Here is a list of all the postings Phil Whitley has made in our forums. Click on a thread name to jump to the thread.
|Thread: Safety of phone chargers|
t was a politicians son or daughter that died due to shoddy electrical work carried out by a builder that brought about PART P. Which in my opinion is a good thing, but would be better if it was ENFORCED, and not just a money making scam for the powers that be, and jobs for the boys.
Correct Paul, it was. but the reason (she) was killed was not shoddy work, but the removal of the requirement that "all extraeneous metalwork must be earthed" from the regs. A metal framed partition had been fitted and wired for lighting, then plasterboarded, and a pb screw had damaged a cable. If the metalwork had been earthed, the rcd would have tripped immediately the circuit was powered up, but it remained on, and the partition frame became live and went unknown till the unfortunae victin was mopping the concrete floor next to the partition. I had the report of this occurence sent to me by electrical review, and wrote a piece for them commenting on the problem highlighted by this unneccasary tragedy. The part p boys claimed that it was caused by a lack of proper testing, whereas it was actually caused by lack of proper earthing! A test is only valid on the day it is done, a properly fitted and earthed installation is always safe.
There you go Duncan!
Of course there is another factor in all this which I have not mentioned. I served a five year apprenticeship and spent three years at technical College to gain my qualifications, you may not believe this, but today you can go to a "college" tip up about £3500 and become a certified domestic electrician IN 5 WEEKS!! Is it any wonder that standards have fallen through the floor?
Not off topic at all Bill, for a known off topic thread thief like me! After installation, but before connection, ring continuity is one of the tests done to check that all is well, and we used to attach a sticker to the consumer unit which stated
" This installation should be periodically checked and tested, and a report on its condition obtained, as recomended in the IEE regulations for the wiring equipment of buildings"
Under normal usage, if installed correctly, there should be no possibility of a failure of continuity in the ring, however, with sloppy installation and second fix, it does happen, which is why the regulations have beefed up the testing regime. The problem you have pointed out is that the circuit continues to function even if continuity has failed on one side of the ring, whereas in a radial it would stop working, and thus demand attention. The actual hand tool work done during the second fix of an electrical installation is of vital importance to the overall function and safety of any installation, and as quoted by Ian Hewson above "Any installation is only as good as the person installing it" and "Leave it safe or leave it OFF" were drummed into us as trainees!
Absolutely right Mike!
Interesting! Can't see a reason for banning rings, and 2 pole MCB's must make for massive CU's, but I can see the point about the earth wire, but you can go back to the days when even some lead covered cables had a seperate tinned earth wire, (although most used the lead sheath as earth) and there has never been a problem, at least with rewirable fuses, but given that the MCB provides much coarser over current protection, you can see the logic. The size of the earth wire in some T/E has been increased, due to the fact that under fault conditions the earth wire may become a current carrying conductor.
When I first did my training, the reg for domestic ring installations was " Any number of sockets on the ring, and any number of sockets on a spur, so long as the number of spur sockets did not exceed the number of ring sockets, and the whole did not serve an area bigger than 100 sqm (?) That sounds like a lot, but I think that was the figure. Over the years, the ring final subcircuit has proved itself to be very safe indeed, as both incidence of electrical accidents in the home and domestic electrical fires caused by the wiring, as opposed to connected appliances has fallen steadily since the early sixties, and is now virtually flat lining! With the advent of MCB's and as witnessed by the new fire regs covering consumer units (they ARE catching fire!!) I fear this will not be the case for much longer. Really bad regulations, and really bad "solutions" . Consumer units catching fire? best find out why (we alredy know) and stop it happening? Nah mate, to diff, just stick it in a fire proof box!!
Having spent time in France, some of the wiring I have seen and experienced, especially in the older Parisien hotels, with flickering lights and crackling switches, made me cringe and one of my wifes relations has had several houses in rural France where a fault in the house could blow the fuse on the utility pole, and there would have to be a call out to fix it! Just remembered, I have a coil of white 1.5mm, blu/bro with an insulated g/y earth in it, wonder if it has made the trip across the channel!
