To RCD protect or not to RCD protect (a hopefully simple question)?


U

usenet

Wheelbarrowbob said:
I agree with you, as far as i am aware the UK ( possibly Australia ) is the
only country to have fused 13A plug tops on a 32A ring. If i did a self build
etc i would have each room on its own 20A radial ( kitchem 32A ring). in the
event of a fault makes tracing it easier, easy life !
All the major additions I have done to our wiring have been radials.
I've kept the two existing rings but our studies (full of computers
etc.) have their own 20 amp radials, as does the utility room.
 
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M

Martin Angove

In message <[email protected]>,
Z said:
16A breaker 2.5mm cable or 1.5
Pirelli terminating in a switched fused spur with /without neon as per
your preference.
Umm... can you enlighten me why Pirelli cable should be so much better
rated than ordinary? The only thing I can think of is that you are
referring to MICS cable...?

Hwyl!

M.
 
B

BigWallop

Martin Angove said:
In message <[email protected]>,


Umm... can you enlighten me why Pirelli cable should be so much better
rated than ordinary? The only thing I can think of is that you are
referring to MICS cable...?

Hwyl!

M.
Or LSF (low smoke and fumes) or Flame Shielded cable (commonly used in the installation of
fire alarms).


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L

Lobster

No, the only sockets\fittings that need RCD protection are ones that
are likely to supply portable equipment used outdoors. It has the same
pros and cons as the freezer, you don't lose heating or hat water if
the RCD trips.
Really, is that right? I was under the impression that having RCD
protection was for added general safety in the home, is that not
right? Are you saying that, for example, in a non-ground-floor flat
(where there is a zero likelihood of using portable equipment
outdoors) it is pointless spending the extra on installing an
RCD-protected consumer unit?

David
 
G

G&M

Lurch said:
The regs say DP.
Agreed - but I do wonder if the regs have lost the plot here.
You should never ever under any circumstances even contemplate placing
a switch in the earth\cpc cable.
Then why can you buy 3 pole switches with one pole marked "E" ?
 
G

G&M

G&M said:
Then why can you buy 3 pole switches with one pole marked "E" ?
Decided to check myself and these are used for fan isolation. Quite why
these are OK to switch the earth is another mystery of course.
 
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A

ARWadsworth

G&M said:
Decided to check myself and these are used for fan isolation. Quite why
these are OK to switch the earth is another mystery of course.
Usually they switch L1, L2 and N.

Adam
 
L

Lurch

Really, is that right?
Yep, certainly is.
I was under the impression that having RCD
protection was for added general safety in the home, is that not
right?
No, and yes. An RCD does offer additional safety but isn't required
unless you're likely to be running power outdoors from the sockets in
question. Obviously in the case of a shower it is highly unlikely that
it will somehow become 'portable' and 'outdoors'!
Are you saying that, for example, in a non-ground-floor flat
(where there is a zero likelihood of using portable equipment
outdoors) it is pointless spending the extra on installing an
RCD-protected consumer unit?
Well, not pointless as such, it does offer additional protection, a
common misconception, held by quite a few electricians too!
An RCD isn't 'required' in such circumstances. At my house I have some
of the downstairs sockets on an RCD but as most of the outside has a
socket conveniently located somewhere nearby it's not really
neccesary.
 
L

Lurch

Then why can you buy 3 pole switches with one pole marked "E" ?
You can't, you must be looking at it wrong. Fan switches are for L,
Switched L, and N. The E is meant to be continuous throughout, with no
switches. Have another good look at your switch.
 
O

Owain

"G&M wrote
| > Then why can you buy 3 pole switches with one pole marked "E" ?
| Decided to check myself and these are used for fan isolation.
| Quite why these are OK to switch the earth is another mystery
| of course.

Fan isolators are 3 pole because they switch
- permanent live
- switched live / trigger
- neutral

on fans that have a timer over-run trigged from the lightswitch.

They should *not* switch the earth, and I don't know why one pole is
labelled E. It's extremely misleading and irresponsible IMHO.

Owain
 
G

G&M

Owain said:
"G&M wrote
| > Then why can you buy 3 pole switches with one pole marked "E" ?
| Decided to check myself and these are used for fan isolation.
| Quite why these are OK to switch the earth is another mystery
| of course.

Fan isolators are 3 pole because they switch
- permanent live
- switched live / trigger
- neutral

on fans that have a timer over-run trigged from the lightswitch.

They should *not* switch the earth, and I don't know why one pole is
labelled E. It's extremely misleading and irresponsible IMHO.
Well that's identified that the switch I have *isn't* a fan switch.

WTF it is though I'm not sure but having just checked with a meter it
definitely switches the connection from E to Eload as well as L to Lload and
N to Nload. It's a standard looking switch with no neon, front lead
connection or fuse. Any suggestions ? (other than bin it :)
 
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L

Lurch

Well that's identified that the switch I have *isn't* a fan switch.

WTF it is though I'm not sure but having just checked with a meter it
definitely switches the connection from E to Eload as well as L to Lload and
N to Nload. It's a standard looking switch with no neon, front lead
connection or fuse. Any suggestions ? (other than bin it :)
Well. you've baffled me! Is it definitely for the UK market?
 
