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 Post subject: PPE in Europe 220 or 230 V single phase
PostPosted: Wed Nov 14, 2018 8:14 am 

Joined: Tue Nov 04, 2014 5:53 am
Posts: 15
Was curious - what PPE is required in Europe when working on 230 Volt (220V) single phase?

Trying to determine appropriate PPE for 240 or 208V single phase equipment in USA fed from high KVA systems (typically greater than 500 kVA transformer source).

My thought is to calculate as three phase and label as such even for single phase loads.

Does IEC Standard 60900 Live working address?

Thanks in advance for everyone's thoughts.


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 Post subject: Re: PPE in Europe 220 or 230 V single phase
PostPosted: Wed Nov 14, 2018 7:46 pm 
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IEC 60900 is still somewhat of a work in progress. I would say that they are where NFPA 70E was at in the 1990's...give it some time. Right now the fundamental difference is that the European approach has more or less been to focus on preventing arcs in the first place or containing arc flash (arc resistant gear) so PPE is less of a focus in the IEC standards and I would almost go so far as to say ignored in terms of arc flash although it has substantially the same standard when it comes to shock protection. The major differences are in using a more advanced model for human body resistance compared to a relatively fixed resistance (1 kilo-ohm) which is prevalent in North American standards as well as using a more complex curve in terms of time vs. current compared to the relatively simple Dalziel-style model. This is helpful in designing grounded systems but not all that useful for PPE determination since PPE considerations are for phase-to-phase shock hazards as well as phase-to-ground.

NESC (IEEE C2) and IEEE 516 (live working on overhead lines) probably cover more what you are looking for. IEEE 516 is intended for overhead line work but it is so comprehensive that it provides the foundation for pretty much every other standard when it comes to shock protection including other IEEE standards, NFPA 70E, and OSHA. IEC is still behind where IEEE and NFPA are at in a lot of respects. There have been occasionally posts on this forum about their progress which so far has been slow. IEEE C2 (NESC) covers work procedures as well as construction methods for utilities although with regards to arc flash OSHA is still somewhat on the fence in terms of accepting NESC vs. their own procedures in OSHA 1910.269 due to some differences in interpretation when it comes to arc flash. Unlike NFPA where we have a distinct line between equipment installation (NFPA 70), maintenance (NFPA 70B), and work procedures (NFPA 70E), NESC contains both equipment and work procedures in a single standard.

When you say 220 or 230 are you referring to 230/220 V (which are basically one and the same), or 230 kV?

If the former then there has been testing done on single phase vs. 3 phase arcs and frankly there isn't a huge difference between them in terms of the result (incident energy) so IEEE 1584 both in the current (2002) edition and the upcoming draft edition state to just use single phase results for conservative purposes for calculating incident energy. NFPA 70E has extensive procedures as well as PPE recommendations for those voltages.

Above 10 kV (if it's the latter) then although IEEE 1584-2002 includes the Lee model, that one is really awful in terms of modelling particularly at medium voltages and the errors get even worse as voltage increases. The big problem is that for the most part arc flash is strongly influenced by current while there is only a slight influence by voltage where the Lee theoretical model by nature gives them equal weighting so as the voltage increases, the model error increases dramatically. The best modelling you can do is with ArcPro which is a theoretical model for single phase vertical arcs and is especially suited to the range above 15 kV where the IEEE 1584 model is not really suited. You are still going to run into an arc gap (phase spacing) problem though with ArcPro and I don't have any good answers for that. Therein lies the problem...the phase spacing is so wide at 230 kV that orientation of both the arc and the worker have a great deal to do with the result but unfortunately no testing has gone on at those voltages to do anything resembling justice. So ArcPro remains your best (theoretical) bet but it's not going to be the answer you are looking for if you are looking for 230 kV.


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 Post subject: Re: PPE in Europe 220 or 230 V single phase
PostPosted: Fri Nov 16, 2018 12:51 pm 

Joined: Tue Nov 04, 2014 5:53 am
Posts: 15
Thank you for the thoughtful reply! I am referring to 220 volt (230 volt) low voltage single phase circuits - derived from say a 380/220V three phase 4 wire system.

In that regard did you mean to say three phase results below:

Quote:
If the former then there has been testing done on single phase vs. 3 phase arcs and frankly there isn't a huge difference between them in terms of the result (incident energy) so IEEE 1584 both in the current (2002) edition and the upcoming draft edition state to just use single phase results for conservative purposes for calculating incident energy.


Thanks again

Bill


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 Post subject: Re: PPE in Europe 220 or 230 V single phase
PostPosted: Sat Nov 17, 2018 4:03 pm 
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Yes, I meant 3 phase. I can't remember precisely but I believe Lang was the one that was testing how much if any effect phase barriers had so along the way he basically ended up doing some comparative testing for single phase arcs. The incident energy was less but not drastically so. To my knowledge this is the best comparative data out there.

The problem with arcing below around 250-300 VAC in terms of modelling is that frequently the arcs will not be self sustaining or if they are self-sustaining they are very weak arcs. IEEE 1584 (current and upcoming new editions) recognizes this by setting a very low threshold below which the incident energy is below 1.2 cal/cm2, but your scenario is well above that threshold. IEEE C2 (NESC) used empirical testing results and gives a table in Article 410 which essentially states that up to 250 VAC under any conditions arcs will not exceed 4 cal/cm2. The underlying testing was done by EPRI. The testing is publicly available for free and the worst case arc they were able to create was 3.2 cal/cm2. That's not to say that serious injuries or fatalities cannot occur. There was a particularly extreme case in 2009 in Georgia which left 2 men hospitalized and one of them subsequently died from exposure to a temporary construction panel that arced at 240 VAC. However their PPE consisted of tank tops, shorts, and flip flops so it may not have been up to the task.


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