Why do EVs not use the full 3.12kW from a mains socket?

Probably more likely years although the modern socket may well melt first. Modern ones are nowhere near as well made as the older ones were.

A typical UK 13A rated standard fuse to BS1362 will support 20A indefinitely according to the specification! I know from bitter experience that they will support 26A for around 3 minutes since that is how the church tea ladies destroyed one of the VH extension leads.

A nominal 3A fuse will take nearly 5A before it blows in a fraction of a second. The low current ones are somewhat steeper protection.

The fuse is intended to protect against shorts and cable cuts they are pretty sloppy as current limiting devices. And they get damn hot at 13+A.

Now all of our VH extension leads now have thermal cutouts so that if you use them still all coiled up and plug in two kettles at the far end it does not self immolate. The fuse ultimately protected but only after the whole thing had melted internally and live touched neutral or earth.

:-))

Ok, good to know. Not the normal kind of fuse I know of.

You remember the Spectrum? Well, the power supply had a thermal fuse. Once of those blew off, and they asked me at the student residence to have a look. I had never seen one, and couldn't get one at the component shop. I don't remember now if I did finally found one, or replaced the unit with a wire or a standard fuse.

We thought, how funny Britons are, installing thermal fuses in gadgets :-)

There's more to it, but the main player on this point is that on a radial a bad connection becomes an immediate fire risk, whereas on a ring it creates no fire risk.

no need. If fitted and high powered enough they'd go on their own circuit. People do use portable ac occasionally, it runs on a plug with no difficulty.

there are some houses that use plug-in space heaters. If you exeed 7.2kW continuous you'd expire before the circuit tripped.

a trivial load. If you made an 8kW hair iron you'd catch fire fast.

I can't think of any plug-in that exceeds 3kW intermittent. 32A provides over 7kW contiuous, much more intermittent. How much more is a matter for debate, but double is fine.

we tend to put a socket anywhere it's likely to be used. Leads don't drape across walkways. It doesn't require 1 per 6' for that.

snip

if one does you've got a fault. Pdiss is 1 watt at rated i.

Most plugs & sockets are fine at 13A, but there have occasionally been ones that didn't meet that requirement, so many appliances now stick to 10A, as it's then one design for multiple countries.

we were comparing rings with radials, not 240 with 110. I explained upthread the prime reason for better ring safety, but it's not the only one. And yes, 240 is safer than 110, assuming proper safety is applied. Fire is a much bigger killer than shock.

it is when it's a ring. Are you entirely familiar with ring circuits? If so you'll know why they're more reliable.

switches are not required. They're almost universal for safety, convenience & energy saving. Plugs are now £1 a piece here, probably more than in the US but they are a much safer design. Double sokcets (switched) £1.60 each now, down to about 1 pound each in a multipack.

almost all. Seriously there's not much US wiring practice that's allowed here, mostly on safety grounds.

US uses 5mA GFCIs iirc. UK uses 1x 30mA per entire circuit.

Nuisance trips can occur on 1st generation RCDed installs, where they were mandated prematurely, and used 1x 30mA RCD per entire house!

There is plenty of lousy housing, I agree with hat. There is also plenty of excellent housing, which mostly does not land in the dubious hands of estate agent management.

I suggest you read the specification of your local fuses carefully then.

Lower current fuses do tend to blow PDQ at around 2x their nominal rating but the 13A ones are remarkably resilient.

Automotive fuses with low melting points have a much lower voltage drop and dissipation at any given current.

I even remember the call centre in an attic where CS students earned pin money answering repair calls - at least until all the common modes of failure were identified and then replaced by clueless script droids.

A form of built in obsolescence. Just about all UK mains powered kit has a fuse in its plug with the possible exception of electric shavers.

The one time thermal cutout fuses in fan heaters have prevented a lot of fires from units that have been obstructed or knocked over.

What bad connection? Bad connections in house wiring are virtually non-existent, other than when aluminum wiring was used 50 years ago. If this were a problem your redundant connection is only protection until a bad connection develops. You have no way to know your protection is compromised.

How high is "high"? I see home where virtually every room has a window AC unit. "A" unit will run on a circuit ok. It's trying to fit the several units that becomes a problem.

You have very limited thinking. Again... imagine one in each room on a cold winter night. I know people who do this. They think individually heating the bedrooms saves money over heating the house.

I love the fact that you think the problem with this is tripping the circuit breaker, rather than the fire hazard.

LOL Look them up sometime.

In the US, we take fire safety seriously. We can't draw double the rating of a breaker without it tripping. I think I see why UK electrical safety is a myth.

LOL You don't know where they are needed until you try to plug something into an outlet, and it isn't there. Or maybe the furniture arrangement is mandated by the floor plan. I have a living room with furniture that's not against a wall. I added outlets in the floor.

Copper oxidizes, and nuts and bolts can become loose.

...

