"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.

"Rod Speed" wrote in message
...


"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.


Bus, train, walk?


--
Adam

On Sun, 08 Nov 2015 19:21:54 -0000, ARW wrote:

"Rod Speed" wrote in message
...


"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.


Bus, train, walk?

NO!!!! There are enough ****ing buses in my way as it is!

--
Exersize: the act of removing excess baggage

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault). Now, consider an earth
fault after the fuse on pole A. Pole B is now at line voltage to earth
because neither fuse will blow (there is insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from pole
B to earth. A second earth fault or overcurrent, now on pole B, will blow
one or both of the fuses - but it's anyone's guess which one as they will
have to have the same rating. Now, is the supply earthed or not? Which
side is live to earth (if either)?

This sort of system is possible (it is actually used in some specialist
situations).

On Sun, 08 Nov 2015 20:05:38 -0000, mick wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly. My parents' neighbour's roof burnt down because his shorted incoming didn't blow any fuse. Apparently the only fuse is about 800A on the transformer, and the wire going to his house is 100A.

Now, consider an earth
fault after the fuse on pole A. Pole B is now at line voltage to earth
because neither fuse will blow (there is insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from pole
B to earth.

But you can already do that now, without it floating.

A second earth fault or overcurrent, now on pole B, will blow
one or both of the fuses - but it's anyone's guess which one as they will
have to have the same rating. Now, is the supply earthed or not? Which
side is live to earth (if either)?

This sort of system is possible (it is actually used in some specialist
situations).

--
Hickory dickory dock, three mice ran up the clock. The clock struck one, and the others got away with minor injuries.

"ARW" wrote in message
...
"Rod Speed" wrote in message
...


"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.


Bus, train, walk?

Bet yours turn their noses up at those.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 19:21:54 -0000, ARW
wrote:

"Rod Speed" wrote in message
...


"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 16:50:11 -0000, ARW

wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.


Bus, train, walk?

NO!!!! There are enough ****ing buses in my way as it is!

He's not suggesting they **** on those, stupid.

On Sunday, November 8, 2015 at 7:00:45 PM UTC, Rod Speed wrote:
"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.

Quite I have recently spend enough to buy a small island somewhere so that my wife could learn to drive.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:05:38 -0000, mick wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

A second earth fault or overcurrent, now on pole B, will blow
one or both of the fuses - but it's anyone's guess which one as they will
have to have the same rating. Now, is the supply earthed or not? Which
side is live to earth (if either)?

This sort of system is possible (it is actually used in some specialist
situations).

But not with normal house supplys.

On Sun, 08 Nov 2015 20:32:19 -0000, wrote:

On Sunday, November 8, 2015 at 7:00:45 PM UTC, Rod Speed wrote:
"ARW" wrote in message
...
"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

Bugger that, then we'd have to drive them everywhere.

Quite I have recently spend enough to buy a small island somewhere so that my wife could learn to drive.

but women have a habit of driving into water.

--
A sheet of sandpaper makes a cheap and effective substitute for costly maps when visiting the Sahara desert.

On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:05:38 -0000, mick wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

We have a fuse for the wire coming from each phase in the substation, but that branches to several houses, with thinner cables!

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

A second earth fault or overcurrent, now on pole B, will blow
one or both of the fuses - but it's anyone's guess which one as they will
have to have the same rating. Now, is the supply earthed or not? Which
side is live to earth (if either)?

This sort of system is possible (it is actually used in some specialist
situations).

But not with normal house supplys.

--
It said, "Insert disk #3," but only two will fit!

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the power
poles.

The ones that sit on the ground don't have them visible, but they have them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the individual
houses.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that way.

A second earth fault or overcurrent, now on pole B, will blow
one or both of the fuses - but it's anyone's guess which one as they
will
have to have the same rating. Now, is the supply earthed or not? Which
side is live to earth (if either)?

This sort of system is possible (it is actually used in some specialist
situations).

But not with normal house supplys.

On Sun, 08 Nov 2015 17:50:38 +0000, Tough Guy no. 1265 wrote:

Yeah right, I suppose you believe that story about a 9V PP3 in a
multimeter killing an army guy too.

It might *just* be possible. Especially if he had a heart condition. The
story goes that he pierced his thumbs with needles before connecting the
battery. In doing so, he entirely removed his only natural protection,
his skin resistance. The tissues under the skin have a much lower
resistance, in the order of 300 ohms. A 9V battery could therefore source
30mA across the chest. It's possible in theory at least.

On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the power
poles.

The ones that sit on the ground don't have them visible, but they have them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire from the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that way.

