Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the
mains
can fail due to a fire in the wire before your meter. Happened to my
neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.

I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the
eaves, it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have
hummed very loudly and thrown sparks for a full 10 minutes. Also the
electric board guy confirmed it when I asked him. He said it was "too
expensive to fit them".

Odd. Ive got one :-)

charles wrote:
In article op.v5btgzznytk5n5@i7-940, Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter. Happened
to my neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.
I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the eaves,
it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have hummed
very loudly and thrown sparks for a full 10 minutes. Also the electric
board guy confirmed it when I asked him. He said it was "too expensive
to fit them".

and what sort of fuse would you fit at the substation? Houses aren't fed
via radial circuits from there. A feed leaves the sub and tens of houses
ae fed off that one feed. Certainly our sub, mounted on a pole has a fuse
on the output and it used to blow when there was an intermittent short
under the road.

There is, of course, a "company fuse" located in the customers premises
before the meter. If your description of the fault was correct, that
should have blown. Unless, sunny jim had tapped into the cable before
there to get free electricity.

AFAICT the short happened before that.

On Tue, 22 Nov 2011 03:22:16 -0000, John Rumm wrote:

On 22/11/2011 02:32, Lieutenant Scott wrote:
On Mon, 21 Nov 2011 09:17:19 -0000, Dave Liquorice
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, Lieutenant Scott wrote:

BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter. Happened to
my neighbour due to loose connection. Electric board too stupid to fuse
this wire at substation.

The feed would have been protected against a phase to phase or phase
to earth faults but a "loose coonection" is neither of those it just
gets hot due to the volt drop across it. 500A, 0.01 ohm = 2.5kW,
doesn't take much of a "loose connection" to produce significant
quantities of heat...

Firstly it's ONE hundred amps into a house, not FIVE. It should be fused
at 100 amps AT THE SUBSTATION to protect from faults on the external
side of your meter, but it isn't. There is no protection whatsoever
against shorting a house feed wire.

Houses are not usually individually wired to the substation. Typically
the three phases will leave the station and then be daisy chained to
many properties in rotation down the road. Hence you can't fuse them at
100A at the substation.

(However diversity does allow them to be fused far lower than one might
expect - 600A per phase is not uncommon IIUC even when there are dozens
of properties sharing a phase)

The wire feeding 1 property is not capable of 600 amps, therefore needs a more sensitive fuse.

--
http://petersparrots.com
http://petersphotos.com

Two men were talking.
"My son asked me what I did during the Sexual Revolution," said one.
"I told him I was captured early and spent the duration doing the dishes.

On Tue, 22 Nov 2011 03:25:49 -0000, John Rumm wrote:

On 21/11/2011 03:21, Lieutenant Scott wrote:
On Sun, 20 Nov 2011 22:08:33 -0000, Ghostrecon wrote:

On Thu, 17 Nov 2011 22:33:31 -0000, Lieutenant Scott wrote:

Just how much power do you use?!?!?

not much - Ive rarely seen more than 5Kw at one time since monitoring the
energy usage, but previous owners cooked with electricity, had
dishwasher,
tumble dryer and washing machine - odd arangement here - the two ring
mains are right and left in the house not up and down. The number of mbs
was more about isolation than power usage
Non-Rcd
Cooker - used for socket for fridge freezer
Immersion heater
upstairs Lighting ring
Downstairs lighting ring
Smoke alarms

RCD uses 2 slots
KItchen and u-room ring
Lefthand sockets
Righthand sockets
Garage ring (converted to bedroom)+Shed
Loft lighting (and outside light- hence the rcd)
Garage and u room lighting
+ 1 spare = 14 way

Why have an RCD on some stuff but not others?

Some circuits (lighting for example) pose very little electrocution
risk,

Oh I dunno, changing a lightbulb?

Besides, electrocution isn't all it's made out to be. I've had loads of shocks off the mains, never given me anything more than a fright and a warm hand. However I do know someone who fell off a ladder because he replaced a light when the circuit wasn't off like he thought it was. RCD didn't trip, "normal" breaker didn't trip. 5 amps live to neutral through him was enough to make him jump off the ladder.

but do pose a significant safety risk when interrupted so having
them sharing a RCD with many other circuits is not ideal.

Safety risk?!? Do you have circular saws in your living room or something? Darkness isn't the end of the world.

Some appliances typically exhibit high leakage currents, and are hence
likely to sensitise an RCD without gaining much safety benefit.

Which is why I'd never fit an RCD to my house.

BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter.

Yup they are usually fine on batteries...

You sound like you're speaking from experience!

--
http://petersparrots.com
http://petersphotos.com

If you jog in a jogging suit, lounge in lounging pajamas, and smoke in a smoking jacket, why would anyone want to wear a windbreaker?

On Tue, 22 Nov 2011 08:12:18 -0000, Dave Liquorice wrote:

On Tue, 22 Nov 2011 02:32:00 -0000, Lieutenant Scott wrote:

The feed would have been protected against a phase to phase or
phase
to earth faults but a "loose coonection" is neither of those it
just
gets hot due to the volt drop across it. 500A, 0.01 ohm = 2.5kW,
doesn't take much of a "loose connection" to produce significant
quantities of heat...

Firstly it's ONE hundred amps into a house, not FIVE. It should be
fused at 100 amps AT THE SUBSTATION to protect from faults on the
external side of your meter, but it isn't. There is no protection
whatsoever against shorting a house feed wire.

There will be protection but it will be several hundred amps per
phase and good old fuse not a fast acting MCB. You appear to be
making wrong assumptions about how power is distributed. As Mr Rumm
says in most cases several properties will share the same 230v feed
with them evenly spread across the three phases. Great use of
diversity is made, each individual house may have a "100A supply",
with the service cutout rated at 100A but most of the time they will
only be taking 5A or so (1kW), big loads like showers will only be on
for (relatively) short times and not at the same time as the other
houses. Being rural we have our "own" 11kV to 230v transformer up a
pole outside, the fuse on that pole is 200A (or was they recently
refurbished the stays and fuse and it's now 20' from the ground
instead of the nice handy eight).

