Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 10 replies
  • Subscribers 32 subscribers
  • Views 891 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Arc Flash: ‘It Will Never Happen to Me’ - One of the UK’s Most Overlooked Safety Risks

John Beirne

The HSE states that around 1,000 workplace electrical incidents are reported to them each year including circa 25 fatalities a year.  However, it is also believed that arc flash incidents are far higher than officially reported.



I would like to think that you would all agree that the above mentioned amount of incidents is not acceptable.  Therefore, how can we reduce the risk of arc flash?  I am working with IET Safety Panel reviewing the ‘Arc Flash Protection Fact Sheet’ and I need your help to understand why we have so many incidents and fatalities and investigate barriers to reduce such incidents and fatalities.



Some of my thoughts are:



PPE Regulations (EU) 2016/425.



Does PPE Regulations (EU) 2016/425 satisfy your requirements?  (yes we need to drop the EU).



Do they need amending and if so where and why?



Reporting.



Is there a requirement to improve the incident reporting format, to provide greater clarity and understanding of how such incidents occur, thus allowing us to look at the human factor elements?



Training.



Is there a requirement to improve training and or standards with respect to arc flash?



There is a various amount of literature about control measures and how to mitigate arc flash, which can be confusing.  Is there a generic risk assessment for Switching (Either LV or HV) that identifies arc flash?



Is the arc flash risk assessment understandable and easy to follow?



Personal Experience.



You may have witnessed arc flash and wish to inform us why you believed it occurred.



Thank you for reading this forum and trying to promote a safer working environment for your fellow electrical engineers.  I look forward to your constructive replies.



Kind regards,



John


  • 0
    Just to clarify: is that 1000 / 25 specifically arc flash incidents, or electrical incidents generally?
  • 0
    Are you not including HV and high current distributer incidents in these figures? They're rather beyond the scope of BS7671.
  • Former Community Member
    0 Former Community Member
    These are the figures I found. The 15004 figure includes short circuits and overloads, rise in voltage above statutory limits, collapse of structures, unauthorised access etc. 

    Regards

    BOD

    https://www.hse.gov.uk/statistics/tables/index.htm#esqcr
    Safety-related electrical incidents reported to HSE in Great Britain 2015/16 - 2019/20p

     

     

     

     

     

     

    Source: Electricity Safety, Quality and Continuity Regulations (ESQCR)

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    Year

     

    Incident type (a)

    2015/16

    2016/17

    2017/18

    2018/19r

    2019/20p

     

    Fatal injuries

    6

    7

    5

    4

    4

     

    Serious (non-fatal) injuries

    434

    351

    315

    252

    231

     

    Other Events (b) 

    14,921

    14,588

    13,478

    14,993

    15,004

     


     

    Table reference

    Explanation

    Incident type' (a)

    An incident can cause more than one fatality or injury. The total number of injuries are presented in the table

    Other events' (b)

    Examples of reportable 'other events' include: any short circuit or overload; death of domestic pets or livestock that would indicate the existence of potential current flow sufficient to kill a person; public access to exposed live conductors or any contact with live conductors by persons, plant or equipment used by members of the public; events where the failure of a protective multiple earthing (PME) neutral causes a rise in voltage above statutory limits; reverse polarity on customer’s premises or street furniture where the error is found to be located in connections under the control of a duty holder; partial or complete collapse of structures including buildings and wind turbines; unauthorised access to any high voltage equipment including substations; theft or attempted theft of operational apparatus e.g. the removal of earth conductor from a pole or in a ground-mounted type substation

  • 0
    Hi John,

    I’m not clear on how many of the 1000/25 incidents involve arc-flash, what is the proportion?  And why is it believed to be higher than that figure?  Also, are the system voltages known for these incidents so that the data can be better understood?  There may be specific sectors of work where most of the incidents occur – I suspect that not many occur in your ‘everyday’ commercial low voltage network.

    Are these arc flash incidents due to switching or some other mode, such as those which might occur while working on live switchgear? 

    Regards arc-flash incidents due to switching, perhaps the root issue might be that switchgear with internal arc containment had not been installed.  In that case it reasonably ought to be asked, why not?

    Where arc containment could not be reasonably achieved at the switching device, it would be useful to know if the those proportion of incidents, occur as result of the existing standards and guidance being ignored.  For example, had a reasonable assessment of risk been carried out per IEC 61641? Or were the risk assessment / PPE requirements ignored?

    “How can we reduce the risk of arc flash?”

    If the equipment and guidance are already available to manage the risk, perhaps effort is required to be expended in training and awareness, and understanding where to focus that effort.  I suspect that the target audience would be specific segments of the facilities maintenance market, but I’m open to being corrected.

    As an aside, I have noticed growing emphasis on arc flash in various places in the industry but I’m not sure what has stimulated it – any ideas?  Has there been a recent rise in arc flash incidents?