But with my scheme you can only get a shock if there are two faults. With the current scheme you only need one fault.

--
Das Computer Maschine Ist Nich Fur Gefingerenpoken Und Mittengrabben!
Ist Easy Schnappen Der Springenwerken Mit Spitzensparken Und Poppenkorken!
Das Rubbernecken Sightseeren Mus Keep Der Handz In Der Pockets, Relax Und Vatch Die Blinkenlights!!

On Sun, 08 Nov 2015 21:36:21 -0000, Cursitor Doom wrote:

On Sun, 08 Nov 2015 17:50:38 +0000, Tough Guy no. 1265 wrote:

Yeah right, I suppose you believe that story about a 9V PP3 in a
multimeter killing an army guy too.

It might *just* be possible. Especially if he had a heart condition. The
story goes that he pierced his thumbs with needles before connecting the
battery. In doing so, he entirely removed his only natural protection,
his skin resistance. The tissues under the skin have a much lower
resistance, in the order of 300 ohms. A 9V battery could therefore source
30mA across the chest. It's possible in theory at least.

Must have had a heart condition. Unless you actually jabbed the probes into the chest next to the heart, I doubt there'd be anything like enough current for the heart to care. Remember, it wasn't even a 9V battery, it was the current from the meter in ohms mode, which with mine won't even light an LED. It'd be a pretty **** meter if it needed a large current to test something, you might be testing very small components which won't carry that much.

--
Customer explaining flooded car to insurance claim investigator:
"It didn't look that deep at first glance - it only came half way up the ducks."

Tough Guy no. 1265 wrote:
On Sun, 08 Nov 2015 17:56:59 -0000, ARW
wrote:
"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The
replies don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)

Just the one. Ban women drivers.

You will get complete agreement from me on that. They have slow
reactions and no spatial awareness.

Ahhhh, the little yellow **** all who screamed abuse at a lone female driver
when she chucked a fag end out of her car window.
When asked if he would have screamed abuse at a male driver his reply was:
"Of course not, I'm not stupid".
I remember things, you little yellow **** all.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer
secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the
power
poles.

The ones that sit on the ground don't have them visible, but they have
them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire from
the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now
at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that
way.

But with my scheme you can only get a shock if there are two faults.

But there is no way to detect the initial earth fault,
so it will go unnoticed until someone gets a shock
and many won't be aware of the significance of that.

With the current scheme you only need one fault.

But non faults can kill you because the RCD will protect you.

The only problem is with a fault which results in the individual
ending up across the live an neutral with the current flowing
up one arm and down the other etc and that is very very
unlikely indeed and most of the time will trip the RCD anyway.

On Sun, 08 Nov 2015 22:06:11 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both poles
(I'm calling them A & B rather than L & N) at the transformer
secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the
power
poles.

The ones that sit on the ground don't have them visible, but they have
them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire from
the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is now
at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that
way.

But with my scheme you can only get a shock if there are two faults.

But there is no way to detect the initial earth fault,
so it will go unnoticed until someone gets a shock
and many won't be aware of the significance of that.

They're rare. And probably if a wire comes loose in the appliance and earths it, the wire is no longer where it should be and the appliance doesn't work. That would get noticed.

With the current scheme you only need one fault.

But non faults can kill you because the RCD will protect you.

RCDs didn't used to exist, so isolated mains would have been more sensible then. Even now, not everyone has them. I certainly don't. And I laugh at people who have nuisance trips.

The only problem is with a fault which results in the individual
ending up across the live an neutral with the current flowing
up one arm and down the other etc and that is very very
unlikely indeed and most of the time will trip the RCD anyway.

The RCD wouldn't stop that at all.

--
All the American flags on the moon have been bleached by radiation from the sun (which can only be a good thing).

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 22:06:11 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both
poles
(I'm calling them A & B rather than L & N) at the transformer
secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the
power
poles.

The ones that sit on the ground don't have them visible, but they have
them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the
individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire from
the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is
now
at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that
way.

But with my scheme you can only get a shock if there are two faults.

But there is no way to detect the initial earth fault,
so it will go unnoticed until someone gets a shock
and many won't be aware of the significance of that.

They're rare.

Not rare at all in fact.

And probably if a wire comes loose in the appliance and earths it,

That isn't how it gets earthed.

the wire is no longer where it should be and the appliance doesn't work.
That would get noticed.

But wont necessarily see the device unplugged
and it might well be a while before anyone
needs to use it and notices that it doesn't work.

With the current scheme you only need one fault.

But non faults can kill you because the RCD will protect you.

