Risk Calculation - Surge Protection Part 6

[@richardwash6678]

Nice one JW, you really take the time to explain calculations so it all makes sense. 👍

[@MalagasOnFire]

Nice to see practical videos with calculations for various scenarios applied to surge protection on UK regulation. Great Video . The local PT_PT Regulation available for Low voltage (RTIEBT) looks like that covers this type of protection in section 321.13 (lots of edit)

[@truckerallikatuk]

Hrm, that CRL calculation pretty much boils down to: Rural means install protection unless it's next door to a modern substation. The only way to get that bas level of 85 to anything like 1000+ is ifLP is a tiny fraction working out to 0.085 or smaller.

[@jwflame]

Yes. The calculation itself isn't of much use.

[@truckerallikatuk]

@@jwflame Indeed, only worth doing at all in urban areas.

[@SUPERCool786ABID786]

Your a Top Educator I have followed your videos very informative .. Doing my regs soon

[@shaunsparky5354]

Requirement for SPD 'Types' and relevant locations in electrical installations on the next video John? Limitations of 'theoretical' protection perhaps? Great work as ever, thanks again!

[@seanpassant3174]

Hi Shaun, Type 1 devices are "Lightning arrest devices" and only required if, there is structural lightning protection installed or the structure is fed via an overhead line. Type 2 devices are what the 18th edition is now highlighting, these would be at the origin of an LV distribution system (if no lightning protection) or in larger commercial / industrial applications you could see additional type 2's within the sub-distribution boards IF the equipment they feed is considered vital by the client. TYpe 3 devices should be as close as physically possible to sensitive terminal equipment, a fire alarm panel, a server etc. They are much smaller, some the size of a tic tac box, they can be placed in dado trunking, back boxes, or even in the terminal equipment itself. No SPD can offer protection for more than 10m (cable length) from it's location. If you have a combined type 2/3 device at the origin then no other device would be needed for terminal equipment less than 10m away. If you had something 15-20m away then you should consider additional protection. [e-mail] if you want to contact me for any further advice or have any other questions.

[@154electrician]

If we go into lockdown you should do a video every day ( try and include one on earthing generators ) 👍

[@DCMamvcivmEvony]

Yet another great video by JW.

[@EpicWinz]

I just put in surge protection as I go now - because it just makes sense too

[@edbouhl3100]

Particularly since we’re seeing storms both increasing in intensity and occurring more often in new places. Might not be much risk now but in 20 years?

[@acelectricalsecurity]

This is what frustrates me with the regulations, rather than giving a load of options as justification not to install it, just say surge protection has to be fitted, then there's no confusion 🙄

[@seanpassant3174]

This is what most other European countries did after IEC 60364 put SPD's in as standard across the board and CENELC accepted it as a harmonised European document. Only the UK chose to go with this clunky & awkward version where it's virtually impossible to not install the SPD but at the same time the document isn't actually saying that which gives the cowboys their get out of jail card.

[@ghita0407]

Very informative video, thanks

[@robswingler]

So what is the point in putting the single dwelling exemption in if it’s completely pointless?

[@AndyK.1]

robert swingler I guess you need to consider/make flats and bedsits to be except.

[@mattgayda2840]

Hotel room? That's the only single dwelling unit where someone wouldn't have lots of electronics....

[@rattlehead85]

Great video as always John... think most decent sparks are fitting SPDs now on cu changes as the cost doesn’t warrant the risk of not fitting one. 👍🏻👍🏻

[@JohnnyX50]

That black dot looks like its somewhere near Sleaford :) I live in Notts, I have a ton of extensions with surge protection built in and a computer UPS with it built in. Dont really get surges here, just the occasional momentary dimming of lights and rarely my UPS clicks in and beeps for a sudden under-voltage. I like how the map makes Notts look like lightning valley, I wish! I love lightning! Havent seen any in over a year lol

[@seanpassant3174]

The epicentre is slightly lower and further over, nearer Boston in Lincs, the data comes from ground monitoring stations and is a sample over many years. This epicentre is moving, it used to be even further down (north London basically) as our climate warms, we will see more lightning activity and since I started in the industry (28 years ago) the level of lightning activity in the UK has nearly doubled in some places.

