Anyone know what the official position on pushwire cable joiners for permanent installations is?
I'm thinking, for example of a loft light, where you might take a permanent feed L,N,PE into a surface-mount switch plate and then on to a batten holder or fluorescent. The switch plate has terminals for the live, the backbox has a terminal for the PE and you've got to connect the neutrals together somehow.
Wago Lever, one better than the pushin type and based on their long proven DIN rail version. They come in 2-way 3-way & 5-way, available on Ebay UK for one (bizarrely no-one does a mixed pack).
They handle flex from very small right up to 4mm, 7-strand (6491X) to
2.5mm, and solid to 2.5mm. Rating is 20A, although UL listing is for
32A, I've used them on heavy loads without issue.
The Wago ones above are ASTA certificated - at 0.75mm2 to 2.5mm2 solid/
1.5mm2-2.5mm2 stranded to 400V/24A. I am assuming that is "400V-nominal-rms" and is good for 3-phase 400V supplies (which have a peak phase-phase voltage up to about 622V of course), but this is not clear from the Wago website.
The team *does* seem to agree that these are acceptable for BS7671 installations, but any idea what/where the "official rubber stamp" for this product is?
Is there an IET recommendation, or a British Standard? Who, for that matter, decided wire nuts were not acceptable? They used to be commonplace in the UK.
With this way of wiring lights seemingly becoming more common it might only be a matter of time before the manufacturers bring out switches with a pair of linked neutral terminals built in. This could be applied to 1-way, 2-way and intermediate switches.
The UK aversion to 'wire nuts' is Interesting. I first encountered them here in Canada some 54 years ago and they are almost universally and commonly used in domestic and other wiring. As a rough estimate there are likely a couple of hundred in this house which we built 40 years ago and can't think of a single problem due to a wire nut. In fact the only electrical replacements have been a couple of circuit breakers, several duplex outlets (in particular two on the basement work bench that of course got a lot of use plugging/unplugging tools which were replaced last year because one was cracked and the other slightly chipped. Maybe a couple of single pole light switches (I swear the interior of several we used were identical to the then in use UK variety) and rated for maximum 15 amps 120 volts RMS. Which of course a lighting circuit rarely if ever is. Three line voltage electric baseboard heating thermostats (one changed for decorative reasons) the rest are going strong after the 40 years. Not a single electric baseboard heater has failed, although the overheat switch on one of them did go open for some strange reason and it was a year or two before noticed that one of the two baseboards in that room not heating! Typical wiring back then, as in this house is/was 14AWG for 115/120 volt lighting with 15 amp breakers and 12AWG 115/120 volt wiring for the various duplex outlets. Electric heating wiring is 12AWG 230 volt again with 20 amp breakers. So the method is to use a larger number of radial circuits. Ring mains not used anywhere AFIK. Larger appliances such as an electric cooking stove, tumble clothes dryer, etc. are wired with heavier gauge wire, usually with heavy plug/ sockets each from a dedicated circuit breaker. The hot water 'tank' (cylinder is wired 10AWG rated for 30 amps at 230 volts although each of the two 3000 watt elements are wired 'flip flop' first heating to top of the tank then flipping over to heat the bottom. However the 10AWG and 30 amp breaker allows both top and bottom to be paralleled for faster recovery; occasionally convenient when one has five extra visitors staying and needing showers, extra dish washing etc. All wiring is copper. We have for convenience provided some 230 volt duplex outlets at work benches to cater for some 230 volt tools, including a 1953, 230 volt Wolf drill, the bench saw and some 230 volt cordless battery chargers. Also a dedicated 230 volt single 30 amp welder socket in the garage. We even have a British style switched 230 volt, plus ground, 13 amp outlet. Probably illegal here! To occasionally plug in anything that comes by with that type of plug. The single pole switch only switches off 'one side' of our 230 volt; but the whole thing is beyond a two pole fused switch above the work bench that kills everything in the workshop except ceiling lighting every time we leave. With all this wiring and as mentioned wire nuts are used extensively and despite the higher amperage necessitated by the half-voltage (a typical 115 volt toaster can draw 8 to 11 amps) have had no problems whatever with them. Using wire nuts where stranded wire is being joined to solid (ceiling light fixture) may take a little more care, to avoid cutting stands of wire; but seems infinitely more preferable to those little tiny screws in chocolate blocks?
For the record: Solid Cu.cond. ....sq.mm. Rating.Amps.
14AWG 2.08 15
12AWG 3.31 20
10AWG 5.26 30
But probably what one is used to and both the 2 Wire, 230 volt, Live + neutral and earth and the 3 wire 230/115 live - neutral - live with ground as used in North America both seem very sensible systems.