If the fire brigade had had the sense to pull that out, my neighbour wouldn't have lost his roof to the fire. They told me they "weren't allowed to" - not that it was dangerous, but that the electricity board would get him into trouble. If it had ben my house, that fuse would have been out quick smart.

Secondly, the fire was caused by the house feed wire coming off the
meter fuse and the two ends touching. A short circuit, drawing as much current as the substation could put through the wire feeding the house.

Like most fuses a 500A fuse takes a considerable overload (think
several times it's rating to blow in anything under a minute. An
temporary fault type short on the short on the end of a customers
will not be able to sustain the power disipation required (100kW)
without exploding and reducing the fault current. The substation fuse
is to protect the distribution cables from gross faults not
individual supplies.

Why isn't there a 100 amp fuse at the point where the wire is divided to one property?

OH and actually, in his case, the wire to his house was overhead, and went straight to the transformer pole.

One can't help wondering how the ends of a service become
disconnected from the cut out and touch each other without external
influence...

The wind caused it. It was an overhead cable, which incidentally I had pointed out to the guy 4 months previously had a rather loose bracket. His response was "that's the electricity board's problem". It wasn't, it was his insurance company's problem when they had to pay for the entire house to be rebuilt.

--
http://petersparrots.com
http://petersphotos.com

Man: "Do you wash your clothes in Windex?"
Woman: "Why do you ask?"
Man: "I can see myself in your pants."

On Tue, 22 Nov 2011 08:14:35 -0000, Dave Liquorice wrote:

On Tue, 22 Nov 2011 02:35:13 -0000, Lieutenant Scott wrote:

What don't you believe? The fire? He had the wire going into the
eaves, it was an old house. The hot wire ignited the rafters.

and:

Secondly, the fire was caused by the house feed wire coming off the
meter fuse and the two ends touching.

Troll.

Why do people write "troll" when they don't believe something? I am telling the absolute truth - the thing came off it's mountings on a windy night because the brcaket had become detached from the eaves of his house.

--
http://petersparrots.com
http://petersphotos.com

A young teenager comes home from school and asks her mother, "Is it true what Rita just told me? That babies come out of the same place where boys put their thingies?"
"Yes, dear," replies her mother, pleased that the subject had finally come up and she wouldn't have to explain it.
"But then when I have a baby, won't it knock my teeth out?"

On Tue, 22 Nov 2011 09:22:40 -0000, The Natural Philosopher wrote:

Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the
mains
can fail due to a fire in the wire before your meter. Happened to my
neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.

I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the
eaves, it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have
hummed very loudly and thrown sparks for a full 10 minutes. Also the
electric board guy confirmed it when I asked him. He said it was "too
expensive to fit them".

Odd. Ive got one :-)

At 100 amps? Away from your house?

--
http://petersparrots.com
http://petersphotos.com

Cobra: 2 conjoined bras.

On Tue, 22 Nov 2011 06:31:01 -0000, charles wrote:

In article op.v5btgzznytk5n5@i7-940, Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter. Happened
to my neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.

I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the eaves,
it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have hummed
very loudly and thrown sparks for a full 10 minutes. Also the electric
board guy confirmed it when I asked him. He said it was "too expensive
to fit them".

and what sort of fuse would you fit at the substation? Houses aren't fed
via radial circuits from there. A feed leaves the sub and tens of houses
ae fed off that one feed. Certainly our sub, mounted on a pole has a fuse
on the output and it used to blow when there was an intermittent short
under the road.

At the junction box where it comes from the big ass cable under the pavement to go towards your property.

There is, of course, a "company fuse" located in the customers premises
before the meter. If your description of the fault was correct, that
should have blown. Unless, sunny jim had tapped into the cable before
there to get free electricity.

The short was at the point where the cable entered his roof. Before the main 100A fuse in his house.

--
http://petersparrots.com
http://petersphotos.com

From Hollywood Squares:
Host Peter Marshall: Charley, you've just decided to grow strawberries. Are you going to get any during your first year?
Charley Weaver: Of course not, Peter. I'm too busy growing strawberries!

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses aren't
fed via radial circuits from there. A feed leaves the sub and tens of
houses ae fed off that one feed. Certainly our sub, mounted on a pole
has a fuse on the output and it used to blow when there was an
intermittent short under the road.

At the junction box where it comes from the big ass cable under the
pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under the road.

--
From KT24

Using a RISC OS computer running v5.16

On Tue, 22 Nov 2011 11:42:15 -0000, charles wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses aren't
fed via radial circuits from there. A feed leaves the sub and tens of
houses ae fed off that one feed. Certainly our sub, mounted on a pole
has a fuse on the output and it used to blow when there was an
intermittent short under the road.

At the junction box where it comes from the big ass cable under the
pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under the road.

At some point the wire going to your house must seperate from the bigass one which services several houses. Are you saying they just twist the ends together?

--
http://petersparrots.com
http://petersphotos.com

The longest recorded flight of a chicken is thirteen seconds.

On Tue, 22 Nov 2011 11:13:01 -0000, Lieutenant Scott wrote:

The wire feeding 1 property is not capable of 600 amps, therefore needs
a more sensitive fuse.

Oh yes it is, it's capable of kilo amps. How long for before
something gives up in a spectacular fashion when kilo amps are
flowing is another matter.

--
Cheers
Dave.

In article op.v5ck04whytk5n5@i7-940, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 11:42:15 -0000, charles
wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses
aren't fed via radial circuits from there. A feed leaves the sub
and tens of houses ae fed off that one feed. Certainly our sub,
mounted on a pole has a fuse on the output and it used to blow when
there was an intermittent short under the road.

At the junction box where it comes from the big ass cable under the
pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under the
road.

At some point the wire going to your house must seperate from the bigass
one which services several houses. Are you saying they just twist the
ends together?

I suspect it's a properly soldered joint.

--
From KT24

Using a RISC OS computer running v5.16

On Tue, 22 Nov 2011 11:23:12 -0000, Lieutenant Scott wrote:

What don't you believe? The fire? He had the wire going into
the
eaves, it was an old house. The hot wire ignited the rafters.

and:

Secondly, the fire was caused by the house feed wire coming off
the
meter fuse and the two ends touching.

Troll.