RCDs didn't used to exist,

But they do now, so it makes no sense to go for your hare
brained scheme now which doesn't allow earth faults to
be detected and which have no way of protecting people
from getting electrocuted when they happen.

so isolated mains would have been more sensible then.

Nope, which is why NO ONE world wide was
actually stupid enough to do it that way.

Even now, not everyone has them. I certainly don't. And I laugh at
people who have nuisance trips.

And they will laugh at your corpse when it kills you, and cheer.

The only problem is with a fault which results in the individual
ending up across the live an neutral with the current flowing
up one arm and down the other etc and that is very very
unlikely indeed and most of the time will trip the RCD anyway.

The RCD wouldn't stop that at all.

Corse it will because some current will flow thru the person to ground.

On Sun, 08 Nov 2015 23:15:15 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 22:06:11 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both
poles
(I'm calling them A & B rather than L & N) at the transformer
secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted incoming
didn't blow any fuse. Apparently the only fuse is about 800A on the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the substation,

Yes, we have that too and you can see them on the ones half way up the
power
poles.

The ones that sit on the ground don't have them visible, but they have
them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the
individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire from
the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is
now
at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it that
way.

But with my scheme you can only get a shock if there are two faults.

But there is no way to detect the initial earth fault,
so it will go unnoticed until someone gets a shock
and many won't be aware of the significance of that.

They're rare.

Not rare at all in fact.

And probably if a wire comes loose in the appliance and earths it,

That isn't how it gets earthed.

How does it then oh wise one?

the wire is no longer where it should be and the appliance doesn't work.
That would get noticed.

But wont necessarily see the device unplugged
and it might well be a while before anyone
needs to use it and notices that it doesn't work.

Most people notice when their washing machine won't run.

With the current scheme you only need one fault.

But non faults can kill you because the RCD will protect you.

RCDs didn't used to exist,

But they do now, so it makes no sense to go for your hare
brained scheme now which doesn't allow earth faults to
be detected and which have no way of protecting people
from getting electrocuted when they happen.

No nuisance trips with isolated mains.

so isolated mains would have been more sensible then.

Nope, which is why NO ONE world wide was
actually stupid enough to do it that way.

Even now, not everyone has them. I certainly don't. And I laugh at
people who have nuisance trips.

And they will laugh at your corpse when it kills you, and cheer.

Hasn't done it so far, and I've had several shocks in all sorts of different ways. Most electricians have too.

The only problem is with a fault which results in the individual
ending up across the live an neutral with the current flowing
up one arm and down the other etc and that is very very
unlikely indeed and most of the time will trip the RCD anyway.

The RCD wouldn't stop that at all.

Corse it will because some current will flow thru the person to ground.

Only if they are barefoot and outside.

--
When you want a man to play with you, wear a full-length black nightgown with buttons all over it.
Sure it's uncomfortable, but it makes you look just like his remote control.

"Brian-Gaff" wrote in message
...
Pardon?

Brian

Sorry Brian, I was alluding to the forthcoming argument between the brace of
trolls, Wodney and PHucker.
Rod Speed and Tough Guy no. 1265
aka the chuckle brothers.
Neither deserving of being given the time of day.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 23:15:15 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 22:06:11 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 21:33:32 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:44:45 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 08 Nov 2015 20:05:38 -0000, mick
wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The
replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply


On a "floating" mains supply as described you have to fuse both
poles
(I'm calling them A & B rather than L & N) at the transformer
secondary
for safety (there could be a transformer fault).

Fused? They don't fuse them sensibly.

They do here.

My parents' neighbour's roof burnt down because his shorted
incoming
didn't blow any fuse. Apparently the only fuse is about 800A on
the
transformer,

We have a fuse on each phase at the point of connection.
With a supply from the power line on poles down the
street, that is where the line from the street pole is
attached to the house, with massive great ceramic
blocks with a big fuse cartridge in a ceramic plug that
goes into the fuse holder and pulls out downwards.

Don't you have underground feeds?

Yes we do, and they have a fuse per line too.

We have a fuse for the wire coming from each phase in the
substation,

Yes, we have that too and you can see them on the ones half way up
the
power
poles.

The ones that sit on the ground don't have them visible, but they
have
them
too.

but that branches to several houses, with thinner cables!

We have a big fuse on each of those wires where it enters the
individual
houses.

Here, that's a 100A fuse right next to your meter. Hence the wire
from
the pavement into your building is unprotected.

and the wire going to his house is 100A.

Now, consider an earth fault after the fuse on pole A. Pole B is
now
at
line voltage to earth because neither fuse will blow (there is
insufficient current to earth on
pole B). In this situation it's very easy to get a fatal shock
from
pole
B to earth.