G

G&M

Lurch said:
Well. you've baffled me! Is it definitely for the UK market?
Looks like a standard MKS 'clone' and I don't tend to buy electrical
fittings while abroad. But it might have come from some strip-out or other.
Unless there's a gallery of horrors somewhere I think this goes in the bin
in case somebody uses it.
 
Z

Z

Lobster said:
(e-mail address removed) (Lurch) wrote in message


Really, is that right? I was under the impression that having RCD
protection was for added general safety in the home, is that not
right?
Absolutely. Minimum requirements are exactly what they are- minimum
requirements.
Are you saying that, for example, in a non-ground-floor flat
(where there is a zero
Zero? you'd be surprised what I have seen being lowered out of upper
levels of multis.
likelihood of using portable equipment
outdoors) it is pointless spending the extra on installing an
RCD-protected consumer unit?
RCD protected consumer units are a waste of time IMO. RCBOs are getting
a lot cheaper.
 
M

Martin Angove

In message <[email protected]>,
BigWallop said:
Or LSF (low smoke and fumes) or Flame Shielded cable (commonly used in
the installation of fire alarms).
Now you've confused me >:-/

My problem was with "Z" who was apparently saying that whereas you'd
normally use 2.5mm cable on a 16A circuit, if it were Pirelli cable then
1.5mm is sufficient. TBH 1.5mm T&E should be ok for 20A under method 1
whatever the manufacturer.

I threw MICS in because I am aware (Table 4J1A) that it has a somewhat
higher current-carrying capacity than 70C PVC T&E and wondered if he
had been confused. I might go so far as to allow 90C cables a higher
capacity (more tables)... but there are plenty of manufacturers other
than Pirelli producing those :)

Isn't LSF cable rated exactly the same as PVC of similar construction?
Never used your Flame Shielded stuff, though I have seen it, but I can't find
it in the regs either. Does it come under MICS?

Hwyl!

M.
 
B

BigWallop

Martin Angove said:
In message <[email protected]>,


Now you've confused me >:-/

My problem was with "Z" who was apparently saying that whereas you'd
normally use 2.5mm cable on a 16A circuit, if it were Pirelli cable then
1.5mm is sufficient. TBH 1.5mm T&E should be ok for 20A under method 1
whatever the manufacturer.

I threw MICS in because I am aware (Table 4J1A) that it has a somewhat
higher current-carrying capacity than 70C PVC T&E and wondered if he
had been confused. I might go so far as to allow 90C cables a higher
capacity (more tables)... but there are plenty of manufacturers other
than Pirelli producing those :)

Isn't LSF cable rated exactly the same as PVC of similar construction?
Never used your Flame Shielded stuff, though I have seen it, but I can't find
it in the regs either. Does it come under MICS?

Hwyl!

M.
You're actually better treating the cables as being the same as PVC T&E Martin.
For safety sake on the circuits you're designing anyway, it's best to use the
tables for the plain T&E cables.
 
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Z

Z

Martin Angove said:
What does that mean?
Now you've confused me >:-/

My problem was with "Z" who was apparently saying that whereas you'd
normally use 2.5mm cable on a 16A circuit, if it were Pirelli cable then
1.5mm is sufficient. TBH 1.5mm T&E should be ok for 20A under method 1
whatever the manufacturer.
In the trade Pirelli refers to cable of a fire retardant nature such as
FP200/gold, Fire-tuf, fire-tec and their ilk.
I threw MICS
Mineral Insulated (MICC) you mean?
in because I am aware (Table 4J1A) that it has a somewhat
higher current-carrying capacity than 70C PVC T&E and wondered if he
had been confused.
No, I'm not confused.
I might go so far as to allow 90C cables a higher
capacity (more tables)... but there are plenty of manufacturers other
than Pirelli producing those :)
Yes but generically it is referred to a Pirelli whether Pirelli, AEI,
Delta or anyone else makes it.
Isn't LSF cable rated exactly the same as PVC of similar construction?
Yes, if you are referring to it's only having an insulant with low smoke
and fume properties with nothing else different.
I avoid PVC/PVC cable if at all possible particularly that T&E Brits
seem so keen on.

Never used your Flame Shielded stuff,
What is flame shielded? Pirelli you mean? :)
though I have seen it, but I can't find
it in the regs either. Does it come under MICS?
?
My regulations are in the vehicle.
Pirelli.co.uk/fp has datasheets on FP200 Gold and FP Plus
 
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M

Martin Angove

In message <[email protected]>,
geoff said:
It means he's welsh and, for some reason, wants to advertise the fact
Welsh, please - note the initial capital :) Cymro Cymraeg hefyd.

It's a sign-off I've been using for years and one of these days I'll
probably get bored with it and find another one, but it'll do for now.

As well as Andy's explanation of "fun or merriment" (but much more
than that) it is also a contraction of "hwyl fawr" which is the Welsh
equivalent of "goodbye", i.e. akin to "'bye".

If my Welshness offends you, please feel free to ignore me. It's a trick
the English have been using with the Welsh for some centuries and which
we are only now escaping from.

Actually, half my ancestors aren't actually Welsh at all, though they
are at least Celts - the Angoves (an Gof, the Smith) are Cornishmen.
Except for the South Africans, Canadians, Americans and wine-making
Australians ;-)

Hwyl!

M.
 
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