Why do people write "troll" when they don't believe something? I am
telling the absolute truth - the thing came off it's mountings on a
windy night because the brcaket had become detached from the eaves of
his house.

So he has this "meter fuse" mounted at the eaves of his house? I bet
the meter readers love that. B-)

Inconsistency of story = troll.

--
Cheers
Dave.

On Tue, 22 Nov 2011 11:42:15 +0000, charles wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses aren't
fed via radial circuits from there. A feed leaves the sub and tens
of houses ae fed off that one feed. Certainly our sub, mounted on a
pole has a fuse on the output and it used to blow when there was an
intermittent short under the road.

At the junction box where it comes from the big ass cable under the
pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under the
road.

Yes, there is. It's under the road.

--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

On Tue, 22 Nov 2011 12:51:05 -0000, Dave Liquorice wrote:

On Tue, 22 Nov 2011 11:13:01 -0000, Lieutenant Scott wrote:

The wire feeding 1 property is not capable of 600 amps, therefore needs
a more sensitive fuse.

Oh yes it is, it's capable of kilo amps. How long for before
something gives up in a spectacular fashion when kilo amps are
flowing is another matter.

By capable, I meant without excessive heating. It will not be rated at 100s of amps.

--
http://petersparrots.com
http://petersphotos.com

What is the first thing a blonde learns when she takes driving lessons?
You can also sit upright in a car.

On Tue, 22 Nov 2011 12:54:29 -0000, charles wrote:

In article op.v5ck04whytk5n5@i7-940, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 11:42:15 -0000, charles
wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses
aren't fed via radial circuits from there. A feed leaves the sub
and tens of houses ae fed off that one feed. Certainly our sub,
mounted on a pole has a fuse on the output and it used to blow when
there was an intermittent short under the road.

At the junction box where it comes from the big ass cable under the
pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under the
road.

At some point the wire going to your house must seperate from the bigass
one which services several houses. Are you saying they just twist the
ends together?

I suspect it's a properly soldered joint.

And at this point, adding a fuse would not be a problem.

--
http://petersparrots.com
http://petersphotos.com

A great way to lose weight is to eat naked in front of a mirror. Restaurants will almost always throw you out before you can eat too much.

On Tue, 22 Nov 2011 12:55:13 -0000, Dave Liquorice wrote:

On Tue, 22 Nov 2011 11:23:12 -0000, Lieutenant Scott wrote:

What don't you believe? The fire? He had the wire going into
the
eaves, it was an old house. The hot wire ignited the rafters.

and:

Secondly, the fire was caused by the house feed wire coming off
the
meter fuse and the two ends touching.

Troll.

Why do people write "troll" when they don't believe something? I am
telling the absolute truth - the thing came off it's mountings on a
windy night because the brcaket had become detached from the eaves of
his house.

So he has this "meter fuse" mounted at the eaves of his house? I bet
the meter readers love that. B-)

Inconsistency of story = troll.

No, it's my neighbour where I used to live, not my own house. Therefore I only know what I've seen and what he's told me. Why would anyone go to the bother of creating a fictitious story with that much detail?

I did his gardening for him when I was a teenager, and when doing his hedge noticed that the cable was loose - the bracket had come off and the wire was supporting itself. I told him he should get it checked out, but he said it's the electricity board's problem. About 4 months later there was the fire. I have no idea where his meter was, I assume the big feed wire came downstairs inside the house. The point of the fire starting, according to the fire brigade, was in the attic - consistent with the mess I saw of the roof after they'd put it out. Perhaps the wire was severed at the point of entry to the roof, or there was a joiner up there. Whatever happened, the phase and the neutral/earth must have got joined together.

--
http://petersparrots.com
http://petersphotos.com

I still say a church steeple with a lightning rod on top shows a lack of confidence.

Lieutenant Scott wrote:
On Tue, 22 Nov 2011 12:54:29 -0000, charles
wrote:

In article op.v5ck04whytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 11:42:15 -0000, charles
wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses
aren't fed via radial circuits from there. A feed leaves the sub
and tens of houses ae fed off that one feed. Certainly our sub,
mounted on a pole has a fuse on the output and it used to blow
when there was an intermittent short under the road.

At the junction box where it comes from the big ass cable under
the pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under
the road.

At some point the wire going to your house must seperate from the
bigass one which services several houses. Are you saying they just
twist the ends together?

I suspect it's a properly soldered joint.

And at this point, adding a fuse would not be a problem.

Buried under the road? I suspect not.

Tim

Lieutenant Scott wrote:
On Tue, 22 Nov 2011 09:22:40 -0000, The Natural Philosopher
wrote:

Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the
mains
can fail due to a fire in the wire before your meter. Happened to my
neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.

I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the
eaves, it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have
hummed very loudly and thrown sparks for a full 10 minutes. Also the
electric board guy confirmed it when I asked him. He said it was "too
expensive to fit them".

Odd. Ive got one :-)

At 100 amps? Away from your house?

Yup. I have a personal substation in the corner of the garden :-)

Used to be 60A but it kept blowing, so they put in 100A and that blew
the cable as well..where the digger had hit it.

On Tue, 22 Nov 2011 14:10:48 -0000, Tim Downie wrote:

Lieutenant Scott wrote:
On Tue, 22 Nov 2011 12:54:29 -0000, charles
wrote:

In article op.v5ck04whytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 11:42:15 -0000, charles
wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:


[Snip]






There isn't such a junction box. All the wiring is buried under
the road.

At some point the wire going to your house must seperate from the
bigass one which services several houses. Are you saying they just
twist the ends together?

I suspect it's a properly soldered joint.

And at this point, adding a fuse would not be a problem.

Buried under the road? I suspect not.

It shouldn't blow apart from to protect buildings from extreme shorts like the one I mentioned. So it would probably never have to be accessed.

Having said that, my parents' one needed access. The tarmac over the top of it was not substantial enough when a heavy lorry parked on the pavement above it. The tarmac sunk. The council simply added more tarmac. When a lorry did the same thing again, the power was cut off. I suppose they're lucky it didn't cause a fire, although probably underground it wouldn't have come to much - unless their house had managed to receive two phases instead of one - I've seen the effects of that and it ain't nice.

