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BS 7909 and Temporary Electrical Systems, what next?


It has been a VERY busy year, one in which I have found myself getting involved in all sorts of things that are keeping me out of the office!

On the plus side, I have lost a little weight and have enjoyed getting 'hands on' with various projects big and small. I have met some very good people and had some very interesting discussions. I have seen some really good installations, which is encouraging.

On the minus side I have worked some crazy hours, not had time to keep up with media stuff and I have missed some of the big rugby games (watching, not playing!).

Worst of all, I have seen some appalling installations and practices, in both fixed and temporary installations.

I will leave fixed installations for another day, and concentrate here on temporary electrical systems. These should comply with the relevant parts of BS 7671:2018 as well as BS 7909:2011, and also afford compliance with various Statutory Regulations such as EaWR 1989 and PUWER 1998. In short they should be fit for purpose and safe!

The problem with ALL electrical systems is that it does not take a lot of knowledge to get them to work. Connect a conductor somehow to a terminal at the supply, run it to a load, run another conductor back to a different terminal and hey presto! It will normally work.

A generator that was part of a system I checked this year had only one 125A three-phase BS EN 60309-2 outlet on it. The customer wanted a 63A and a 32A three-phase outlet as well, so the generator company hard wired two additional leads direct into the live side of the output. When the generator was running, the sockets were live, what more could we possibly want! The fact that there was no overcurrent protection at all to protect the 6mm and the 16mm H07RN-F cables running out to supply the sub-distribution did not seem to matter to them. In addition when testing the supply on the 32A for earth loop impedance, I recorded values of up to 12 Ohms, over a one metre length of SY cable, so I suspected that the earth connection for this was probably a rusty bolt somewhere inside?

An earth fault on a piece of equipment could have been fatal, but if no fault occured, (and we had not spotted it), then this arrangement could have been considered successful and acceptable by the generator guy, and used again.

At another event a marquee company wired the lighting into a large marquee they had erected. Using rented fittings, with 1200mm LED strips, they plugged 36 units end to end (each fitting had a length of blue arctic with a 16A BS EN 60309-2 coupler and socket arrangement) to make a chain that ended up 260m long. It still worked!

When tested, quite apart from two polarity faults, I also found that the fault current was insufficient to achieve disconnection times at the centre point, let alone the end! In fact the disconnection time when assessed would have been over three and a half minutes, whereas the cable would have reached its maximum temperature within six seconds! After that, it would probably have caught fire, along with the marquee and the 500 people using it. When challenged the marquee supervisor said to me "well, we are not electricians, so we wouldn't know about these things" , how true!

It got me thinking about the training and education side of things again. We have had BS 7909 in its current form since 2011 and we have been delivering training on BS7909 for a number of years.

In fact Ascot College of Electrical Studies was the first training provider (in the world) to have our BS 7909 training programme accredited by City and Guilds. We started delivering the Accredited version in March 2014, and have had over 300 successful candidates through our BS 7909 - B course. We also have an accredited BS7909 Management course and since 2017 have added the C- course to the accredited programme.

We are not the only provider, James Eade has also been delivering training on BS 7909 for a number of years, and recently with the backing of BECTU and now NAPIT, this course has also been approved as a City and Guilds Accredited programme. Well done guys, we welcome this development, as there are more than enough candidates needing the training, and although we do cover the whole country, and abroad, it is healthy to have some competition. We may have different styles but I am sure we have the same goal, to keep everyone safe.

So is the training that we are both providing working? Why are we still getting so much poor installation work? What are we missing, how can we improve?

One of the many issues with temporary electrical systems is that the groups of people installing them are as diverse as the systems themselves. Temporary systems are like an electrical LEGO kit, the equipment simply plugs together and anyone can do it. I have often said that if you put the equipment in a school playing field with a group of nine year olds, they would work out how it fits and put a system together, what is more, it would work! But would it be safe and fit for purpose?

We have provided a lot of training for Film and TV crew, who were required by BBC, ITV, SKY etc to have BS7909 training, so that helped motivate them to come along. We have also been the training provider for a number of major players in the temporary power industry, but there are so many others that need the information.

Sound, lighting, effects, catering, power, heating, ventilation, film, TV, radio, theatre, weddings, parties, festivals, and so on and so on - all have different requirements and load characteristics, but all need safe electrical systems. Large sections of some of these industries are not coming forward for electrical training, due to cost, time, fear, whatever!

We are open to change at Ascot College, and as such are reviewing our BS 7909 programmes constantly. We are looking to further develop the suite of courses that we provide to include more relevant information for various different users, and also to provide the opportunity for Continual Professional Development, CPD. One issue we have been made aware of is that once candidates have completed their training they would welcome ongoing support in the form of workshops, on-line resources and exercises.

What we would like is some constructive feedback and suggestions from the hugely diverse array of people out there that are installing systems, large or small. What do you want to know about, what confuses you, what are you not sure of?

We also feel that now we have a new updated wiring regulations, is it not time to update BS 7909?

Some ideas we have had for amendments or additions to BS 7909;

i). More clarity on generator reference earthing

ii). Changes to the test results sheet to include calculated values

iii). Introduction of Medium scale events, perhaps over 6kVA but not exceeding 44kVA

iv). More guidance on RCD's and discrimination for final and distribution circuits.

v). More clarity on bonding requirements.

vi). Use of SPD's and/or AFDD's in temporary systems.

vii) Guidance on acceptable methods of connection/splitters etc.

viii) More clarity on cables underground (minimum methods, depth, type of cable etc)

ix) For indoor events, guidance on suspended cables and cables in evacuation routes.

Don't sit back and let others decide what you need or want, changes are happening in the electrical industry, its a good time to get involved and have your say.

Let us make changes for the better!

Stay safe.


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