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14th Jan 2019, 07:17 AM #16
I disagree, but happy to hear your point as to why you think there is an absence of engineering principle in the standard. Have you read it? You can purchase it here
So... this was correct, now not so.
Machines used to be able to be certified using an under-rated plug, for the purposes of 'demonstration' by the retailer, or for machine setup. The Label to have the machine fitted with the supplied larger CSA cable and plug was to ensure that it was all above board.
The certification process now requires the machine to be sold in the same condition as it was presented for certification- so hence, most larger machines now have a large input cable and plug fitted.
The devil in the detail though- some machine suppliers simply don't get their machines certified, and sell the machine however they wish. This puts the consumer at risk.
Some of the more unscrupulous suppliers have massaged their stated duty cycle and iMAX values for their machines to sneak a machine in under the 15A iEFF rating to allow them to fit a smaller plug - essentially fudging the data to their own benefit. When this data is enetered into the calculation formula, it is in their favour. If you are like me and like the late 80's / early 90's japanese cars, it's similar to the power output 'gentleman's agreement' of a capped 290 HP that the GTR Godzilla, supra, and other hot cars of the day all made.
In the end of the day, there is no free lunch with a welder- you want to weld big, you need to supply big power.
The problem begins by our mate illegally modifying an appliance. Secondly, as a home owner, he probably should have also maintained or at least had inspected his home for faults, which if it was, circuit breakers would have been installed to the 21st century spec. If this was the case, they would most likely trip, and he'd be safe. So on the latter part, I think we agree.
The NZ argument though- that's an obvious straw-man- unless you want to provide some reputable per-capita stats to back it up?
Heck, if we lived in downtown Dehli, we'd just throw a wire onto the transformer, right?! I went there- you'd get a brown out every hour, and households would have transformer / capacitor units to smooth out the power to protect the TV/ computers etc from these spikes. I can't help but think every brown out was a short to earth thru some poor Indian bloke who found himself between the active and earth...
I for one, in no way resent the fact that we have a system that requires a licensed tradesperson to work on electrical installations. Could I do it myself- sure I could, but overall it's a safer proposition to have it within the scope of work of a professional.
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14th Jan 2019, 07:23 AM #17Most Valued Member
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14th Jan 2019, 09:09 AM #18Most Valued Member
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When did the rules change regarding supplying machines with undersized plugs for commissioning purposes? The machines that I have seen this on were not fly by night ebay specials,so I would be inclined to think that they would have been compliant and certified to the relevant AS. Cigweld is certainly doing it and I can find references in the Fabgear catalogue for 2017. Fabgear are quite open about it and state the fact in large print while Cigweld put it in the finer than fine print.
I cannot say that I have the same warm fuzzy feeling towards electricians. Despite what they may like to believe, they are not living gods, nor can they walk on water. I have personally seen two monumental stuff ups by two separate sparkies that could have caused loss of life. One was running a heavier cable to prevent excessive voltage drop on a pressure pump installation on a rural home, (why the previous sparkie didn't put in adequate wiring is another question I guess). The wire was run and connected to the board with a new D curve breaker and the pump commissioned with good results. That was until quite by accident the old wiring was found shoved into a bundle in the corner of the pump shed, still very much live and with lovely bare wires waiting to zap someone. The second instance was when my workplace was putting power onto our second shed. Previously we had run extension leads as required, but this was both tedious and unsafe. We enlisted the services of a sparkie and while we had to keep a close eye on what they did, (why don't sparkies listen???), the work was completed - or so we thought. Running a single phase plasma cutter the circuit breaker tripped. When I went to reset it, I noticed two things. Firstly, the breaker was only a C curve and we had requested D curves due to running welders etc, secondly, the plastic plugs covering filling in where extra breakers could be fitted were missing and a very live bus bar was easily within finger poking distance. We reported this to said sparkie and he said that he'd "try to get there some time to fix it, just don't stick your fingers in there till I do." The final straw was when Tech Safe called in to do an audit of the installation, they found that there was no earth connected to the new shed whatsoever. Based upon these experiences, I really fail to see how I could do worse.
You seem pretty sure of your facts and you made the statement that you had done a bit of this before Commander_Keen. What is your actual background and prior experience with matters electrical? Our membership here comes from many diverse areas and there is a lot of knowledge and combined experience that you may be able to add to.
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14th Jan 2019, 09:15 AM #19Pink 10EE owner
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14th Jan 2019, 09:15 AM #20Most Valued Member
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Check this link from the land of the long white cloud. https://worksafe.govt.nz/managing-he...ectrical-work/
It sounds like you may be able to work from a Sub Board onwards, but not from the initial board.
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14th Jan 2019, 09:34 AM #21Most Valued Member
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Looks like you're right Karl. Lucky buggers.