--
http://petersparrots.com
http://petersphotos.com

When launching a boat, always back the boat into the water.
Pulling the boat into the water can really mess up your carburetor.

On Tue, 22 Nov 2011 14:25:47 -0000, The Natural Philosopher wrote:

Lieutenant Scott wrote:
On Tue, 22 Nov 2011 09:22:40 -0000, The Natural Philosopher
wrote:

Lieutenant Scott wrote:
On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike
wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:




I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the
eaves, it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have
hummed very loudly and thrown sparks for a full 10 minutes. Also the
electric board guy confirmed it when I asked him. He said it was "too
expensive to fit them".

Odd. Ive got one :-)

At 100 amps? Away from your house?

Yup. I have a personal substation in the corner of the garden :-)

Used to be 60A but it kept blowing, so they put in 100A and that blew
the cable as well..where the digger had hit it.

I'm not so sure your property has been well made.

--
http://petersparrots.com
http://petersphotos.com

You can't polish a turd, but it's funny as **** watching someone try.

On Mon, 21 Nov 2011 03:21:51 -0000, Lieutenant Scott wrote:

On Sun, 20 Nov 2011 22:08:33 -0000, Ghostrecon wrote:

On Thu, 17 Nov 2011 22:33:31 -0000, Lieutenant Scott wrote:

Just how much power do you use?!?!?

not much - Ive rarely seen more than 5Kw at one time since monitoring the
energy usage, but previous owners cooked with electricity, had dishwasher,
tumble dryer and washing machine - odd arangement here - the two ring
mains are right and left in the house not up and down. The number of mbs
was more about isolation than power usage
Non-Rcd
Cooker - used for socket for fridge freezer
Immersion heater
upstairs Lighting ring
Downstairs lighting ring
Smoke alarms

RCD uses 2 slots
KItchen and u-room ring
Lefthand sockets
Righthand sockets
Garage ring (converted to bedroom)+Shed
Loft lighting (and outside light- hence the rcd)
Garage and u room lighting
+ 1 spare = 14 way

Why have an RCD on some stuff but not others?


dont want nuisance trips to take out lights or freezer seemed sensible to
put smoke alarms on non rcd - garage conversion and so u room lighting
waere done last year so the lighting is still on non rcd need to get a new
busbar to move the rcd in the cu- whilst 240 volts across a dry body
contact may not kill I would rather not be in the circuit especially if a
wet contact is possible




BTW I take it the smoke alarms are ok on batteries, because all the mains can fail due to a fire in the wire before your meter. Happened to my neighbour due to loose connection. Electric board too stupid to fuse this wire at substation.


yes interlinked and battery backed up - think that was in the op that
started this sub thread

--
(º€¢.¸(¨*€¢.¸ ¸.€¢*¨)¸.€¢Âº)
.€¢Â°€¢. Nik .€¢Â°€¢.
(¸.€¢Âº(¸.€¢Â¨* *¨€¢.¸)º€¢.¸)

Ghostrecon wrote:
On Mon, 21 Nov 2011 03:21:51 -0000, Lieutenant Scott wrote:

On Sun, 20 Nov 2011 22:08:33 -0000, Ghostrecon wrote:

On Thu, 17 Nov 2011 22:33:31 -0000, Lieutenant Scott wrote:

Just how much power do you use?!?!?
not much - Ive rarely seen more than 5Kw at one time since monitoring the
energy usage, but previous owners cooked with electricity, had dishwasher,
tumble dryer and washing machine - odd arangement here - the two ring
mains are right and left in the house not up and down. The number of mbs
was more about isolation than power usage
Non-Rcd
Cooker - used for socket for fridge freezer
Immersion heater
upstairs Lighting ring
Downstairs lighting ring
Smoke alarms

RCD uses 2 slots
KItchen and u-room ring
Lefthand sockets
Righthand sockets
Garage ring (converted to bedroom)+Shed
Loft lighting (and outside light- hence the rcd)
Garage and u room lighting
+ 1 spare = 14 way
Why have an RCD on some stuff but not others?


dont want nuisance trips to take out lights or freezer seemed sensible to
put smoke alarms on non rcd - garage conversion and so u room lighting
waere done last year so the lighting is still on non rcd need to get a new
busbar to move the rcd in the cu- whilst 240 volts across a dry body
contact may not kill I would rather not be in the circuit especially if a
wet contact is possible


I went up to 100mA slow blow on total house to get rid of nuisance trips.


I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..




BTW I take it the smoke alarms are ok on batteries, because all the mains can fail due to a fire in the wire before your meter. Happened to my neighbour due to loose connection. Electric board too stupid to fuse this wire at substation.


yes interlinked and battery backed up - think that was in the op that
started this sub thread

Unlikely in my case, since it would blow the substation fuse - and has.

Comes out of de ground and into the meter box..think that's where the
company 'house fuse' is...

On 22/11/2011 16:15, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 15:22:32 -0000, John Rumm
wrote:

On 22/11/2011 11:16, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 03:25:49 -0000, John Rumm
wrote:

On 21/11/2011 03:21, Lieutenant Scott wrote:
On Sun, 20 Nov 2011 22:08:33 -0000, Ghostrecon wrote:

On Thu, 17 Nov 2011 22:33:31 -0000, Lieutenant Scott wrote:



not much - Ive rarely seen more than 5Kw at one time since
monitoring the
energy usage, but previous owners cooked with electricity, had
dishwasher,
tumble dryer and washing machine - odd arangement here - the two ring
mains are right and left in the house not up and down. The number of
mbs
was more about isolation than power usage
Non-Rcd
Cooker - used for socket for fridge freezer
Immersion heater
upstairs Lighting ring
Downstairs lighting ring
Smoke alarms

RCD uses 2 slots
KItchen and u-room ring
Lefthand sockets
Righthand sockets
Garage ring (converted to bedroom)+Shed
Loft lighting (and outside light- hence the rcd)
Garage and u room lighting
+ 1 spare = 14 way

Why have an RCD on some stuff but not others?

Some circuits (lighting for example) pose very little electrocution
risk,

Oh I dunno, changing a lightbulb?

Not much of a risk usually. A typical bayonet connector only has a small
live surface you can touch, and not in a way you can grab hold of it
easily.