Right, so I have finished being Mr Bloody pedantic now, and one of the hats I wore during my varied electrical career was as MD of LN Communications, which brought internet services(and still does, under a new name) to various remote national park and other areas using wireless tech, One of the units we used to install had a wall wart PSU, and many of our customers started complaining of "a funny smell" in the area of the wifi adapter. One of my network oppos reported that he had gone to an installation to find that when he unplugged said wall wart, the live pin stayed in the socket, and the plastic just crumbled in his hand! We started fitting new ones, and sent the faulty ones back to the importer for replacement, I cant remember the exact numbers, but it was somewhere between 50 and 100 failed within the warranty period. This illustrates the problem with the direct plug in wall wart, which has no replacable fuse. These were protected electrically internally, but not thermostatically, the temperature rise was caused by poorly fitting undersized pins on the plug in part ( a very common problem) and allowed the wall wart to slowly bake itself without causing any circuit protection to actiivate, untill all the plasticiser was gone and the whole thing disintegrated. We installed these in places where they could not be covered, so the heat dissipated, but they were VERY dangerous, and it is a miracle that none caught fire. My own daughter had a habit of falling asleep with her phone on charge with an extension lead and the wall wart under the duvet with her, and there has been one local case , and one other reported(and probaly many more) where covered wall warts have set fire to bedding and the like without activating over current protection because the current was not excessive, even though the heat was! In short (when have I ever said anything "in short" the OP's fears are well founded!
Dave Thank you sir!
"As you can see this means that a rewirable fuse is far safer than an MCB," should have added there, "provided it has been rewired with the correct rated fuse wire"
and theres the rub!
also note that a rewirable fuse ALWAYS fails safe!!
Edited By Phil Whitley on 22/04/2019 18:24:23
In the interests of electrical correctness, ther are one or two things in daves post I must take issue with, because we are all here to learn, everyday is a school day, and safety matters in electrical installations.
Radial circuits were the way power for connected appliances was distributed before the ring main came into being. By the late 60s, when I was serving my apprenticeship, we were rewiring all the old TRS and VIR wired installations, removing radial circuits and replacing then with ring mains. It is also wrong to say that in a radial, each socket is wired seperately back to the consumer unit, each radial is a string of sockets, and uses larger cable than a ring, otherwise you would need a consumer unit with enough ways in it to have a seperate one for each socket, but the radial has one major disadvantage, and that is that in a ring circuit, current is equal in all parts of the ring. In a radial, the first piece of wire between the CU and the first socket carries most current when all sockets on the circuit are in use. This is a major reason why radial circuits were scrapped and replaced with ring circuits, and whilst I know they have been reintroduced, there is no good electrical reason to do this (if you know of one, please let me know!)
I know of no disadvantages of the ring system, and it is generally accepted that the UK wiring system is (or at least, used to be, more later) the safest in the world bar none. Most of the world still does not use shuttered sockets, which were introduced in the UK in 1947.
The point you make about the plug fuses being there to protect the wiring and not the appliance is partly semantic, and electrically incorrect! The fuse or MCB which protects the ring (or radial) is the coarse protection, the fuse in the plug is the fine or selective protection, and although no fuse will protect against electrocution, it is there to isolate the appliance in the event of a fault, thus stopping the risk of a localised fire at the appliance by isolating it from the ring. Take the instance where a double insulated vacuum develops a fault and begins to draw excessive current. There will be no tripping of the RCD, because the current in live and neutral are the same, and let us assume that the fuse in the Vacuums plug is 13A, with a fusing factor of about 1.2 for a cartridge fuse. When the current rises to 15.6 amps, the plug fuse will rupture, and disconnection will occur. Now let us look at the same situation from the point of view of the ring main, it only sees a current flow of 15.6 amps, but if additional load on the ring takes the total load on the ring to more than its protection (fuse or MCB) then the whole ring will be dissconnected, before the cables in the ring even get warm. there is no situation in an otherwise correctly wired installation where the ring will overload to the point of ignition. Also note in the above example a vac should be fused between 5 and 10 amps! I do know however, and have read in publications which should know better, that "the plug fuse is not there to protect the appliance" and semantically, it is not, it is there to prevent temperature rise in the appliance getting to ignition level, it is there for safety, but it does NOT protect the ring main from overload, that is what the fuse or MCB in the consumer unit does.
You could argue that the ring main is even more suited to todays low current applications, but please note that the immersion heater should NEVER be put on a ring main!
Now to my main point, as I mentioned above, fusing factor! I am now retired from the electrical industry, but I have installed many consumer units and distribution boards that use MCB and RCD protection, all done without going too deeply in to the technical side of MCBs. Indeed I have just completed the installation of the 3 phase and single phase distribution boards in my own workshop.In the older Wylex and similar rewirable fuse consumer units the fuse has a "fusing factor" which is given as a figure used to calculate at what current the fuse will actually rupture and isolate the circuit. For rewirable fuses, it was originally set at 1.5, IE a 10A fuse would blow at 15amps, and we did experiments in the college lab to prove this was the case. Since my original training, that figure has been increased to 1.8, and even 2 in some cases, won't go into it here as I am already long winded but looking at the actuall tripping currents for MCBs, which I had assumed would be much closer to the rated current and thus provide "better" protection I find to my surprise that the following applies.
