surge/lightning protection

[zeidler]

how do you choose suitable surge diverter/arrester in au to protect single phase residential from surge/ lightning. ie ka rating ? 20ka/40/ka, ph to e

 

[buzzlightyear]

https://www.google.com/url?sa=t&sou...Vaw0Zf8-C4IhgIYwpppkspESW&cshid=1604117459972

 

[telectrix]

that's about as useful as a wet fart in a thunderstorm. what is "ground flash density" FFS.

 

[Mike Johnson]

how do you choose suitable surge diverter/arrester in au to protect single phase residential from surge/ lightning. ie ka rating ? 20ka/40/ka, ph to e

What is the earthing system of your electrical installation? is it from your electricity supplier or do you have an earth rod?

 

[pc1966]

The biggest difference is between "Type 1" SPD that are rated for a direct hit (10us/350us pulse shape) and "Type 2" that are rated for induced surge (8us/20us pulse shape). While you will see similar peak currents mentioned in the 10kA to 40kA region, the order of magnitude difference in pulse duration means there is a massive difference in energy handling.

Generally if the building has lightning protection conductors you must use Type 1 (or combined Type 1+2), but also if you are at the end of a long overhead line and/or in a high region of activity you might be best to go for the high energy handling of them as well as they will last longer at medium surge energies.

Otherwise you use Type 2 as they are enough for nearby surges, and also at sub-boards that are 10m or more away from any main Type 1 incomer protection.

As for the different ratings, you get different degrees of lightning protection system rating (I, II, III and IV) that cover the probability of being hit, survivability, etc. Basically it comes down to risk management.

This PDF document covers more than you are likely to need to know:
https://www.erico.com/catalog/literature/E907W-WWEN.pdf

 

[zeidler]

What is the earthing system of your electrical installation? is it from your electricity supplier or do you have an earth rod?

earth stake

 

[Rockingit]

that's about as useful as a wet fart in a thunderstorm. what is "ground flash density" FFS.

No idea mate, but it's page 102 ?

 

[Mike Johnson]

Oh I don't know a wet behind in a Thunderstorm may be quite conducive and useful to protect the building. ?

 

[Rockingit]

True thing.....

I won't mention the place by name but there's a BIG 'rooftop' swanky bar and eating venue in central London that I did a couple of years ago. I was off site for a couple of days, came back..... to discover that someone who knows more about 'art' than physics had decided to clad the main bits of all of this in 3mm pure copper sheet. The look on the site agents face when I asked who'd done the lightning strike risk assesment was priceless ?

 

[Robson689]

No idea mate, but it's page 102 ?

https://shop.bsigroup.com/ProductDetail?pid=000000000030312912

Here is where you can purchase the flash density map

 

[westward10]

It is a myth that a metal roof is more likely to attract a lightning strike.

 

[Mike Johnson]

The safest place to stand in a thunderstorm is in the middle of a field with a 1 iron above your head, because not even God can't hit a one iron. (Lee Trevino)

 

[mattg4321]

So said Lee Trevino anyway. I’ve always kept a 1iron in my bag!

 

[Mike Johnson]

So have I, but the bag it's in is in the shed and never goes to the course.

Previous post attributed.

 

[Rockingit]

It is a myth that a metal roof is more likely to attract a lightning strike.

Not sure I agree with you on that.... a metal roof in isolation, absolutely - agree. But a metal structure which is by necessity fully bonded to earth......

 

[telectrix]

a keen golfer was playing a round of golf with the local priest. , on the first tee, he missed the ball completely and swore "Bollox missed the -------". the priest tutted but said nothing.
2 hole later, same again "Bolloxmissed the -------.". Cutting a long story short, after the 5th occasion, the priest had had enough and said " if you swear like that again, God will strike you down".
on the 9th, similar missed hit and again " Bollox, missed the -------"

Suddenly, there's the sound of thunder in the sky and a bolt of lightning shoots down and stikes the priest stone dead.

a deep voice sounds from above.....


" Bollox, missed the -------"