I'll bite for you  :-)

If the exam question is "Is there a need for arc flash surveys in the UK ?"  Possibly, but I suspect in  a lot of cases not a full survey.

Do realise that the legal base around the UK wiring regs (BS7671 mainly) is not like the USA, and the regs themselves are a standard, but are not a legal requirement generally, although in most cases you need a good reason to go very far off the beaten track, you are allowed to if you can show an equivalent or better standard of safety to that which a regs compliant installation would provide in that particular case. Also a lot of our distribution networks, that is the stuff at higher powers that is mostly under the street, up on poles or in basements, is excluded from coverage under BS7671 at all.

As such for a new measure to be adopted in a permissive system, a better level of explanation is required than where a workforce is used to the imposition of mandates and permits. There is probably a need to educate about the situations where flash burns can be an issue, and corollary, those situations where it cannot. To that end, as part of that  there is a need to translate to and from some things we actually do measure or deduce as  a matter of course when designing a system - I'm thinking that we already look at /know   PSSC (in kA) and disconnection times (ms) and let though energy (joules per ohm)  and all that is needed is a means to put an upper bound on the energy density in joules per m² at the boundary of the arc sphere, or perhaps to deuce the radius of the third degree burn arc sphere where that density falls below 5J/cm²

The other problem we have is a lot of 50-100 year old kit in our higher power distribution networks that we know does not really meet the standards of today anyway, but no-one is going to change it until it fails. It would be good to know in which parts of the systems the current accidents are occurring. I'd not be too surprised if it was this 'legacy' kit that would be largely unaffected by a change of rules.

Mike.

Many thank for the bite... .  Good feedback. 

In the main LV distribution rooms we have charts for all settable protection, which are outputs from grading surveys. This is there to justify the settings and assist if a switch is changed.

We could as a starter make it clear what the actual KA is on a subsequent table for all switches, in essence the closer to the origin the higher the KA .  Then a KA to Cal value/incident energy level table,  Earth loop Zs tests are done at the furthest points to show worst case for disconnection however, this could also be done locally at the outgoing switches to demonstrate a "bolted fault" energy level.

Food for thought.

Cheers.

Steve

we do (usually)  measure PSSC - 'prospective short Circuit current'  - the higher of a phase to neutral or phase to ground or phase to phase case as part of commissioning.
(Though often we actually test P-E and P-N, and double whichever reads larger and assume P-P will never be much more than that )
We could write PSSC and I2t (joules per ohm) on the wall next to each box I suppose. Generally the table of test results  goes with the design documentation and in some establishments it seems that can never be found in a hurry.

Supplies at LV (230 single or 400 3 phase) are rarely more than 16kA at the origin, and fall to sub kA for domestic and small commercial buildings like shops.
Mike

we do (usually)  measure PSSC - 'prospective short Circuit current'  - the higher of a phase to neutral or phase to ground or phase to phase case as part of commissioning.
(Though often we actually test P-E and P-N, and double whichever reads larger and assume P-P will never be much more than that )
We could write PSSC and I2t (joules per ohm) on the wall next to each box I suppose. Generally the table of test results  goes with the design documentation and in some establishments it seems that can never be found in a hurry.

Supplies at LV (230 single or 400 3 phase) are rarely more than 16kA at the origin, and fall to sub kA for domestic and small commercial buildings like shops.
Mike

Many thanks for this Mike good feedback...Cheers!