Electrical safety — room for improvement?

[LongRunner]

My take on it is that:

• The only way for mains outlets to be child-safe (aside from placing them out of their reach) is for them to have internal shutters blocking the insertion of foreign objects into the power-carrying contacts; the idea that plug-in covers will provide protection is nothing more than wishful thinking, at least with flush-mounted sockets. If the plastic they are made of is brittle, they can also snap their pins (especially with thin flat pins as on the Australian and North American plugs), leaving them in the socket and rendering it unusable.
• I have no idea who thinks it's OK for the same old plug/socket system to remain in use in North America. Bare live and neutral pins only a few millimetres from the edge of the plug are not safe enough, nor are extension-cord sockets that make it easy to misinsert the plug in such a way that one of the power pins is in the slot with the other hanging off the side and waiting to zap someone (by way of the current passing through the appliance). What's even worse is that some Japanese power cords have a very similar 2-pin plug, plus a separate earth wire exiting from the plug with a fork lug on the end, that must be manually attached to a binding post in the outlet…
• The old incandescent lamp sockets are also of great danger to those who insert their fingers into them. Personally, I think they should have been banned and replaced with something safer decades ago, but people have just too much resistance to changeover.
• Adding insulating sheaths to the thin flat pins on Australian plugs has, rather noticeably, worked against their mechanical strength, and bending the pins too far can break the insulation (which is usually, if not always, a hard plastic) off. Then again, I guess that's just what happens when you add a safety feature on as an afterthought…
• In terms of physical construction, the sheathed unshielded mains cables could be said to be Class II (double-insulated), and shielded flexible cords (seldom-used, but I have a few) would be Class I (as the shield is earthed). I don't want "figure-8" (e.g. SPT) cable on the mains, as only one insulation layer between the mains and the outside world is just asking for trouble, at least in my view.
  Additionally, I have seen the sheathing on light-duty flat cord occasionally fail at strain points. Permanently attaching any mains cord to an expensive item is not sensible, nor is permanently attaching a light-duty mains cord to anything (IMO). Unfortunately, many CRT TVs did attach a light-duty flat cord directly to the set, and not just the small ones, either. Personally, I think that light-duty cord is only just acceptable with the small IEC sockets (C1 with tinsel-wire, C5 and C7 with normal wire).
• To guard against overloading, a cord with a socket at one end should use cable with at least the current rating of the socket, and if the combined current rating of multiple sockets exceeds the rating of the main plug, a circuit breaker (or otherwise fuse) with the rating of the main plug should always be used. In Australia for example, normal power outlets (and most extension cords) are rated to 10A, but power circuits generally have 2.5mm² cable and 16A MCBs; power boards/strips here contain a 10A circuit breaker, but doublers are usually unprotected, so can overload extension cords with ease if abused. I believe the system used in much of Europe is that both MCBs and outlets are 16A, and extension cords there (whether single- or multi-way) are built to carry all of that.
• The problem with the "Schuko" plug/socket used in much of Europe, aside from not distinguishing between live and neutral, is that Schuko plugs will fit into various sockets without making the earth connection. The somewhat similar system used in France among other places with an earth pin in the socket only allows the plug to fit one way, but the actual polarity is not consistent, so it might as well be unpolarised anyway.

I know of a shuttered IEC60320 F-type panel outlet if you want it — Schurter 4721 (screw-mount)/4723 (snap-in). Although the 4721 has a rounded-rectangle outline in contrast to the usual more hexagonal type, both types mount as normal. They do cost more than the regular type, but safety is priceless, really. The mechanism used is that the shroud on the E-type plug opens the shutters before the L and N pins enter their slots; it seems impossible to securely shutter the cord-end socket (C13), unfortunately (and with the C1, C5 or C7, there's clearly no way a shutter mechanism will fit).

