I'll also add:
I have wired up my own extension cords from very early on (
certainly early enough to set off the "child safety" brigade's alarm bells, but I had my father who was an electrician check that the earlier ones were done correctly so thankfully, no-one got hurt) firstly out of curiosity and then for "fun" for a while (although I later became more pragmatic about it, so my most recent two were done using salvaged appliance leads, with the rewireable sockets I had on hand fitted onto the cords still with their original moulded plugs) and used 90°C rated flex for most of them because I could obtain it easily. It's not noticeably stiffer than the 70°C (or 75°C to Australia's version of the standards; in this day and age of globalisation, of course, flexes typically bear both the European and Australian approvals on one unit) type, allowing for the normal variability in flexibility of PVC from different makers and manufacture dates - so I can't imagine the difference being noticeable with solid or 7-stranded building wires, then. And if you pick the "right" combination, you can find a round (even 3-core!) cord that's as or more flexible in
all directions as a flat cord made more recently by
the same manufacturer is in the plane it flexes most easily (and no, I'm not cheating by comparing an ordinary-duty flat cord with a light-duty round cord - not that I would see fit to, given that most of the flat cords are light-duty with the ordinary-duty ones being the exception, while ordinary-duty round cords are common enough; those in this comparison are both ordinary-duty), so it's an embarassment, really. The manufacturer of the cords in question is
Well Shin, for the record (and for your information, they can be found attached to the Australian version of the PSU for the Nintendo Wii U* - and presumably the versions for the other markets too).
*Nintendo's classic efforts to make their systems hard(er) to break would explain why they chose the ordinary-duty cord, even though a light-duty cord would be legal for the relatively small unit (as H03VVH2-F is a bit fragile and it doesn't help that the end connectors typically have poor strain-relief). (They already used such a cord on the PSU for the previous Wii, although that time it was from a different manufacturer and noticeably more flexible; the US version, by the way, is equipped with NISPT-2 recalling from a photo I saw before, and I'd bet on VCTFK on the Japanese version although I haven't seen that one. Their official PSUs themselves, incidentally, have some of the best build quality I've seen in small SMPS - although they are not multi-voltage which is a bit unfortunate, and the fixed cords are quite backwards today, now 45 years since IEC 320 was initially published.) Incidentally, I currently have just one other flat ordinary-duty cord for myself - this one with an Australian plug to an IEC C7 socket, and it too is more flexible than the new Well Shin cord. To put that into perspective, I have over 200 total cords in my stash now, of which 25 or so are with C7 sockets, although it's been a while since the last substantial bunch I was given - and the "hoarding" has, consequentially, mostly stopped at present.(To be clear, I'm using the terms "light"- and "ordinary"-duty in relation to cords with the 300/300V and 300/500V ["downgraded" to 250/250V and 250/440V in Australia, although that change appears to be merely political and the heavy-duty cords, curiously, were up-rated from 450/750V to 600/1000V] category voltages, respectively. Both inner insulation and outer sheath thicknesses differ - so ordinary-duty cords are more durable than light-duty, but somewhat stiffer given the same quality of PVC. I know this to be official usage in the relevant standards, IEC 60227-5 [and 60245-4 for rubber cords] and AS/NZS 3191. H03VVH2-F and H03VV-F are not available with 1.0mm² or larger conductors, nor are they allowed on major appliances even with lower current drain.)
Overall, the European standards make much more sense than the North American ones do, to me at least. The "singular" category voltages given for the North American and Japanese/Taiwanese cable types are, to me, an obvious example of dumbing-down of the rules; the "split" voltage ratings for the European (and Australian) cables make perfect sense when you remember that there are two layers of insulation between any two active conductors in the cable, spreading the voltage gradient - and really, anyone who doesn't get this (quite simple) concept shouldn't be working on anything 3-phase to begin with, thank you very much.
