On Sun, 15 Jan 2017 16:26:39 -0000, trader_4 wrote:

On Saturday, January 14, 2017 at 4:53:16 PM UTC-5, James Wilkinson Sword wrote:
On Sat, 14 Jan 2017 16:21:37 -0000, trader_4 wrote:

On Friday, January 13, 2017 at 5:32:57 PM UTC-5, James Wilkinson Sword wrote:
On Fri, 13 Jan 2017 21:38:15 -0000, trader_4 wrote:

On Friday, January 13, 2017 at 4:23:27 PM UTC-5, James Wilkinson Sword wrote:
On Fri, 13 Jan 2017 21:16:45 -0000, trader_4 wrote:

On Friday, January 13, 2017 at 3:32:40 PM UTC-5, James Wilkinson Sword wrote:
On Fri, 13 Jan 2017 19:53:48 -0000, trader_4 wrote:

On Friday, January 13, 2017 at 2:01:02 PM UTC-5, James Wilkinson Sword wrote:
On Fri, 13 Jan 2017 01:40:22 -0000, wrote:

On Thu, 12 Jan 2017 23:16:47 -0000, "James Wilkinson Sword"
wrote:

Aren't the outlets also protected at 10a?

No, but the plug itself on each appliance has a fuse from 1A to 13A depending on the appliance.

That is actually not a bad idea.

It's an obvious idea, don't your plugs have fuses yet? You can plug anything into an outlet, if it's a 13A outlet, your 0.5A table lamp doesn't have its cord protected against fire from a short.

If it's a decent short, it will greatly exceed the breaker rating
and trip instantly. If it's a short just right to consume a lot
of the current on the circuit but not trip it, eg a 12A short on
a 15A circuit, then you have that potential with all the wiring anyway
and we live with it and it does not appear to be a major cause of
fires. We also require arc fault breakers on many circuits now,
eg those in the living areas.

What are you talking about?

Reality, the way thing are.


A 1A cord may only take 10 amps through it during a short, and catch fire. Yet the 15A breaker won't trip.

Never said anything different. But a direct short will produce enough
current to trip the breaker, ending the problem before the cord can
heat up. Happens all the time. Stick a screwdriver in a light socket
and it causes a current that trips the breaker right away.

As I just said, the resistance of the thin cord won't let enough pass to trip the breaker.


BS. Just stop. Typical lamp cord wire will easily carry way more
than required to quickly trip the 15A circuit breaker, for a short
duration. What do you think the resistance of a couple meters of
lamp cord is? And if you don't believe it, go stick a screwdriver
in an unfused lamp socket and see.

And all shorts have no resistance of their own of course....


That shorts have resistance of their own is part of the whole
point. You can't have it both ways. First you argue that a short
in a lamp is going to create a fire from the lamp cord if it's not
fused. Then you claim the short limits the current because of it's
resistance.

It could easily limit it to anywhere between 1A and 15A, overloading the wire but not tripping the breaker.


Yes, that's theoretically possible, but the wire will not heat anywhere
near enough to create a fire. Do the math.

It's "maths" with an S you Yankee moron. Let me explain. P= I^2 R. The heat from 15 amps in the wire is TWO HUNDRED AND TWENTY FIVE times greater.

And just like with that cord, if there is a partial short
in a branch circuit that produces a current under the breaker limit,
it can start a fire, without tripping the breaker. According to you,
you Britts have all your receptacles on one 30A circuit. What happens
if you have a partial short that results in a current of 10A?
You have ~2.5KW, which is more than enough to start a fire. Yet you
apparently live with that.

Fire can only start if the current is higher than the wire carrying it can take.

That's absolutely false. A piece of paper on an electric stove proves
it. In the real world, fires start from bad, loose connections, from
arcing, etc.

But heating the whole wire is far far worse.

The whole point is that if the lamp is shorted, say by inserting
a screwdriver in it, there will be a high current that exceeds
the 15A, 20A circuit breaker, tripping it almost instantly,
*before* the wire can get hot. Even if there is some odd short
that takes the current to just under the breaker limit, it
will will not generate anywhere near enough heat in a lamp cord
to create a fire. If you understood basic electricity, you could
do the math to see that you're wrong.

A wire that is meant to take 1A will get 19 squared times hotter at 19A. That's very hot.

No, it;s not very hot. If you did the math, you;d stop embarrassing
yourself. Resistance of 18g lamp cord is .02 ohms per meter. Put 20A
through it and you get a whopping 8 watts, distributed over a meter
of wire. That isn't "very hot", nowhere near what it takes to start
a fire. Where is a fire likely to actually start? Where the wire
is damaged, at bad connections that overheat or arc, etc. And those
fires will start even with 12g wire on a 20A circuit.



Every wire should be fused at the limit of that wire. I can't believe you guys are stupid enough to have 1 amp cord protected at 15 amps.

I can't believe you're so stupid period.

Thanks for proving my point that you're an idiot. Your reply has no information in it whatsoever.

No, clearly the problem is that you can't understand or just ignore
the information
provided. As exemplified by your stupidity on claiming concrete
is an insulator. Everyone
here provided you with overwhelming info from credible source, eg
code authorities that cite concrete encased electrodes as one of
the preferred earth grounds, yet you just ignore it and drone on.
Now you're doing the same dumb thing again.

I have a multimeter, I know it's an insulator. But then my concrete isn't dunked below the water table like an electrode. We were discussing concrete slab under a house, which will not be even damp, or you'd have a very soggy carpet.

Again fool, look up concrete encased electrode.https://en.wikipedia.org/wiki/Ufer_ground

"When homes are built on concrete slabs, it is common practice to bring one end of the rebar up out of the concrete at a convenient location to make an easy connection point for the grounding electrode.[4]

The Ufer Ground is an electrical earth grounding method developed during World War II. It uses a concrete-encased electrode to improve grounding in dry areas. The technique is used in construction of concrete foundations.
During World War II, the U.S. Army required a grounding system for bomb storage vaults near Tucson and Flagstaff, Arizona. Conventional grounding systems did not work well in this location since the desert terrain had no water table and very little rainfall. The extremely dry soil conditions would have required hundreds of feet of copper rods to be inserted into the ground in order to create a low enough impedance ground to protect the buildings from lightning strikes.


You;re like a compass that constantly points in the wrong direction.
Pretty much whatever you say, we know it's wrong.



--
An old black-and-white photograph of a man milking a cow was sent to a photo-finishing company.
The man was sitting behind the cow, and all that was visible of him were his legs and feet.
A note accompanying the order read: "This is the only picture I have of my great grandfather. Please move the cow so I can see what he looked like."