And, of course, there's that death-trap presented by the Y1 capacitors in most Class II switching supplies to signal circuitry…

[c_hegge]

I agree with you for the most part. The trouble is that it would be a real problem, though, with adopting a new standard is just how many millions of premises would then have to be re-wired with new outlets.As far as the government is concerned, the cost of doing so would be too high when most of the safety issues mentioned can be negated with a little common sense (Then again, you can hardly call it common these days...)

[LongRunner]

…one IEC E plug sacrificed to the WHAM! test. Specifically, in order to determine just how tough the shrouds on those things really are, I deliberately took a cord and hammered on the shroud. It actually put up quite a fight (taking several blows to break), which I find very respectable in the face of this world of stuff that breaks too easily. Comparing these to the Australian pin-insulation effort would be like comparing a video-game character (ever fallen into lava and survived, let alone only a quarter-heart of health down?) to one of us; there's no contest as to the tougher of the two. That's reinforced insulation for ya.

And, well…when it comes to damaging power cords, I have reserves. The same could not be said for a life. As for the aftermath, as this cord is whitish, and I had another black cord with a white Clipsal 418 (the old one, with non-insulated pins) attached, I took the 418 and wired it onto this cord. That other cord will likely be fitted with a rewireable E plug the next time I obtain a bunch of parts (which will also include, among other things, 8 (probably) C13 sockets to attach to what are best described in their present form as "death cords" — but in the meantime, I have a good deal of preparation to do). The result passes my "push-pull" clamp strength test*, so is deemed a success.

*Simply hold the connector or other item (e.g. in-line switch) firmly in one hand, then grab the cord and attempt to alternately push and pull it with the other. If the cord budges, the clamp has not been properly tightened or the cord is thinner than the clamp is designed to hold onto.

My assessment of the safety of several plug types is:

AS/NZS 3112
+ pins spaced well away from the perimeter
+ modern 10A (and some 15A) extension sockets have shrouds
− pins can be bent, breaking their insulation (as mentioned before)
− 20A version still lacks pin insulation (why?)
Overall safety rating: 6/10

BS 1363
+ mandatory safety shutters (from the beginning!)
+ very solid construction
+ insulated L and N pins since 1994
+ each plug has its own fuse (though this is necessitated by their use of high-current ring circuits)
− loophole in the standard that enables shutters to be defeated on some power strips
− plug is of a shape that tends to lie on the floor with the pins pointing upward (ouch!)
Overall safety rating: 9/10

CEE 7/4 (Schuko)
+ recessed sockets
− no L/N polarisation
− plug fits into various unearthed sockets (as mentioned)
Overall safety rating: 5/10

IEC 60906-1 (created as a projected "world standard" for 230V outlets, but so far only used in South Africa)
+ recessed sockets and insulated pins
+ mandatory shutters
− 2-pin version not polarised
Overall safety rating: 9/10

NEMA 5-15
+ at least the earth is connected in a reasonable manner
− still no pin insulation, and often little spacing between the pins and the perimeter of the plug
− many extension cords and adapters enable insertion of a plug with one power pin in the socket and the other accessible
Overall safety rating: 2/10 (the Japanese plug with a separate earth lug gets a 0/10)

IEC 60320 family (not used as wall outlets, but an interesting comparison)
+ recessed inlets, and plugs with nearly indestructible shrouds
+ very elegant handling of temperature ratings and insulation classes (in C13—C18 and C19—C24)
− no shutters except on select F outlets
− not keyed for voltage
Overall safety rating: 7/10

NOTE: E is the line plug in IEC 60320 that resembles the C14 inlet and F is the outlet that resembles the C13 line socket (though they are often referred to using the C-sequence anyway). In the same manner, I is the plug based on the C20 inlet and J the outlet based on the C19 socket. There are comparable plug/outlet couples based on C5/C6, C7/C8, C17/C18, and C23/C24, though those are rarely seen.

In case you're wondering what happened to C3/C4 and C11/C12, those were (apparently) for Class 0 appliances (had they been Class II, they would have merely been redundant with C7/C8 and C17/C18), rated at 2.5A and 10A respectively and both polarised. I have found no indication that they were actually used, though.