Chris
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14th Jan 2019, 09:36 AM #22Most Valued Member
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14th Jan 2019, 10:56 AM #23Most Valued Member
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All the disclaimers mentioned, I have a short piece of cable that I use if required ( 300mm ) with the appropriate fittings that I have had for over 10 years and used when required,as a non electrician I would say use it,the only exception that I would consider is if you intended using it for extended periods ( more than 20 mins constant welding ).
Based on what Bunnings have I would think 20 mins would be well above there duty cycle.
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14th Jan 2019, 12:37 PM #24
Well this seems to have fired a few people up! lol.
Full disclosure - I'm a sparky who works for the local electrical distribution company, I inspect new switchboards and, all being well, connect them to the mains. I also do other stuff though I cannot walk on water, sometimes I have lead feet etc. I may be out of date with the latest rules as well given there has recently been a new version of AS3000
In general, I agree with OPs opinion, non electrically qualified people doing their own electrical work can lead to less than optimum outcomes. Sometimes, having qualified contractors also leads to less than optimum outcomes. Some are really good and others don't seem to have much of an idea. Guess that's the same as in any other field. Electrical work covers a wide gamut of tasks and some sparkies are very good at a few of those tasks and somewhat less good outside of those.
Commander Keen you included this in your original post "This includes the 'single 15A GPO on a 15A circuit' rule. Circuit protection can and does fail under higher loads than they are designed for"
Once upon a time AS3000 specified how many 10A GPOs (points in electrical talk) could be connected to a single circuit. This got changed several times to end up "as many as you like" keeping in mind the likely hood of circuit breaker protection operating i.e. nuisance tripping. I am paraphrasing all of this. i.e. the circuit relys on the protection operating to prevent overload. I also understood that you can now put one 15A GPO on a general power circuit. This may have changed???
I am seeking understanding from you about "Circuit protection can and does fail under higher loads than they are designed for". Circuit breakers do not immediately trip when the load goes above their rating, rather the time to trip is inversely proportional to the current. Thus say a 15 amp breaker may take quite some time to trip at 16 amps of load. So are you saying that if a 15A breaker is cycled to 16A, but for not long enough to trip, and such cycling is on a regular basis it is likely to fail? If that is what you are suggesting then I would consider that 15A circuit breaker "not fit for purpose"!! Also a pile of burnt out circuit breakers may be proof that the electrician did not make the connection to the wires tight enough thus causing a hot joint to form. The only way to be sure that load caused a circuit breaker to fail is to measure the load after the failed breaker has been replaced. Even then the breaker should trip to clear what it sees as a fault rather than be damaged. Perhaps you can provide some more clarity around you comment?
R.C. - Pretty sure the electrical standards (there are quite a lot, AS3000, AS3008, AS3017, AS3077 to name a few) are based around a mixture of engineering standards and practical input. The replacement of a single outlet GPO with a 4 outlet GPO doesn't really change anything in that the circuit is still reliant on the protection to trip before there is any damage. Thus you could put 100 GPOs on one circuit in your shed, you still can't get more than 20 Amps total. There would be no "nuisance trips" as they would all be "major PITA" trips as you went about finding the fault, turning equipment off to allow other equipment to run etc. BTW those 4 outlet GPOs are great just wish they were cheaper.
Just to clarify, wiring should be selected to handle the load of the circuit, voltage drop and loop impedance considerations along with how the wiring is installed then an appropriately rated protective device chosen. Maybe this is what you meant?Equipmenter.... Projects I own
Lathes - Sherline 4410 CNC
Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.
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14th Jan 2019, 12:51 PM #25Pink 10EE owner
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Gold, the colour of choice for the discerning person.
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14th Jan 2019, 01:25 PM #26Most Valued Member
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14th Jan 2019, 02:48 PM #27Most Valued Member
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Molesting children. Wow, that escalated quickly.
Perhaps the contacts in a 15A GPO have a greater contact area than those in a 10A GPO? There has to be some reason why 15A GPOs exist.Chris
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14th Jan 2019, 04:14 PM #28Diamond Member
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The contacts for Active and Neutral are the same, it is just the earth pin that is larger on the GPO
With a 20A GPO the contact pins for Active, Neutral and Earth are the same size as the earth on a 15A plug.
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14th Jan 2019, 04:37 PM #29Most Valued Member
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I have pondered the same question and the answer I came up with was that the sole reason for their existence was to act in a way similar to an unleaded fuel nozzle, I.E. to prevent the incorrect socket being used for higher rated equipment. Other examples exist such as 10, 15 and 20A 3 phase plugs. All use the same diameter pins and the same layout, however the shaping of the block holding them means that a 20A outlet will accept the lower rated plugs, but a 10A outlet will not accept the 20A plug. A similar case exists with 32A and 50A 3 phase outlets. This would have made sense back when 15A GPO's were installed on their own dedicated circuits but has lost some relevance now that it seems that they can be installed in multiples at the sparkies discretion. Having decomposed both 10A and 15A GPO's, I can find no difference in their construction internally.
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14th Jan 2019, 05:25 PM #30Most Valued Member
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