Lightning Arrestor installation 3

[Histor]

Hi,

As shown in the image above, We have a Lightning air terminal installed on top of the structural platform. from Lightning Air terminal the 150kA LGR cable is going to connect with nearest Earth Bar. The Earth bar will be connected to the underground Rebar Grid.

My Concern is using the PVC insulated cable is not a general practice in my experience. I always have seen tapes. Could anyone please tell me using PVC insulated copper cable is acceptable ?
Any Standards? If PVC insulated cable can be used, how can I size this cable or what size cable is more suitable?

We are also not using test link, is this a problem?

please help me. Thanks.

 

[dik]

I'm not a sparky, but I've not seen insulated cable use with lightning protection. It's always been 'bare' braided copper cable.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[3DDave]

It won't be PVC coated after the first lightning strike.

 

[che12345]

Dear Mr. Histor (Electrical)(OP)
" #1. ......My Concern is using the PVC insulated cable is not a general practice in my experience. I always have seen tapes. Could anyone please tell me using PVC insulated copper cable is acceptable ?"
1. As per NEC which is the Law in the US states : " .... ground electrode conductors shall be solid or stranded, insulated, covered, or bare ....".

"#2. .... Any Standards? If PVC insulated cable can be used, how can I size this cable or what size cable is more suitable?...".
2. See IEC or NEC depending on the local regulation.
2.1. BTW: The usual PVC is rated up to 70 [sup]o[/sup]C. The lightning impulse usually is much lower than 200kA for a duration of < micro-second. The heat generated ( impulse i[sup]2[/sup] x t ) is very much lower than the (rms i[sup]2[/sup] x t). This is the main reason why we don't see the conductor being fused up.

" #3....We are also not using test link, is this a problem? "
3. Test link is NOT a must. It is useful for isolating the other parts when testing the earthing resistance.
Che Kuan Yau (Singapore)

 

[prc]

The LA earthing lead can be copper or steel strip.

 

[dik]

Wouldn't the insulation cause the wire temperature to increase a tad by not allowing the heated cable disperse the heat to the atomosphere?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[che12345]

Dear Mr. Histor (Electrical)
"....My Concern is using the PVC insulated cable is not a general practice in my experience..."
1. @ 3DDave (Aerospace)24 Dec 22 04:38
"...It won't be PVC coated after the first lightning strike."
Please advise at what lightning (impulse 100kA----200kA and the duration ) that you had based on that the 120mm[sup]2[/sup] copper conductor would be (heated up to) that the [PVC insulation would be damaged/destroyed]? .
2. @ dik (Structural)24 Dec 22 04:00
".... I've not seen insulated cable use with lightning protection. It's always been 'bare' braided copper cable."
Please advise which standard (IEC or ANSI) and [what is the reason] that it is always 'dare' braided?
Che Kuan Yau (Singapore)

 

[dik]

I'm not a sparky (electrical guy), and I don't know what standards have to be met... I'm mostly structural I've only seen uninsulated cables (bare) used for lightning protection.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[che12345]

Dear Mr. Histor (Electrical)
"....My Concern is using the PVC insulated cable is not a general practice in my experience..."
@ dik (Structural)26 Dec 22 02:14
"... Wouldn't the insulation cause the wire temperature to increase a tad by not allowing the heated cable disperse the heat to the atomosphere?..."
Per IEC, ANSI, NEMA standards, the (lightning impulse current peck) may (but very unlikely) to exceed/reach 200kA. The (duration) is (always) [in micro-second]. The heat generated that causes the temperature-rise on the conductor is always taken as isometric i.e. taken as without any heat lose/exchange with the surrounding cooling media or any thermal-conducting material. This assumption is valid, in view of the extremely short duration; in the range of micro-second.
Che Kuan Yau (Singapore)

 

[dik]

Is there a purpose of having insulation, other than maybe a corrosive environment?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[che12345]

Dear Mr. Histor (Electrical)
@ dik (Structural)26 Dec 22 02:14
"#1. ... Wouldn't the insulation cause the wire temperature to increase a tad by not allowing the heated cable disperse the heat to the atomosphere?..."
Corrigendum
I refer to my earlier post dated 26 Dec 22 10:24 and noticed a typo error:
"....The heat generated that causes the temperature-rise on the conductor is always taken as isometric i.e. taken as without any heat lose/exchange with the surrounding cooling media or any thermal-conducting material."
The word isometric is a typo error. It should be adiabatic = no heat transfer.... My sincerer apology.

"...#2. Is there a purpose of having insulation, other than maybe a corrosive environment?.."[/color].
Mainly for prevention of (corrosive environment) in the [air and in the earth/soil], for buried conductor.
Che Kuan Yau (Singapore)

 

[Histor]

Dear Mr. Che Kuan Yau,
May I know what IEC/NEMA standard covers the lightning current and conductor to be used?

Is there Singapore Standard that covers the same?

 

[che12345]

Dear Mr. Histor (Electrical)(OP)26 Dec 22 23:30
"#1. ....May I know what IEC/NEMA standard covers the lightning current and conductor to be used?"
See (a) IEC: [ 62305-1,2,3 & 4 ]. [62541-1,2,3 & 4] etc....
(b) NFPA 780, etc .....
(c) UL 96A etc....

"#2. ....Is there Singapore Standard that covers the same? "
See SS 556 Part 4 (=IEC 62305-4) etc ....
Che Kuan Yau (Singapore)

 

[Histor]

Dear Mr. Che Kuan Yau,
Thanks for the standards.