AS/NZS 3191 seems to have adapted an already good standard to be even better, for the most part (although I'd personally prefer to stick to the more conservative harmonised voltage rating for heavy-duty cord, and here they have yet to update the braided cords to not expose the inner wires when kinked; this is the standard that defines the braided cords with XLPVC inner insulators, by the way, although elastomer-insulated ones like in Europe are also permitted); one of its more notable additions is PVC cord suitable for intermittent operation ("for an average of 500 hours per annum" quoting from a pirated copy of the standard - not that I would be paying the asking price just for my personal use either way; this system that forces you to pay up-front for the standards documents is a broken system, really - at least,
I would surely go broke if I tried to buy all the standard documents of interest to me) up to 105°C (known as "V-90HT"), like with much hook-up wiring (I must say, by the way, that it
is a bit of a trap that the hook-up wire - especially UL AWM 1015 [heavy-duty, 600V working] and its double-insulated version, UL AWM 1617 - is just marked 105°C with no indication that
continuous usage is still limited to 90°C; this is somewhat akin to only listing the best-case ampacity on building cables sold in UK hardware stores, isn't it?).
(A bit off-topic, but another thing I eventually found out as a result of my extension cord DIY among other items is that HPM's products of the past 15 or so years are terrible; at the time, I was predominantly using HPM's plugs and sockets because, again, they were easy to get - from the local Bunnings Warehouse - and because they're an old Australian brand that most people still seem to trust. Well, so much for that, as the transparent version of their model 7P extension socket once used a particularly low-quality clear PVC that not only discoloured to that yucky yellow-brown quite nastily - with no appreciable provocation, mind you - but also reacted with the cord's insulation, turning it brown - insane! (Clear PVC is, generally, more troublesome than opaque PVC, but Clipsal gets their transparent ones right too.) Then they changed it subtly, somewhat fixing the plastic issue but this time messing up the cord grip dimensions, so it won't hold onto the cord [H05VV-F3G1.0 or the equivalent] that it's supposedly designed for, no matter the position of the plastic securing nut! Only 1.5mm² (ordinary-duty - there aren't any ready-made Australian extension cords that I'm aware of using the equivalent of H05VV-F3G1.5, although I've obtained the 90°C Australian version in orange also from Bunnings and used it for two extension cords for, well, no particular reason at the time although I know now that it will stay noticeably cooler under the full 10A, which would no doubt be beneficial at times in the often hot Australian climate - and in the interest of reducing voltage drop, I would recommend it for cords longer than 10m anyway [and, indeed, 2.5mm² flex for carrying 15/16A beyond 10m if you can obtain it and a compatible plug and socket pair, and/or again to reduce the temperature rise]) cord will be held firmly by that last revision I tried, but this is still wrong. My grandmother's current dwelling is wired with mostly the HPM "Excel"-range switches and outlets, and their cover plates have yellowed quite obtrusively - although, conspicuously, the gridplates are still white; in comparison, the lone Clipsal 2015 (single outlet) there really stands out in its still spotlessly white beauty. Some of those HPM outlets also take rather excessive force to remove the plugs from, and the covers can even break at their clips when trying to remove them. I also have a few 6-way power-boards they made that clearly couldn't stand up to even modest UV exposure...yeah, I think those are quite enough reasons to justify avoiding them now. At this stage, I'd take one of the better imports over recent HPM any day of the week - speaking of which, one outlet in the bathroom here has a notable history:
- Originally a Clipsal 2015, which (along with most of the other original switches and outlets in this house) was in (I think) the "Desert Sand" colour option. (Subsequently, in the year 2010, the remaining Desert Sand switches and sockets were replaced with the usual White Electric because the originals clashed with the current paint colours.)
- I wanted to charge two electric toothbrushes at once, without having to continue using a double-adaptor (ugly things that they are). Courtesy of Dad's stuff, I was able to get a Clipsal 2025 double outlet to install - that simple swap I could already handle fine.