Unless the fitting comes loose exposing wires that aren't supposed to be
exposed.

Even less likely - but again, you are in a situation where you are
unlikely to be well earthed. If you made contact with both live and
neutral then you would get a nasty shock to the hand, but it would not
be through any major organs. Also the effect of the jolt / passing out
etc will tend to break contact which minimises the duration.

Light fittings are exceedingly rarely a cause of electrocution.

Besides, electrocution isn't all it's made out to be. I've had loads of
shocks off the mains, never given me anything more than a fright and a

Much depends on how good your connection to earth is at the time of the
shock.

I've had shocks within one hand and across my body from one hand to the
other. I guess I don't have a weak heart.

Weak or otherwise, the wrong set of circumstances will either stop it,
or more likely result in ventricular fibrillation.

warm hand. However I do know someone who fell off a ladder because he
replaced a light when the circuit wasn't off like he thought it was. RCD
didn't trip, "normal" breaker didn't trip. 5 amps live to neutral
through him was enough to make him jump off the ladder.

Until recently, the use of RCDs on lighting circuits was uncommon. So
there is a fair chance that it was not even supplying that circuit. A 6A
MCB will need 30A to trip "instantly", and there is little chance of
passing that through a body at 240V, hence it offers no protection from
direct contact at all (and is not supposed to either)

Kinda puts a damper on the belief by some that they are safer than
fuses. More convenient yes, but not safer.

Depends on the type of fuse... compared to BS3036 rewireable ones they
perform better, and hence one does not need to design circuits with a
current derating on the cable for installation. Also there is no chance
an ill informed user can rewire them with the wrong wire / tin foil etc.

Compared to a cartridge fuse, then they are no better (and in some cases
once could argue not as good (i.e. they are more likely to trip on a
incandescent bulb failure than a fuse). However they are certainly more
convenient.

I have fitted MCBs ONLY to my lighting circuit. This because I have
automatic lights, the sensors are very susceptible to surges, and
putting a fuse carrier back in is not a clean switch on.

You ought not be re-energising under load anyway... not good for fuse or
MCB contacts.

but do pose a significant safety risk when interrupted so having
them sharing a RCD with many other circuits is not ideal.

Safety risk?!? Do you have circular saws in your living room or
something? Darkness isn't the end of the world.

Depends on what you are doing when it occurs. Fewer than 20 people will
be killed by their fixed wiring in any give year, however thousands will
die as a result of trips and falls in their own home.

(note there is a mistake in what I said above... the 20 deaths/year are
from *all* sources of electrocution including misuse of portable
appliances - those from fixed wiring typically used to amount to one or
two a year (although there is evidence that this is now increasing
following the introduction of part P of the building regs (as you would
expect)))

And the majority of those have nothing to do with unexpected darkness.

Probably true, however it was found that there were sufficient number of
serious falls in darkness that resulted from nuisance RCD trips to cause
a revision of the guidance on RCDs originally included in the 15th
edition of the regs.

Some appliances typically exhibit high leakage currents, and are hence
likely to sensitise an RCD without gaining much safety benefit.

Which is why I'd never fit an RCD to my house.

You would be monumentally stupid not to, since should you ever be
exposed to a life threatening shock, there is a fair chance that one
would save you.

As stated earlier, 240 volt shocks are not life threatening to healthy
people.

That is complete and utter ********.

For several reasons....

Firstly 240V shocks can and do kill perfectly healthy people every year.

Secondly there is a much larger class of people who will be seriously
injured and suffer permanent after effects as a result of shocks.

There are an even greater number of will suffer serious but recoverable
injury, and still more that will be hurt to various degrees.

Research conducted by the National Safety Council shows that in the UK
there are something like 1 million hospital visits resulting from
electrical shocks per year. (obviously these include minor burns cuts
and bruises, right up to cardiac damage, severe burns / disfigurement
etc, and deaths).

I tell you what would be safer though - not earthing so many things.
Imagine this - you touch something live, you get a tingle. Now imagine
you are leaning against an earthed sink, washing machine, etc, etc. Now
you are a circuit. Why did people think an earth was a good idea?

You seem to be misunderstanding the whole purpose of earthing. It is not
there to reduce the shock potential difference you might be exposed to.
It is designed to operated in conjunction with a circuit protective
device to de-energise a circuit in the event of a fault.

If a wire falls off in some appliance and makes the metal case live, the
earthing connection to the case will ensure enough fault current flows
to blow a fuse or trip a MCB - thus limiting the maximum shock duration
to something survivable.

The argument that you are safer with no earths around is true, but only
when you can ensure there is *no* access to any independent earth. If
there is, then you need to make sure that the earth is "good" or else
you may not get adequate fault current flowing to operated the CPD while
at the same time having an earth good enough to kill you.

If you want to seek to reduce the magnitude of potential difference that
you might be exposed to, you need equipotential bonding. This is
typically used in location where people are highly vulnerable to
electric shock (e.g. when wet / naked / barefoot etc as in bath and
shower rooms).

RCDs add another layer of protection by limiting shock duration by
detecting current imbalance. They work particularly well for people
(mis)using appliances outside etc or any other situation where you have
unwittingly become part of a circuit.


However, they also need to be used sensibly. The days of a single a RCD
protecting a whole installation are long gone. Any sensible design will
use multiple RCDs with circuits grouped sensibly. Better still a whole
RCBO installation that has one RCD per circuit is becoming cost feasible
these days.

RCD/MCB in the same part is what I see installed in commercial premises.
Although the cost may be higher than domestic installations....

Yup, that is a RCBO. (Residual current Circuit Breaker with Overload
protection)

Details he

http://wiki.diyfaq.org.uk/index.php?title=RCD

BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter.

Yup they are usually fine on batteries...

You sound like you're speaking from experience!

I am, I have mains powered interlinked alarms with internal rechargeable
batteries. When I first installed them, and had not completed the mains
connection, they ran for several months from their batteries.

Oh, incompletion. Not a fire :-)

Either way - the duration of the former is significantly longer than any
fire one is likely to encounter.


--
Cheers,

John.

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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Lieutenant Scott wrote:

Why did people think an earth was
a good idea?

It was God's idea.

We just use it.