Type B 3 to 5 times rated current.
Type C 5 to 10 times rated current
Type D 10 to 20 times rated current
Type K 8 to 12 times rated current
Type Z 2 to 3 times rated current
As you can see this means that a rewirable fuse is far safer than an MCB, in that it will isolate a circuit reliably at a lower current, and when you add to this the fact that an MCB DOES NOT FAIL SAFE, you can understand that the new (new new corrected reprint) book of latest regulationd now requires all consumer units to be metal clad and installed in such a manner that an internal fire cannot escape the enclosure. I am really glad to be out of an industry where good engineering has been thrown to the wind, and regulations, which used to be made by senior engineers, are made by wet nosed uni graduates and electrical equipment manufacturers. rant over!
|Thread: Making Holes in Copper Sheet|
may not be suitable for your purpose, but if you drill a smaller hole for a length of threaded rod, and the select a couple of sockets from a socket set, the smaller having the external diameter of the hole you want, and able to fit inside the larger with a reasonable ammount of clearance, assemble them onto the threaded rod with one socket on either side, and tighten the nuts thus forcing the smaller socket through the sheet and into the inside of the larger one, you will find you can form a very usable socket into a flat sheet. I have done this in steel, aluminium and copper. Anneal it first! you could even turn up a couple of dies on the lathe, but I have found that sockets work just as well, provided you can find the correct diameters.
|Thread: 'War Department' (arrow) Marking|
Lots of history here, it is VERY old! https://en.wikipedia.org/wiki/Broad_arrow
|Thread: Dialect expressions|
When I moved from Pudsey, in W yorks, to Bridlington, I thought they were rum uns, but when we moved to Langtoft on the east yorkshire wolds, 3 years later in 1963, I couldnt understand a word of what some of the broader folk said, as they spoke a dialect based on old norse, and still used a lot of old norse words, and sentence construction. hence a greeting was, "Wa noo mi lad, wets thoo a deein of? spoken in a high pitched nasal brouge at 100 miles an hour, and I just stared back at him not understanding a word he had said!
A gate post is "an ord yat stean" Bridlington gate becomes "Brig yat" A path or pavement is a "trod" etc etc. I remember one ocassion at a pig farm when a large boar escaped, and the farmer, a bow legged old boy in his eighties came out to see what all the fuss was about. I was told "ees a bad un keap outat road on im" When one of his lads asked what they were going to do, he said, "assl get im gannin, an thoo get yon big mell, and wen he comes, thoo nap im ower't skorp wit mell as ard as thee can" The lad picked up a lump hammer (mell from mjolnir, Thors hammer), and when the old boy, who was a bit unsteady on his feet chased the boar round the corner, the lad wacked it over the head with the "mell" and it went down like a shot, it was quickly rolled into the bucket on the front of a tractor, and deposited unceremoniosly back in its pen.
We used to have some serious winters, on one occasion we recorded -22 overnight in a greenhouse, and the old boys would come out with "thoo watch thisen, its reet sleip ower yon tha knaws" ( be careful it is slippery over there you know) but always pronounced sleap as SleeeIP. odd till I found out that Sleipnir was Odins eight legged horse that could gallop over ice without losing its footing! when you got to know these old boys, they were wonderful people, salt of the earth types, who are sadly, like the accent, all but gone now. Although I still have my workshop at Langtoft, it has become a dormitory village, it has no shops, the pub and school have closed, and it is an altogether more humdrum place for it. I do miss them all, they were great people.
|Thread: Machinery Directive and CE marking|
Here is an interesting though Robert, for the purpose of this document, what is the definition of "safe". Is that "safe under all circumstances", is it "not likely to cause an accident under normal use" then of course you would have to define "normal use". Why would you build a machine that you knew to be unsafe? Is it possible to build a machine that is safe in all circumstances? I would posit that it is not possible. It is still possible to have an accident on a lathe, even if it meets all the HSE requirements, so is it safe or not? What is the definition of "Responsible person", As I said, a buck passing excercise, have you ever wondered why HSE do not inspect a factory before it is put into use? I will tell you, if they had inspected and passed it as safe, they would be responsible for that safety, as it is, they neatly pass the buck to "the responsible person", and only inspect the workplace after an accident has happened, in order to decide who was at fault, ie apportion blame, and collect revenue, non of which is paid to the victim. CE compliance does not assure safety, it merely shifts the responsibility for safety. The above is a very badly drafted document, that any reasonably competent lawyer could drive a coach and horses through unless there are clear definitions of what constitues "safe" and "responsible person". "i.e is CE compliant and section 7 says " is this wording part of the document, or are they your words?