[@stevesulley695]

l agree with your interpretation of this section of BS7671, but l have told twice now that l should recommend surge protection to my domestic customers but it is there decision whether you install it or not .l cannot see anywhere in BS7671 that allows this, could you please clarify this point regards s sulley

[@jwflame]

Nothing in BS7671 that covers that. For domestic installations it's do the calculation - is it required or not. If it is, then not installing it will not comply with BS7671. Even if not required, the cost for a typical domestic is so low that it's sensible to recommend it anyway. If someone absolutely insists they don't want it then advice from other organisations has been to get that in writing and have the customer sign it. My opinion is that if you have a customer who is complaining over an extra £50-£100 on a new consumer unit or rewire, then it's probably not the kind of customer anyone wants. The kind that wants everything else done on the ultra-cheap and will still complain about the price even if that's what they get.

[@stevesulley695]

thanks for reply ,l am with all way but there are some in the industry coming up with a different spin on how this sections regulations are applied regards s,sulley

[@DCMamvcivmEvony]

May be worth noting that the total distance of all of the L values without their multipliers added together is limited to 1km. Therefore it is often easier to default to 1km for Lpal and use its multiplier to give 2 1x2=2. In most applications of the calculation Lp will equal 2. I just auto-default to 2 as I do not know any of the lengths.

[@DCMamvcivmEvony]

Hadn't reached 18 mins yet. 😂

[@shaunsparky5354]

@@DCMamvcivmEvony OK, so you were just demonstrating a commentary observation. It's not a wasted comment, it is well worth noting the weighting of risk at each of the 4 stages (for what its worth) If the 1km value is applied to LPAL then it's 'risk' is attributed with x 2 to obtain the end value. Good point, well observed!

[@MartinE63]

The cynical would say that the DNO's have pulled a fast one and offloaded all the responsibility to the consumer when they should be fitting surge arresters at their distribution substations and especially at pole transformers. In urban areas fitting surge arresters within the consumer unit is fixing a problem that really doesn't or shouldn't ever exist.

[@Monkeh616]

And the realistic would admit that there are loads outside the control of DNOs which create transients which cannot be effectively clamped from 300m down the line..

[@shaunsparky5354]

Monkeh oooh, interesting. Can you evidence this please? I’d like to use it 👍

[@seanpassant3174]

@@shaunsparky5354 The evidence is in simple truths, no SPD can offer protection further than 10m away from itself in cable length so there would be no point in installing any SPD in subs or on poll Tx. Frequency oscillation alone can create 1,000's of volts. Switching surges, inductive loads, lightning strikes, pumps & motors kicking in repeatedly, fuses blowing, kids flicking lights on and off repeatedly, all of these can and do create transients and all are beyond the DNO's control. The over voltage protection has to be in the individual consumers property.

[@mattgayda2840]

See 17:30 for the answer, the tinfoil hat won't protect your electronics from surge generated by the neighbors or your own equipment.

[@123tinhat123]

If your house has been hit by lightning do you need surge protection or does lightning strike twice?

[@DCMamvcivmEvony]

Would be preferable but a type 2 at the supply isn't going to protect you from a direct strike.

[@seanpassant3174]

Is this a serious question? Yes lightning can & often does strike repeatedly, it's an old wives tale not science. For lightning arrest you need a type 1 device and it must be 12.5kA per phase minimum unless you can calculate and prove your level of current division.

[@nicholaspratt7934]

That risk assessment (>1000 -

[@clivedyson2053]

I thought so at first glance, but on checking protection is required of CRL < 1000. Both line length (LP) and the strike probability factor (Np) are in the denominator for CRL, so that as they increase (increasing the need for protection) CRL decreases. So the inequality is in the correct sense. It seems to me that using the inverse of the defined CRL would have been more intuitive, so that an increasing risk lead to a larger metric.

[@garyslatter9854]

Does it protect you from #ChineseBioWeapon

[@garyslatter9854]

/s missing

[@zyspan]

Great video

[@blancsteve4819]

Hi John. Some rotten git removed my RCD without my concent. It was just gone. No power interuption. Spooky. I should get it replaced but I am due to have a smart meter fitted. Maybe I will wait till then. Surry UK.

[@miguelferreiramoutajunior2475]

Boy ,At first I thought It was about Covid19.😆