Lightning protection for Shelter

[Histor]

Hi All, we have 2 numbers of Low voltage MCC kept inside a shelter in outdoor tankfarm area.
The Dimension of the shelter is 5m length, 3m Width and 3m height. Does this small Shelter requires lightning protection as per IEC standard?
There are Tanks and high structures are there in this tank farm area.

 

[che12345]

'...we have 2 numbers of Low voltage MCC kept inside a shelter in outdoor tankfarm area. The Dimension ..... Does this small Shelter requires lightning protection as per IEC standard? There are Tanks and high structures are there in this tank farm area'.
I have the following opinion for your consideration.
1. As there are high structure there in the tank farm, i.e. at close proximity, the high structure lightning protection should cover it. The risk is minima. NO additional lightning protection is required.
2. Attention: The conductive shelter surfaces, the MCC and any other conductive pipes MUST be properly BONDED and EARTHED.
Che Kuan Yau (Singapore)

 

[Histor]

Thanks Mr. Che Kuan.
If I install a 1m tall lightning rod on a 3m high shelter, Does it require a wind load calculation as per IEC?

 

[che12345]

@ Mr Histor (Electrical)(OP)23 Aug 24 01:43
'..If I install a 1m tall lightning rod on a 3m high shelter, Does it require a wind load calculation as per IEC?'
1. I must apologize that my earlier post may had misled you. The opinion was based the very simplistic general lightning installations. Your question on "wind load calculation" per IEC is some thing I have NO knowledge at all.
2. On the other hand, I was unable to locate in IEC, NFPA, UL , LPI any information on the subject you had raised.
3. BTW: " a 1m tall lightning rod on a 3m high shelter" is of extremely low height, in term of the 45m rolling sphere.
4. I would presume that NO wind speed would be strong enough to cause any damage to the (listed/labeled/tested) 1m strike terminal. If you would like to be on the safe side, lower from 1m to say 250mm would be fine. The total height would be 3.25m. I don't think anyone is going to make an issue on "wind load calculation", at this (low) height.
Che Kuan Yau (Singapore)

 

[Histor]

There are highest structure which are 6m tanks, 9m street light poles are nearby. But I don't see any lightning protection for them. So If I roll a spere they would roll only on street light pole and tanks only. Since there are no lightning for those structure it can not fully protect my shelter. Is my opinion makes sense?

 

[che12345]

Histor (Electrical)(OP)23 Aug 24 05:14
'There are highest structure which are 6m tanks, 9m street light poles are nearby. But I don't see any lightning protection for them...Since there are no lightning for those structure it can not fully protect my shelter. Is my opinion makes sense?'
1. I am convinced that you are very prudent, have very good experience/knowledge and have done your research thoroughly on the matter raised.
1.1 BTW: Are you facing difficulties with the insurance Co. or inspector ? You may have to out source it to UL for their expert service.
2. Those nearby high structure 6m tanks (if metallic), 9m street metallic light poles if they are Earthed to say <5 Ohm, would act as strike terminals, irrespective whether any visible lightning protection installed with them.
3. Based on 2. above, I am of the opinion that the 3m shelter is Fully lightning protected. Also 3m + 1m terminal need NO "Wind load calculation".
4. Attention: The shelter conductive surfaces, MCC and any extraneous conductive surfaces MUST be BONDED and EARTHED to say <5 Ohm. Note: It is usual for lightning protection, the earthing resistance is higher, say <10 Ohm.
Che Kuan Yau (Singapore)

 

[Histor]

Thank you so much for the detailed explanations.

 

[waross]

If the wind blows directly and evenly on the largest side of the structure, the ratio of structure area to lightning rod area is about 600:1.
Are we concerned that persons or objects may be impaled by the rod in the event that the structure bacomes airborne and eventually descends Lightning Rod foremost?
Probably not.

To add to Mr Che's good advice.
While I still have not seen everything and am still surprised from time to time, if the street lights are mounted to concrete foundations, the anchor bolts set in the concrete tend to form a "Ufer Ground".
Add to that that in some countries local codes require an additional grounding electrode at each lamp standard.
This may be an approved plate electrode be placed in the bottom of the excavation before the concrete is poured or a driven rod electrode.
In many countries, Mr. Che's criterea will be met by typical installations.
eg:

9m street metallic light poles if they are Earthed to say <5 Ohm,

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Ohm's law
Not just a good idea;
It's the LAW!