Edited By Phil Whitley on 07/04/2019 18:23:30
If it is "pretty clear" Robert, why are you asking the question? You most certainly CAN import goods which are not CE marked, what you cannot do is offer them for sale , as importer, you are responsible for providing CE assurance if you resell. All equipment put into use in a workplace must be safe, however, this is only incidentally under the CE legislation, first and foremost is the HSE requirement. You can build or import items that are unsafe (should you want to), who would stop you? As has been said in this thread the mechanism and manpower required for enforcement does not exist, and the only requirement under CE is that you posess paper work that "assures compliance" If it is only you using it in a private workshop, it is no ones business but your own, and the risk ends with you. much of the electrical equipment from Bangood etc does not comply with CE, ( watch John Ward and bigclivelive on you tube to see some of it being tested) but it is sold worldwide, and anyone can order from them and import effectively into the EEA without certification. Whether that is a wise thing to do is another matter, but it does not change the fact that the mechanism to prevent this happening simply does not exist. My point is that CE marking does not prove safety or compliance, or that the goods have recieved any testing independantly of the manufacturers, it merely assures that the manufacturer, and the importer are in possesion of documentation that states that the item in question meets the required CE standard. Yesterday, I fixed my mothers vacuum cleaner, it is made in China, badged Morphy Richards, and some importer somewhere in the UK probably has a dusty shelf with a load of CE compliance paperwork on it pertaining to this product.The problem is that the actual product is a piece of shoddily made plastic trash that is barely able to perform its said function seems to be irrelevant. Your fawning deference to this supposed standard is rather odd, As I said before, we used to set the standards for the world, and we have let those standards slip terribly. CE is not a system to maintain or raise standards, or to ensure safety, it is an elaborate buck passing exercise where the responsibility for the safety of a product is shifted from the EU back onto the manufacturer, or the importer, which means, in the event of an accident, unless you can interest your (now virtually non existent) trading standards dept, you will end up suing the importer or manufacturer yourself to get compensation for the damage caused by their shoddily made goods. Good luck with that. It seems that you actually WANT to live in a police state where everything and everyone is "compliant" You should watch Terry Gilliams brilliant movie "Brazil". It is a very clear illustration of the type of world the EU is trying to create with this type of legislation. The sooner we are out the better, and then we can dump CE and set real standards and start refusing the piss poor quality we get from the far east, via European legislation, at the moment.
|Thread: Motor Gland|
looks like 3/4 conduit, which means, no you wont get one anywhere unles you can find an old sparks like me who has some in a tin under the bench! If you have any long established electrical engineers near you, try them!
|Thread: Colchester Triumph 7.5" (Round Head) Lathe|
Yes it might! that one is different to the student, but it does show a key which holds the gear in question to the second shaft, which may well be the cause of the failure! edit, just looked and I have a copy of that manual as well, but it is 11meg so it would be best for the op to download it himself!!
Edited By Phil Whitley on 07/04/2019 12:32:05
|Thread: Machinery Directive and CE marking|
SOD, Again For What It's Worth: the CE Marking Association and the EU both say there is no such thing as a 'China Export' trademark. Anyone who believe the lower mark means 'China Export' is misled, it appears to be an urban myth.
Well they would say that wouldnt they. The Chinese Export tale is just an excuse to dump goods on the European market which appear to carry a genuine CE mark, but are actually untraceable back to an original manufacturer, and have no paperwork compliance assurance available. realistically, you can only prosecute a manufacturer for non compliance if you know who and where he is! When was it first noticed that the accuracy checked paperwork included with Chinese machine tools was A) all identical, and B) bore no relevance whatever to the machine it was packed with? "When sleeping dragon wakes, whole world will tremble" may refer more to aggresive commercial techniques rather than outright aggression.
|Thread: Colchester Triumph 7.5" (Round Head) Lathe|
Clive, as far as I can see the layout in the parts list for the mk1.5 student is the same, as is the lever layout on the outside of the box. The ratios might be different, but I think it is essentially the same as mine. There appears to be a pin 5649 that anchors the gear to the second shaft, and also a double key, and a single key on the spindle which anchor the gears to the spindle. I would suggest that the failure of either would cause the sudden onset symptoms he has. At any rate, it looks like the second shaft at least will need to be removed. I have a pdf student manual, but it is resisting my attempts to send it!
first thing is that the gear lever is in the wrong position, it should face upwards, and move from the 10 oclock position to the 2 oclock position, there is a pin through the second shaft which I think keys the gear to the shaft. I have a pdf manual for a roundhead student, which is essentially the same gearbox, I will see if I cam PM it to you.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.