their DHW is effectively nil. However, the physical proximity of the Line conductor to water (a few millimetres in the case of an immersion heater) is what scares me.
This does not scare me sufficiently to not use electric showers, but ....
it does seem like a nice idea to have an RCD on any cct involved with water & naked flesh. kinda seems like what they were invented for.

The embedded floor heating would warrant RCD protection more than the immersion.

I would opt for RCBOs if the circuits must be RCD protected. Heating loads by their nature can be a little leaky, so more prone to nuisance tripping.