- But then some "handyman" had a crack at moving it over to the left to make room for a new mirror, of course in a horribly botched manner with a potentially extremely dangerous result (it was "supported" by a wood-screw with an oversize head, into the plasterboard alone, only on the left side, resulting in the outlet eventually being able to be pulled right out of the wall with little effort at all).
Well, at least I knew that Bunnings would likely have a selection of mounting hardware with which I could make a robust repair thereafter. (This stage was after Dad lost his battle with cancer - so I was on my own, not that I needed assistance by then.) I got some suitable screw-plugs to fit to the wall, and now for the interesting part: The outlet, made by Deta who popped up here quite recently. As any electrician here in Australia will immediately notice, their "6000" series is a dead ringer for the ever-popular Clipsal 2000 Series - in fact, it's so close that the surrounds can be interchanged between the two, more-or-less. (Deta still have yet to replicate the multi-gang surrounds, though.) I'm not sure if Clipsal actually mind that much, though - given that the two brands aren't sold alongside each other (Clipsal refuse to sell their products to the general public, although at a point 10-12 years ago the white 439 [10A plug], 438 [10A extension cord socket] and 418 [10A side-entry plug] could be found repackaged by Ring-Grip, so I used a few of them) and the line is well over 20 years old - but intellectual property issues aside, Deta even appears to have made a small improvement to the clip-on parts; even on Clipsal's stuff, the surrounds can be bloody hard to pull off at times, depending on the manufacturing tolerances - although they at least don't usually break in the process. If you're curious to know more about it then I'd be willing to post some photos, along with further general comments. The little-used corner mounting holes really came in handy in that situation, and although I was forced to omit the lower right mounting point, the end result still feels solid enough.And I wouldn't want to finish off this post without this quick-fire question: For 2-core flat cords, do you prefer the sheathed types (NISPT; H03VVH2-F and H05VVH2-F; VCTFK) or the "figure-8" types (SPT, H03VH-H, VFF etc.), overall? To sum up the basic pros and cons of each:
Sheathed- Looks nicer in-situ (IMO)
- Inner insulated wires are colour-coded, so are easily differentiated at a glance
- While the sheath may occasionally break, at least you survive so long as the inner insulators remain intact
- Can't mount a clamp-on ammeter for current measurement without cutting in and accessing the inner cores
- If you fail to clamp the sheath properly, it can pull back - this may expose the inner cores (this is particularly irritating for Australians, as local plugs designed for these cords are stupidly hard to find - well, HPM's side-entry plug will work with it, but I've already told you what I think of them...)
Figure-8- Gunk can accumulate in the "valleys" between the cores
- Sometimes you get a stripe for coding, sometimes ridges. Not quite as prominent as the brown/blue or black/white combo.
- If the insulation breaks, you're in serious danger
- A clamp-on ammeter can easily (and quite safely) be mounted simply by splitting the two cores apart
- A bit quicker to connect, with no "stripping off the sheath" step
And if a flex in the figure-8 overall form but with 2 discrete insulation layers (the inner layer providing the colour-code) was made, it would provide most of the "best of both worlds" (except aesthetically), albeit at slightly higher cost.
(For the unitiated, as I understand it the insulation on figure-8
mains leads is designed to the "reinforced insulation" standard - and it probably does meet the dielectric strength requirement at least, comparing the SPT variants to the inner insulators of SVT, or the 300VAC light-duty hook-up wires.
Note, by the way, that you should not take the military-standard rating of 600VAC for some hook-up wires as indicating applicability to mains voltage, as those are only for intermittent duty and making the insulation significantly thinner than needed for a 300VAC safety agency rating (which tends to go with a 1kVAC military rating!) will also reduce the breakdown voltage below the minimum needed to withstand surges on the mains supply - which also explains why almost no mains cables are rated for less than 250V even in 100-120V countries.)
So I've added two polls for you to answer; the second is about if you too have noticed the trend to stiffer cords, as I noted before.