--
Adam

* Sometimes I like to lay in my neighbours garden and pretend to be a
carrot *

On 22/11/2011 19:14, The Natural Philosopher wrote:

I went up to 100mA slow blow on total house to get rid of nuisance trips.

I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..

Or stick all the outside / outbuilding circuits on their own CU and with
its own (time delayed) RCD (TT Here)





BTW I take it the smoke alarms are ok on batteries, because all the
mains can fail due to a fire in the wire before your meter. Happened
to my neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.


yes interlinked and battery backed up - think that was in the op that
started this sub thread
Unlikely in my case, since it would blow the substation fuse - and has.

Comes out of de ground and into the meter box..think that's where the
company 'house fuse' is...


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
On 22/11/2011 19:14, The Natural Philosopher wrote:

I went up to 100mA slow blow on total house to get rid of nuisance trips.

I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..

Or stick all the outside / outbuilding circuits on their own CU and with
its own (time delayed) RCD (TT Here)

I'm a tad less rural/farm than you are John :-)

On 22/11/2011 22:09, The Natural Philosopher wrote:
John Rumm wrote:
On 22/11/2011 19:14, The Natural Philosopher wrote:

I went up to 100mA slow blow on total house to get rid of nuisance
trips.

I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..

Or stick all the outside / outbuilding circuits on their own CU and
with its own (time delayed) RCD (TT Here)

Putting outside circuits on their own CU was really a way of making sure
they could have no influence on the house electrics - even to the point
of not sharing RCD leakage budget.

I'm a tad less rural/farm than you are John :-)

Really, I had visions of you out in the sticks a bit... How long would
it take you to walk to the nearest shop? (probably about 15 mins from here)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tue, 22 Nov 2011 02:35:13 -0000, "Lieutenant Scott"
wrote:

On Mon, 21 Nov 2011 12:33:59 -0000, The Other Mike wrote:

On Mon, 21 Nov 2011 03:21:51 -0000, "Lieutenant Scott"
wrote:


BTW I take it the smoke alarms are ok on batteries, because all the mains
can fail due to a fire in the wire before your meter. Happened to my
neighbour due to loose connection. Electric board too stupid to
fuse this wire at substation.

I find that hard, no make that impossible, to believe.

What don't you believe? The fire? He had the wire going into the eaves, it was an old house. The hot wire ignited the rafters.

The non-fusing? If there was a fuse, the substation wouldn't have hummed very loudly and thrown sparks for a full 10 minutes. Also the electric board guy confirmed it when I asked him. He said it was "too expensive to fit them".


Possible facts:

You saw a fire
Maybe that fire was caused by electricity


Definite facts:

The cable was fused at the substation to protect the cable
There is no way to bypass the fuse carrier at the substation


Possible fact:

The fuse rating may have been incorrectly chosen


Definite non fact:

Fuses are not too expensive to fit


Definte fact:

Fuses cost less than half a dozen metres of cable


The End
--

John Rumm wrote:
On 22/11/2011 22:09, The Natural Philosopher wrote:
John Rumm wrote:
On 22/11/2011 19:14, The Natural Philosopher wrote:

I went up to 100mA slow blow on total house to get rid of nuisance
trips.

I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..

Or stick all the outside / outbuilding circuits on their own CU and
with its own (time delayed) RCD (TT Here)

Putting outside circuits on their own CU was really a way of making sure
they could have no influence on the house electrics - even to the point
of not sharing RCD leakage budget.

I'm a tad less rural/farm than you are John :-)

Really, I had visions of you out in the sticks a bit... How long would
it take you to walk to the nearest shop? (probably about 15 mins from here)

similar, but I don't have lossa outbuildings

On 22/11/2011 23:58, The Natural Philosopher wrote:
John Rumm wrote:
On 22/11/2011 22:09, The Natural Philosopher wrote:
John Rumm wrote:
On 22/11/2011 19:14, The Natural Philosopher wrote:

I went up to 100mA slow blow on total house to get rid of nuisance
trips.

I ought to put RCBO's on the 13A rings, esp the ones that go outside..

Round Tuit etc..

Or stick all the outside / outbuilding circuits on their own CU and
with its own (time delayed) RCD (TT Here)

Putting outside circuits on their own CU was really a way of making
sure they could have no influence on the house electrics - even to the
point of not sharing RCD leakage budget.

I'm a tad less rural/farm than you are John :-)

Really, I had visions of you out in the sticks a bit... How long would
it take you to walk to the nearest shop? (probably about 15 mins from
here)

similar, but I don't have lossa outbuildings

Me neither (yet - got some planned though). Got a feed to garden sockets
and pond, another to garage/workshop, and one for outside lights/PIRs (+
one low current socket). The garage has its own split load in it, and
that also has a feed to a shed.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Which is why I'd never fit an RCD to my house.

You would be monumentally stupid not to, since should you ever be
exposed to a life threatening shock, there is a fair chance that one
would save you.

As stated earlier, 240 volt shocks are not life threatening to healthy people.


That is the most stupid bit of total ******** I've ever seen writ on this ng!.

I suggest you read up on the subject before you make statements like that
here..


It is nothing at all to do with how "healthy" your heart is, and everything to
do with how conductive is the path of the current across your nervous system.



I tell you what would be safer though - not earthing so many things. Imagine
this - you touch something live, you get a tingle. Now imagine you are leaning
against an earthed sink, washing machine, etc, etc. Now you are a circuit. Why
did people think an earth was a good idea?

More codswallop..


--
Tony Sayer

On Tue, 22 Nov 2011 16:15:07 -0000, Lieutenant Scott wrote:

I've had shocks within one hand and across my body from one hand to the
other. I guess I don't have a weak heart.

No just fairly dry skin. Please try the same with wet hands, I doubt
you will be able to report back.

I tell you what would be safer though - not earthing so many things.
Imagine this - you touch something live, you get a tingle. Now imagine
you are leaning against an earthed sink, washing machine, etc, etc. Now
you are a circuit. Why did people think an earth was a good idea?

Learn the difference between "equipotential bonding" and "earthing".

--
Cheers
Dave.