But you can already do that now, without it floating.

Nope, if the live is earthed, that will blow the fuse or breaker.

No, I meant you can get a shock from live to earth now.

You can with your hare brained scheme that no one world wide
uses too, when there is an earth in any of the houses that is
supplied
by that substation, with no way to detect that at the substation,
and it makes no sense to turn the power off to all those houses
fed from the substation even if you could detect it, and you can't.

That's why no one world wide has ever been stupid enough to do it
that
way.

But with my scheme you can only get a shock if there are two faults.

But there is no way to detect the initial earth fault,
so it will go unnoticed until someone gets a shock
and many won't be aware of the significance of that.

They're rare.

Not rare at all in fact.

And probably if a wire comes loose in the appliance and earths it,

That isn't how it gets earthed.

How does it then oh wise one?

Much more often damage to a cord or cable, oh stupid one.

the wire is no longer where it should be and the appliance doesn't work.
That would get noticed.

But wont necessarily see the device unplugged
and it might well be a while before anyone
needs to use it and notices that it doesn't work.

Most people notice when their washing machine won't run.

Only when they come to use it next, which may well be well
after the fault has occurred, and they don't normally unplug
it as soon as they notice that its not working any longer either.

And when the earthing is due to damage to a cord or cable,
it wont even stop working, it will carry on fine with all but
the worst damage to cord or cable.

With the current scheme you only need one fault.

But non faults can kill you because the RCD will protect you.

RCDs didn't used to exist,

But they do now, so it makes no sense to go for your hare
brained scheme now which doesn't allow earth faults to
be detected and which have no way of protecting people
from getting electrocuted when they happen.

No nuisance trips with isolated mains.

No trips at all, even when someone has just fried themselves.

so isolated mains would have been more sensible then.

Nope, which is why NO ONE world wide was
actually stupid enough to do it that way.

Even now, not everyone has them. I certainly don't. And I laugh at
people who have nuisance trips.

And they will laugh at your corpse when it kills you, and cheer.

Hasn't done it so far, and I've had several shocks in all sorts of
different ways. Most electricians have too.

And some end up dead too.

The only problem is with a fault which results in the individual
ending up across the live an neutral with the current flowing
up one arm and down the other etc and that is very very
unlikely indeed and most of the time will trip the RCD anyway.

The RCD wouldn't stop that at all.

Corse it will because some current will flow thru the person to ground.

Only if they are barefoot and outside.

Bull****. Plenty of grounds inside and you don't have to be barefoot either.

"Rod Speed" wrote in message
...
**** snipped

You pair of ****s need to get a room/**** off and type ******** somewhere
else.

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer. Using
an auto transformer to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

--
*If you ate pasta and anti-pasta, would you still be hungry?

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

Anything can be dangerous if you wire it up wrong. Don't.

--
I'm not a vegetarian because I love animals. It's because I hate plants.

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

Anything can be dangerous if you wire it up wrong. Don't.

--
Please note new email address:

On Mon, 09 Nov 2015 15:26:07 -0000, charles wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

--
A chicken crossing the road is poultry in motion.

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article , Tough Guy no. 1265
wrote:
Anyway, every time I've seen one of those yellow builders
transformers for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

yes because it's only one coil - with a tap somewhere near the middle (to
get 120V)

--
Please note new email address:

On Mon, 09 Nov 2015 16:46:00 -0000, charles wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article , Tough Guy no. 1265
wrote:
Anyway, every time I've seen one of those yellow builders
transformers for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

yes because it's only one coil - with a tap somewhere near the middle (to
get 120V)

I guess they're more for smaller step downs? Because most are like 240V to 12V, where the output needs more current so a thicker coil.

--
You know you've spent too much time on the computer when you spill milk and the first thing you think is, 'Edit, Undo.'

On Monday, November 9, 2015 at 4:41:37 PM UTC, Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

Cheaper, smaller, less excitation current (so less leccy wasted when current isn't being drawn from the secondary), better voltage regulation. Yes much less copper is used and a smaller core is needed.

Main disadvantage is that under fault conditions primary voltage can appear on the primary as they are not isolated.

They are used a lot on the high voltage side of the mains distribution networks.






--
A chicken crossing the road is poultry in motion.

On Mon, 09 Nov 2015 16:56:36 -0000, wrote:

On Monday, November 9, 2015 at 4:41:37 PM UTC, Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

Cheaper, smaller, less excitation current (so less leccy wasted when current isn't being drawn from the secondary), better voltage regulation. Yes much less copper is used and a smaller core is needed.

This:

Main disadvantage is that under fault conditions primary voltage can appear on the [edit: secondary] as they are not isolated.

