Opinion - Your letters

Feedback: Your letters

Hazard of blanking plugs

Moulded plastic blanking plugs to fit 13A socket outlets to BS1363 Part 2 are widely available in the UK and even encouraged by safety agencies.

Since its introduction in 1947, BS1363 has required all socket outlets to be effectively shuttered. In the current standard, paragraph 13.7 states: 'The construction of the socket-outlet shall be such that when a plug is withdrawn from it, the current-carrying socket contacts are automatically screened by shutters.' Paragraph 9.4 states: 'It shall not be possible to introduce a conducting device through the earthing socket apertures(s) of a socket outlet in such a manner that there is a risk of making contact with any live conductor, with or without insulation.' Some of the best designs exceed requirements with shutters that additionally require two pins to be inserted simultaneously into the phase and neutral sockets to open the shutters. If the blanking plugs acted as a useful supplement to this safety system there would be little objection to their use. However, young children are very curious about their surroundings and very imitative. I have seen a 15-month-old successfully plug an appliance in and switch it on. It is not unreasonable to assume that the children whom these blanking plugs are intended to protect would find it possible to withdraw them and reinsert them in the inverted manner shown in the photograph, so exposing the live contacts of the phase and neutral sockets.

It is quite likely that the open holes would raise the child's curiosity, encouraging experimentation and possibly fatal consequences. The IEE was a major contributor to the drafting of BS1363. As its successor, I believe the IET has a duty to challenge any practice which compromises its successful safety features. I would advocate that the IET, as a professional body, should bring this danger to the attention of the Health and Safety Executive, and instigate an immediate ban on these blanking plugs and extensive publicity to discourage their use. It may be difficult to explain this to users who have limited or no technical knowledge, a challenge and responsibility for the IET, but this is definitely a case where nanny does not know best.

Peter M Munro, CEng MIEE,Barnhill, Dundee

How EMC defies legislation

Arthur Moore (Feedback, December 2007) asks: "Surely there is a fundamental requirement under EMC legislation that equipment shall not be susceptible to interfering signals?" We all wish that it were so, particularly those of us inside hospitals. The relevant standards for medical electrical equipment have a requirement for immunity to certain electric field strengths depending on the equipment application. However, these are not sufficient to protect against interference by mobile phones or radio handsets held right next to medical equipment. Sadly this has not prevented the general public now believing that it is OK to use mobiles everywhere inside a hospital. Electromagnetic interference is a complex physical phenomenon, hence it should not come as a surprise that it defies attempts to legislate it away or regard it as an old issue.

Peter Cook, London

Defence from the clones

I was interested to read about the new approach to personal identification numbers and the brief history of the cash dispenser in the December 2007 issue of Engineering & Technology ('Grid expectations'). There was a third system, in addition to the Chubb and Barclays machines, the first of which was installed in Croydon a month or so after the others. This system was developed for the Midland Bank, as it was then, by a small company called Speytec. It used returnable magnetic cards and had all the user features of cash dispensers in use today apart from note counters, but then none of the early machines had these.

It is interesting to note that all three systems had anti-cloning measures. As you say, the Barclays system had cheques impregnated with radioactive material, the Chubb system had three non-obvious bursts of magnetic recording along one edge, and the Speytec machine had a series of magnetic spots hidden under a printed arrow. These spots could be measured more accurately than they could be reproduced thus making each card individual. The security concern that gave rise to the need for anti-cloning features was the possibility of a legitimate user cloning their card and vastly overdrawing their account. When online banking became available the anti-cloning features were dropped. One wonders how much money, and grief, could have been saved if they had been continued.

Jack Donald CEng FIET, Chesterfield

Trolley history

I think Justin Pollard either misread or misunderstood his research on Frank Sprague ('The Eccentric Engineer', December 2007). Sprague invented the trolley pole in 1880 in order to facilitate current collection on the newly invented electric tram. This way the American 'street car' became the 'trolley'. The trolleybus - called the trolley-coach in America - did not appear until more than 20 years later and it was the 1920s, when road surfaces got better, before its short rise to popularity.

Thus Sprague's invention was in widespread use long before the trolleybuses which Mr Pollard refers to.

NC Friswell FIEE, Former editor, Tramway Review

Not professional enough

It would appear that the UK Environment Agency believes engineers are not professional. I have recently had to fill in forms to register as an account representative for my company under the emissions trading scheme and provide certified documents that are signed as a true copy by either a "doctor, bank manager, solicitor or chartered accountant". When asked, they refused the signature of a chartered engineer. Just another reason why engineers are not professional in the eyes of the money men.

Graham Park MIET, by email

When bees go free

Regarding the use of bees for the detection of substances ('The Honey Trap', December 2007), when they are released after one to five days in their holders, are they affected? Are they released near the hive or area they were originally found in? My concerns are that the bees may not be able to find food because they have been trained to stick out their tongues when they smell a particular substance, and they may not be able to reintegrate into their original hive.

Karun Dambiec MIET, Belconnen, Australia

High-tech takes off

Geoff Hatton's flying saucer platform ('Flights of Fancy', December 2007), is certainly an extremely innovative capability. I wish Geoff all the best with his endeavours, knowing full well how challenging it is in the UK to secure the required levels of funding and support for highly innovative small businesses in the engineering/high-technology sector, even though the global market opportunities provide high growth potential.

I was drawn to Geoff's comments regarding what he believes to be his closest competitor, the 'Damsel Fly' described as being built by Selex Sensors & Airborne Systems. This technology was actually conceived and patented by myself and the initial development carried out by VTOL Technologies Ltd under contract to Selex. The technology is now fully owned by Selex and although I would have loved to have had an opportunity to respond to Geoff's views that "although the platform has excellent avionics, it's not as stable as his vehicle", I am unfortunately no longer in a position to comment; now that technology ownership resides with Selex.

Ashley Bryant, Managing Director, VTOL Technologies

Lack of training hinders job selection

The mid-November 2007 issue of E&T Careers reports a comment by Imperial College senior admissions tutor Dr Stepan Lucyszyn that about half of Imperial engineering graduates go into city jobs, a quarter into academia and a quarter into industry ('Skills shortfall hits UK defence sector'). The story fails to mention that over half of these students are from overseas. Overseas students generally can't get an engineering job because most engineering employers don't give out work permits. Apart from this, Dr Lucyszyn is absolutely right about the engineering sector - companies should pay for the graduates. I'm not just saying increase salaries to more attractive levels - companies should be willing to mould and train people into the jobs. Last year I applied for several engineering jobs and was turned down for all but one. The reason was because I didn't have the experience or the degree focus in the field. I then turned to the finance sector and had several job offers for positions which I had no experience in. Now I command a salary which is the equivalent of a chartered engineer with four years' work experience. Somebody has to start recognising that not paying now is directly linked to the brain drain.

Will Wan, by email

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