On Wed, 23 Nov 2011 12:02:36 -0000, Dave Liquorice wrote:

On Tue, 22 Nov 2011 16:15:07 -0000, Lieutenant Scott wrote:

I've had shocks within one hand and across my body from one hand to the
other. I guess I don't have a weak heart.

No just fairly dry skin. Please try the same with wet hands, I doubt
you will be able to report back.

Have done it with both. With wet hands all the muscles jump - the only danger is falling off something, or bashing your head against something hard or sharp.

I tell you what would be safer though - not earthing so many things.
Imagine this - you touch something live, you get a tingle. Now imagine
you are leaning against an earthed sink, washing machine, etc, etc. Now
you are a circuit. Why did people think an earth was a good idea?

Learn the difference between "equipotential bonding" and "earthing".

Do tell us then, and show off your knowledge....

--
http://petersparrots.com
http://petersphotos.com

What's a diaphragm?
A trampoline for dickheads.

tony sayer wrote:
Which is why I'd never fit an RCD to my house.

You would be monumentally stupid not to, since should you ever be
exposed to a life threatening shock, there is a fair chance that one
would save you.

As stated earlier, 240 volt shocks are not life threatening to
healthy people.


That is the most stupid bit of total ******** I've ever seen writ on
this ng!.

Considering that dennis posts here that is quite a statement:-)

--
Adam

* Sometimes I like to lay in my neighbours garden and pretend to be a
carrot *

On Tue, 22 Nov 2011 22:05:47 -0000, ARWadsworth wrote:

Lieutenant Scott wrote:

Why did people think an earth was
a good idea?

It was God's idea.

We just use it.

God doesn't exist, therefore you vanish in a puff of logic and I win.

--
http://petersparrots.com
http://petersphotos.com

Those giraffes you sold me, they won't mate.
They just walk around, eating, and not mating.
You sold me queer giraffes! I want my money back!

On Tue, 22 Nov 2011 16:22:36 -0000, charles wrote:

In article op.v5cvmwywytk5n5@i7-940,
Lieutenant Scott wrote:
On Tue, 22 Nov 2011 15:53:14 -0000, charles wrote:

In article ,
Tim Downie wrote:
Lieutenant Scott wrote:
On Tue, 22 Nov 2011 12:54:29 -0000, charles
wrote:

In article op.v5ck04whytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 11:42:15 -0000, charles
wrote:

In article op.v5ch0it0ytk5n5@i7-940, Lieutenant Scott
wrote:
On Tue, 22 Nov 2011 06:31:01 -0000, charles
wrote:

[Snip]

and what sort of fuse would you fit at the substation? Houses
aren't fed via radial circuits from there. A feed leaves the sub
and tens of houses ae fed off that one feed. Certainly our sub,
mounted on a pole has a fuse on the output and it used to blow
when there was an intermittent short under the road.

At the junction box where it comes from the big ass cable under
the pavement to go towards your property.


There isn't such a junction box. All the wiring is buried under
the road.

At some point the wire going to your house must seperate from the
bigass one which services several houses. Are you saying they just
twist the ends together?

I suspect it's a properly soldered joint.

And at this point, adding a fuse would not be a problem.

Buried under the road? I suspect not.

but it is.

Pavement in the case I saw.

yes, I've seen them there, but we have no pavement on our side of the road.
the cable is simply under the carriageway.

A fuse could be place there.

--
http://petersparrots.com
http://petersphotos.com

Paper clips are the larval stage of coat hangers.

On Tue, 22 Nov 2011 20:17:22 -0000, John Rumm wrote:

On 22/11/2011 16:15, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 15:22:32 -0000, John Rumm
wrote:

On 22/11/2011 11:16, Lieutenant Scott wrote:
On Tue, 22 Nov 2011 03:25:49 -0000, John Rumm
wrote:

On 21/11/2011 03:21, Lieutenant Scott wrote:




Some circuits (lighting for example) pose very little electrocution
risk,

Oh I dunno, changing a lightbulb?

Not much of a risk usually. A typical bayonet connector only has a small
live surface you can touch, and not in a way you can grab hold of it
easily.

Unless the fitting comes loose exposing wires that aren't supposed to be
exposed.

Even less likely - but again, you are in a situation where you are
unlikely to be well earthed. If you made contact with both live and
neutral then you would get a nasty shock to the hand, but it would not
be through any major organs. Also the effect of the jolt / passing out
etc will tend to break contact which minimises the duration.

Light fittings are exceedingly rarely a cause of electrocution.

Except when some health and safety ****t insists the fitting gets earthed. Hold the fitting with the left hand and change the bulb with the right....

Besides, electrocution isn't all it's made out to be. I've had loads of
shocks off the mains, never given me anything more than a fright and a

Much depends on how good your connection to earth is at the time of the
shock.

I've had shocks within one hand and across my body from one hand to the
other. I guess I don't have a weak heart.

Weak or otherwise, the wrong set of circumstances will either stop it,
or more likely result in ventricular fibrillation.

The heart has approximately 5 signals to keep it going. It's not easy to stop it.

warm hand. However I do know someone who fell off a ladder because he
replaced a light when the circuit wasn't off like he thought it was. RCD
didn't trip, "normal" breaker didn't trip. 5 amps live to neutral
through him was enough to make him jump off the ladder.

Until recently, the use of RCDs on lighting circuits was uncommon. So
there is a fair chance that it was not even supplying that circuit. A 6A
MCB will need 30A to trip "instantly", and there is little chance of
passing that through a body at 240V, hence it offers no protection from
direct contact at all (and is not supposed to either)

Kinda puts a damper on the belief by some that they are safer than
fuses. More convenient yes, but not safer.

Depends on the type of fuse... compared to BS3036 rewireable ones they
perform better, and hence one does not need to design circuits with a
current derating on the cable for installation. Also there is no chance
an ill informed user can rewire them with the wrong wire / tin foil etc.

What's with no amperages matching up? 5 amp fuse, 6 amp breaker, and the "lighting" cable in Wickes is 13 amps!

Compared to a cartridge fuse, then they are no better (and in some cases
once could argue not as good (i.e. they are more likely to trip on a
incandescent bulb failure than a fuse). However they are certainly more
convenient.

I'd prefer them to trip when an incandescent fails. My fuse didn't and the buggered halogen spot took out the automatic light switch circuitry.