Would make you think this:

They are used a lot on the high voltage side of the mains distribution networks.

Is a bad idea.

--
With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. -- Steven Weinberg

"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

Anything can be dangerous if you wire it up wrong.

Nope, double insulted is fine when wired wrong, at worst it won't work.

Don't.

"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders
transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

Corse they are, just one coil, stupid.

"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 16:46:00 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article , Tough Guy no. 1265
wrote:
Anyway, every time I've seen one of those yellow builders
transformers for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

yes because it's only one coil - with a tap somewhere near the middle (to
get 120V)

I guess they're more for smaller step downs? Because most are like 240V
to 12V, where the output needs more current so a thicker coil.

Anyone with even half a clue doesn't use transformers for those anymore.

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

That's what it means. The output winding has no reference to the input
one.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

A Variac is a variable voltage transformer. And entirely different device.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

Anything can be dangerous if you wire it up wrong. Don't.

If you could guarantee everything was correctly wired and used safely,
there'd be no need for additional safety precautions.

--
*It's not hard to meet expenses... they're everywhere.

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 09 Nov 2015 18:02:47 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

That's what it means. The output winding has no reference to the input
one.

It does on one end in the case of an earthed builder's one.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

A Variac is a variable voltage transformer. And entirely different device.

No, it's an auto transformer where you can move the tap. The coil is in the same configuration.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired up.

Anything can be dangerous if you wire it up wrong. Don't.

If you could guarantee everything was correctly wired and used safely,
there'd be no need for additional safety precautions.

Safety precautions don't tolerate incorrect wiring.

--
Advice given to RAF pilots during WWII:
"When a prang seems inevitable, endeavour to strike the softest, cheapest object in the vicinity as slowly and gently as possible."

"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 18:02:47 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders
transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

That's what it means. The output winding has no reference to the input
one.

It does on one end in the case of an earthed builder's one.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

A Variac is a variable voltage transformer. And entirely different
device.

No, it's an auto transformer where you can move the tap. The coil is in
the same configuration.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired
up.

Anything can be dangerous if you wire it up wrong. Don't.

If you could guarantee everything was correctly wired and used safely,
there'd be no need for additional safety precautions.

Safety precautions don't tolerate incorrect wiring.

Double insulated does.

On Mon, 09 Nov 2015 18:36:32 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 18:02:47 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders
transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

That's what it means. The output winding has no reference to the input
one.

It does on one end in the case of an earthed builder's one.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

A Variac is a variable voltage transformer. And entirely different
device.

No, it's an auto transformer where you can move the tap. The coil is in
the same configuration.

to give the 110v would work the tools - but could end
up with 240 on one leg of the output to ground if incorrectly wired
up.

Anything can be dangerous if you wire it up wrong. Don't.

If you could guarantee everything was correctly wired and used safely,
there'd be no need for additional safety precautions.

Safety precautions don't tolerate incorrect wiring.

Double insulated does.

Why do they call it double insulated? It's just insulated. Eg. plastic chassis.

--
I took my Biology exam last Friday. I was asked to name two things commonly found in cells. Apparently "Blacks" and "Scousers" were not the correct answers.

On Mon, 09 Nov 2015 17:52:06 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 16:46:00 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article , Tough Guy no. 1265
wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article , Tough Guy no. 1265
wrote:
Anyway, every time I've seen one of those yellow builders
transformers for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

yes because it's only one coil - with a tap somewhere near the middle (to
get 120V)

I guess they're more for smaller step downs? Because most are like 240V
to 12V, where the output needs more current so a thicker coil.

Anyone with even half a clue doesn't use transformers for those anymore.

I do if one is lying around.

--
They say that when a man holds a woman's hand before marriage, it is
love; after marriage it is self-defense.

On Mon, 09 Nov 2015 17:50:30 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Mon, 09 Nov 2015 15:26:07 -0000, charles
wrote:

In article ,
Tough Guy no. 1265 wrote:
On Mon, 09 Nov 2015 13:48:44 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Anyway, every time I've seen one of those yellow builders
transformers
for sale, it's referred to as isolating.

Of course it's isolating. That refers to the design of transformer.

Hmmmm, isolating from the mains perhaps. I assumed isolating was
completely isolated, as in floating.

Using an auto transformer

Oh is that what they're called, I call those Variacs. Very useful.

Vsriacs have a variable ouput. Autotransfomers can be fixed.

Seems pointless. Are they cheaper than two separate coils or something?

Corse they are, just one coil, stupid.

But you can take less power through it.

--
They say that when a man holds a woman's hand before marriage, it is
love; after marriage it is self-defense.