IET formus do not agree they meet BS7671 for inaccessible connections, contrary to what the manufacturer claims.
They were never commonplace for mains wiring. They were used for things like doorbells, speaker, and aerial cables, so they were around.
The UK predecessor to the choc block looked exactly like a wirenut, and I think that's where this confusion arises. I have many old wiring books with pictures of junction boxes wired up with these, but even back as far as 1930's, they all have a grub screw in the side to properly clamp the conductors - they aren't wirenuts.
They became illegal in the 1970's when all wiring accessories needed to be covered by an appropriate BS, and they weren't. However, they weren't in use at that point at all, and never had been seriously. That's not to say you won't find them - I found one in a kitchen professionally rewired in 1972, and presumably botched by someone after that date who found one in the bottom of their bits tin when moving a socket, and thought "oh I'll use that".
Andrew - I reckon you're just not old enough !! Ceramic wire nuts - and I didn't recognise that as the correct term for them, we just called them screw connectors, were still being used extensively when I started doing wiring in the 50's and 60's.
- UK 32A Radial not permitted with 4.0mm 7-strand (6242 or 6491X)
Wago will accept 4.0mm Fine-Stranded (Flex) which is technically permitted for a 32A radial if a) all terminals are suitable for flex or b) suitably prepared (bootlace ferrules). Most older DNO chaps would have a fit, but BS7671 17th does permit it - however since 4.0mm flex is much more expensive than Flat-Twin-&-Earth it is of academic value only.
US (UL) rating is 20A...
- US 20A due to wire size limits, 2.5mm limit on solid & 7-strand
- "they have only been tested & certified for 4.0mm Fine".
"Wirenuts" were common in the North even into the 1950s probably by "old sparks", less so in the South. I think they relied on 2 factors - cables of that era were a) tinned & b) multi-strand. a) Tinning excludes corrosion when strands are twisted inside a wire- nut so achieving a gas tight joint. Canadian wire I believe has tinned conductors, UK circa 1950s PVC Flat Twin & Earth (FTE) had bare single copper conductors, UK circa 1950s PVC Flat Twin (no earth) retained tinned multi-strand conductors. b) Multi-strand conductor must be essential for wire-nut twisting action without conductor breakage. Again UK after circa 1950s moved to solid conductor for 1.0 1.5 2.5mm sizes which would be more likely to fracture in a wirenut.
Another issue with wirenuts is one of direct contact with the wirenut terminal, they were commonly used outside of an enclosure which to the unwary crawling around a dark loft could be an unpleasant surprise. UK lighting circa 1950s used 3-strand tinned which is mechanically pretty weak and of remarkably small cross section - it does not take much to fracture the conductors which could result in overheating.
Scruits, IIRC. Very common with lead-sheathed cable installs. I have a bagful retrieved from an old installation, jealously guarded. And I remember a textbook describing them as being useful, and IIR *that* C it would have been Modern Wiring Practice by Steward & Stubbs in c.
OK, we need to be clear on which series we are talking about.
The 273 series is rated at 18A, 24A or 32A @ 400V
The 2273 series is rated at 24A @ 450V
The 773 series is rated at (24A or 41A @ 400V) or
(24A or 42A @ 550V)
I'm still not clear whether the "400V" rating is good for UK 3-phase, which could be as high as 440V rms. I am sure it would be ok in practice, but why doesn't the manufacturer say so?
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online catalogue | Contents | Ternminal Blocks and Connectors | installation connectors | push-wire connectors for junction boxes
Finally, what is the argument for "not suitable for inaccessible"?
Oops. My comments are re Wago 222 Series - orange lever type. Strip wire 10mm bare end, lift lever up, insert wire, close lever. This link might work or it might not -
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Regs require connections to remain accessible unless crimped, soldered etc. Push-in type do not give me confidence, Lever involves a hand operation, neither are a crimp in terms of "cold weld" although Lever goes a lot closer to it.
Hey; I had forgotten the 'wire nut' style with a grub screw! Although have used the odd one. Very useful. Have seen then with both slotted and hexagon (and I think) square Robertson headed grub screws. All made of brass. One use for those grub screw type has been to fix broken spots in coiled resistance wire heater coils. A temporary repair but which in some cases have lasted an incredible length of time. We fixed one of the heating coils of my neighbours clothes dryer some five years ago because 'it was not getting as hot as usual and was taking longer to dry the clothes'! They still seem to be using that dryer! When using them that way on hard resistance wire hand cranked the brass 'set/grub' screw as tight as possible without stripping it. Seems to work!
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