I have fitted MCBs ONLY to my lighting circuit. This because I have
automatic lights, the sensors are very susceptible to surges, and
putting a fuse carrier back in is not a clean switch on.

You ought not be re-energising under load anyway... not good for fuse or
MCB contacts.

Very inconvenient not to. And impossible for me. My light switches are automated.

but do pose a significant safety risk when interrupted so having
them sharing a RCD with many other circuits is not ideal.

Safety risk?!? Do you have circular saws in your living room or
something? Darkness isn't the end of the world.

Depends on what you are doing when it occurs. Fewer than 20 people will
be killed by their fixed wiring in any give year, however thousands will
die as a result of trips and falls in their own home.

(note there is a mistake in what I said above... the 20 deaths/year are
from *all* sources of electrocution including misuse of portable
appliances - those from fixed wiring typically used to amount to one or
two a year (although there is evidence that this is now increasing
following the introduction of part P of the building regs (as you would
expect)))

IN creasing?

And the majority of those have nothing to do with unexpected darkness.

Probably true, however it was found that there were sufficient number of
serious falls in darkness that resulted from nuisance RCD trips to cause
a revision of the guidance on RCDs originally included in the 15th
edition of the regs.

We need to get rid of these paper pushers.

Some appliances typically exhibit high leakage currents, and are hence
likely to sensitise an RCD without gaining much safety benefit.

Which is why I'd never fit an RCD to my house.

You would be monumentally stupid not to, since should you ever be
exposed to a life threatening shock, there is a fair chance that one
would save you.

As stated earlier, 240 volt shocks are not life threatening to healthy
people.

That is complete and utter ********.

For several reasons....

Firstly 240V shocks can and do kill perfectly healthy people every year.

All 20 of them. Big deal.

So why am I still in one piece?

Secondly there is a much larger class of people who will be seriously
injured and suffer permanent after effects as a result of shocks.

There are an even greater number of will suffer serious but recoverable
injury, and still more that will be hurt to various degrees.

Research conducted by the National Safety Council shows that in the UK
there are something like 1 million hospital visits resulting from
electrical shocks per year. (obviously these include minor burns cuts
and bruises, right up to cardiac damage, severe burns / disfigurement
etc, and deaths).

990,000 of them because their finger is a bit sore.

I tell you what would be safer though - not earthing so many things.
Imagine this - you touch something live, you get a tingle. Now imagine
you are leaning against an earthed sink, washing machine, etc, etc. Now
you are a circuit. Why did people think an earth was a good idea?

You seem to be misunderstanding the whole purpose of earthing. It is not
there to reduce the shock potential difference you might be exposed to.
It is designed to operated in conjunction with a circuit protective
device to de-energise a circuit in the event of a fault.

If a wire falls off in some appliance and makes the metal case live, the
earthing connection to the case will ensure enough fault current flows
to blow a fuse or trip a MCB - thus limiting the maximum shock duration
to something survivable.

The argument that you are safer with no earths around is true, but only
when you can ensure there is *no* access to any independent earth. If
there is, then you need to make sure that the earth is "good" or else
you may not get adequate fault current flowing to operated the CPD while
at the same time having an earth good enough to kill you.

If you want to seek to reduce the magnitude of potential difference that
you might be exposed to, you need equipotential bonding. This is
typically used in location where people are highly vulnerable to
electric shock (e.g. when wet / naked / barefoot etc as in bath and
shower rooms).

Er..... if everything is earthed, they ARE at the same potential.

RCDs add another layer of protection by limiting shock duration by
detecting current imbalance. They work particularly well for people
(mis)using appliances outside etc or any other situation where you have
unwittingly become part of a circuit.

I've had a few shocks from mowers in the rain etc. Never done me any harm.

Yup they are usually fine on batteries...

You sound like you're speaking from experience!

I am, I have mains powered interlinked alarms with internal rechargeable
batteries. When I first installed them, and had not completed the mains
connection, they ran for several months from their batteries.

Oh, incompletion. Not a fire :-)

Either way - the duration of the former is significantly longer than any
fire one is likely to encounter.

One would hope so!

--
http://petersparrots.com
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An optimist thinks this is the best possible world.
A pessimist fears this is true.

Lieutenant Scott wrote:


I suspect it's a properly soldered joint.

And at this point, adding a fuse would not be a problem.

Buried under the road? I suspect not.

but it is.

Pavement in the case I saw.

yes, I've seen them there, but we have no pavement on our side of the
road.
the cable is simply under the carriageway.

A fuse could be place there.


Joints used to be ferruled and soldered. These days they are more often
crimped, I believe.

Fuses exist in "link boxes" which are in the road, accessible with a visible
lid (obviously) and more often occur when a feed splits off to service a
side road, but not always (could be a solid joint, or you could have a link
box somewhere along a straight section of road). The fuses which are fitted
in 3's (3 phases) vary from typically 300A to 500A.

Having a visible box marked "SEEBOARD" or some such is no guarantee of
presence of fuses - it could also be a fuse box fitted with solid links
(copper bars) if the engineers decided a fuse at that position was not
actually useful, or wanted the option to fuse later.

This is why, if you put a spade through the cable under your drive that
feeds your house, you'll get a not inconsiderable bang.

--
Tim Watts

Lieutenant Scott wrote:

On Tue, 22 Nov 2011 20:17:22 -0000, John Rumm

Light fittings are exceedingly rarely a cause of electrocution.

Except when some health and safety ****t insists the fitting gets earthed.
Hold the fitting with the left hand and change the bulb with the
right....


And why the British system is superior to say, the Chinese system. My son
got a belt unscrewing an ES lamp from a fitting in China due to:

1) It being an ES fitting[1];

2) China, in common with a lot of countries has no enforcement of polarity
so in this case the cap happend to be live rather than the tip[2].

[1] Modern British ES fittings disengage on the first turn or so, the old
ones of course just had an all metal recepticle. However, even in Britain,
plenty of the older type exist.

[2] Even if the British regs demand the tip be live and the cap be neutral,
there's no guarantee some pillock hasn't wired it up wrong.

Which is why I hate ES fittings, and regard BC as generally a better idea.




--
Tim Watts