That's not possible in my country, as we typically clean the floor with a mop and water.

How does a ring save copper?

So chop out the "another radial back" bit and save copper.

In my house, there is not a radial run per outlet. Most runs hit multiple outlets. We have roughly 8 loads per breaker, something about like that. We don't have 100 breakers.

I thought one concept of the ring was to avoid overheating at a bad, high-resistance junction. So every wire has to stand the full load, and the ring increases the worst-case run length downstream of a bad connection.

Do ring circuits have a ring impedance monitor, to detect those bad connections? I suspect not.

if you think that you know jack about domestic wiring. Bad connections are why the UK banned wirenuts in 1955. They're why all sockets use screw connections, not poke-ins.

it's ok /after/ a bad connection. Radials aren't.

It's called an EICR. Even without one, 1 bad connection tolerance is much better than zero.

enough to not be a good choice for the ring, obviously.

Again, if installing that much they get their own circuit.

Whoosh. 7kW of heat continuous is fairly intolerable.

You won't create a fire hazard by plugging too much in. The cable has enough ampacity to be fine until the mcb/rcbo/fuse trips.

Why? I've seen plenty. Your suggestion that they exceed a circuit's capability is fantasy.

Kitchens here are often all on one ring circuit bar the cooker. Greatly exceeding 32A for a few minutes is routine. It's not a safety issue, it's how they're designed to work.

I'm not sure what your complaint is. It simply isn't a problem with modern wiring. Outdated setups do lack sockets, we had way less electrical stuff in the 70s & before. It's unusual now to encounter inadequate sockets.

With respect a ring cannot fail to share the load both ways, you can't plug over 7kW into one socket. The cable has the ampacity to handle real life. To call that not sensible is failing to grasp how they work.

If you sketch a house layout with its sockets, it's obvious right away that a ring layout uses less cable. The ring goes all round the outer wall. A sigle radial would save a tiny bit of length, but have to be thicker. Multiple radials use much more.

When first used in the late 40s, rings were created by linking 2 existing 15A sockets (which were on radials), and adding as many sockets to it as wanted. This was practical for the diyer, uses the minimum of cable & did not involve accessing fusebox wiring.

there is NO length downstream of a bad connection.

no, nor do radials. I daresay the future will involve a lot more detailed monitoring than today's setups.

Both the USA and UK either require or recommend Arc Fault Circuit Isolators (AFCI) for some circuits such as those for bedrooms.

They will detect arcs and disconnect power to that circuit to reduce the chance of a fire or smoke due to a bad connection.

kw

We require GFD outlets within some distance of water fixtures, and around concrete floors like garages. That's all. I have outside weatherproof-covered outlets that for some reason don't.

Ours in the kitchen false trips sometimes, like when I make whipped cream or puree sauce with my immersion blender. Minor nuisasnce.

On Monday, 17 April 2023 at 18:29:13 UTC-7, John Larkin wrote: ...

an AFCI breaker can also detect series arcs caused by bad connections, not just parallel arcs or ground fault.

They have been required for many years in the US for bedrooms with more of a residence being included with each revision of the rules. Commonly the same breaker will also include GFD/GFCI functionality.

kw

Twice the current carrying capacity for a given wire diameter provided that the ring remains intact. Parallel resistors and all that.

Way cheaper than a star configuration of single cables to each socket where everything has to go back to some common node or other.

Be aware that KC is a well known thick UK troll who is just pulling your chain. If he was any good at it he would not have to post so much!

There is no such thing as a false trip in that sense - only one that takes the total leakage current above the trip set point.

Other ones I have seen include:

Old VH water boiler after a period of no events. It would trip the very first time it was switched on and then mysteriously self heal. Turns out the hard water/air bubble in the tiny hole in the element was enough to get it through a entire session but it had in fact failed.

My neighbours bread maker did something similar although it was rusted to hell by the time it failed. Heating elements and mixer motors seem very prone to corrosion causing an insulation breakdown failure.

Self healing ones are particularly hard to find since all you get is a report that it happened but immediate testing shows "no problem".

The one that used to take our kitchen lights circuit down annoyingly was failure of a classical spotlight creating a ELCB or over current trip when the bulb blew. LED spots don't have that problem at all.

Come take a look at the new meeting up places in the internet............

⠀⠀⠀⠀⠀⠀⠀⠀kohtumispaik2.freehostpro.com/a.php ⠀⠀⠀⠀⠀⠀⠀⠀kohtumispaik3.66ghz.com/a.php ⠀⠀⠀⠀⠀⠀⠀⠀kohtumispaik4.medianewsonline.com/a.php ⠀⠀⠀⠀⠀⠀⠀⠀aaaaaaaaaaaaaaaar.medianewsonline.com/firstpage.php ⠀⠀⠀⠀⠀⠀⠀⠀themostconfortabletalkplace.medianewsonline.com/a.php

See You there, man..........