  • 0
    I know we are probably talking about AC arc flash here, but as more DC power is being used, and in particular with large battery storage systems, we may well see more incidents. It's certainly not unknown for those installing UPS, and not following manufacturer's instructions on the sequence of installation of batteries, to have had nasty burns from arc flash events.


    For this reason, an arc flash assessment and risk assessment process was included in the recently published second edition of the IET Code of Practice for Electrical Energy Storage Systems, to help designers of discrete component battery systems (custom-designed, rather than purchased as a pre-assessed product) address the issue as far as practicable in design, and also select suitable working practices and PPE for installation, commissioning, maintenance and decommissioning.
  • 0
    Dutch,


    Thank you for your reply.  I have some further investigation to continue with.  This subject is very interesting and the thought of making it a safer environment for our electricians to work in is definitely high on my agenda.  You may have gathered that I am not electrically biased: I am an aviation engineer.  But if I can ask those questions to make sure we have it right, which is good.  Have you read the Arc Flash Fact File on the IET Site and do you think it is useful?

    https://www.theiet.org/impact-society/factfiles/engineering-safety-factfiles/briefing-arc-flash/


    Once again thank you for the 'best reply'.


    Kind regards,


    John
  • 0
    That leaflet would be more use to the average sparks if instead of just saying wear cotton undies (*) for irradiance energies up to 4 cal/cm2 or whatever,   it added a 'typical case' column that related that in some way to a representative  situation  for each class - it is not easy without a lot of extra knowledge and calculation to say if that equates to working on a circuit protected by a 13A fuse, or working on a bus bar protected by a 100A mains fuse, or climbing a pylon...


    Calories per square cm probably sound to most folk like a measure of the diet ratings for sandwich fillers,  now some of us can do the hard sums  but to say ' equivalent to working 100mm from conductors protected by an XYZ fuse  at PQR voltage' would be far more informative and avoid serious decimal point errors- or better still add a few worked examples. as appendices.

    regards

    Mike


    (& perhaps add advice to bring a spare pair of said cotton undies if you have a  nervous stomach. I know at least one high power RF designer who always vanishes to the gents for 5mins just before 1st switch on of any new system ?)


  • 0
    Serious arc flash accidents are rare in UK.

    Some of the greatest risks are IME, when electricians with experience only of domestic and similar size work, are left without any extra training or PPE to work on high capacity switchgear.


    "Must be OK he is fully qualified" and the infamous "company policy prohibits live working, so no PPE is needed beyond the polyester uniform"


    I have witnessed a significant arc flash incident in a large department store. A young and not very experienced electrician fiddled with a defective busbar system, that was fed from an adjacent transformer via 400 amp fuses. I know not exactly what went wrong, but there was a substantial flashover which operated all three fuses. He was burnt badly enough to require a week in hospital. No PPE was worn beyond the normal polyester uniform.

    I was aware of an incident at an office block where I was the engineer, but was on holiday at the time. On my return from holiday I was due to replace the batteries in a large UPS. I had done such work before and felt well able to do it. The new batteries were delivered earlier than expected, and a keen young manager instructed that the holiday relief should fit the batteries. This ended in a very substantial blow up with injuries and destruction of property.

    I suspect that the two battery strings were connected incorrectly.

    The keen young manager was sacked and the two electricians resigned. 


    On the old forum is a thread in which I suffered an arc flash incident but escaped injury due to wearing suitable PPE.

    link to old forum.
  • 0
    And those examples you give are the very sort where more specific advice than that in the leaflet linked above would help such unskilled folk and perhaps avoid such poor  decisions.


    I suspect that none of the folk you are talking about would have looked at the job and come up with a figure in calories per square cm.

    If the IET wishes to offer authoritative guidance it needs to be in a  form digestible to those who need it.


    I do not consider this guidance to be very digestible either, but at least it gets the mathematically skilled reader  from  PSSC and distance to the bit of body to be protected, to something like an energy density, and that could be linked to a PPE spec.


    However just including a few ready reckoner graphs of closest distance vs  PSSC for various classes of PPE would make it easy for the casual reader -

    ooh my hands are 50mm from this 10kA PSSC supply,  - look at the curve I need XX protection, my face and chest is 30cm, that needs YY etc.

    Yes there are approximations and assumptions by the shed load, but at least it avoids the uninformed either insisting full body armour for changing a light bulb,  or permitting tee shirts and sandals for working on the company cut out - both of which I have witnessed.



    Mike.


  • 0
    I would support a lot of what is said here - there's a general ignorance of arc flash in LV systems, the forms of our switchgear and majority of working practices should render an arc flash incidence a remote possibility these days, and perhaps some guidance could be given in terms of prospective fault current vs fault time and working distance, as Mike has said.


    Battery storage systems might well be the game changer here, although good system design can help reduce the risks.


    I also agree that cal/cm2 is not really the sorts of SI unit that we are used to in the UK - but the issue is that conversion to Joules is not linear with temperature, and most arc flash PPE is manufactured for those units - so that's another learning curve to get over.


Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines