What is the best way to install lightning protection on roof top HVAC equipment

[mshields]

How should one specify lightning protection on roof top equipment OR SHOULD ONE? i.e. is it sufficient just to ground the thing via whatever case grounding comes with the thing? I'm worried that if I specify the electrician to do it, they'll damage the outer skin of the unit?

 

[petersonra]

How should one specify lightning protection on roof top equipment OR SHOULD ONE? i.e. is it sufficient just to ground the thing via whatever case grounding comes with the thing? I'm worried that if I specify the electrician to do it, they'll damage the outer skin of the unit?

Look at it this way. How many roofs have equipment located on them? How many of those pieces of equipment get hit by lightning? Ever?

In any case, just grounding the equipment, no matter how big the conductor is will not provide any significant protection against lightning.

 

[kwired]

I think you are either providing lightning protection for the entire structure or you are not. Trying to protect one item on the roof is futile.

Is not something the typical electrician would install. Would be installed by someone that specializes in lightning protection.

 

[synchro]

On a visit to the Chicago Air Route Traffic Control center I noticed many large diameter copper cables draped down from the roof on all sides, with no attempt to conceal them in any way. That's probably what it takes to have a real impact in reducing the likelihood and extent of any lightning damage.

 

[don_resqcapt19]

How should one specify lightning protection on roof top equipment OR SHOULD ONE? i.e. is it sufficient just to ground the thing via whatever case grounding comes with the thing? I'm worried that if I specify the electrician to do it, they'll damage the outer skin of the unit?

These guys offer a free class....have thought about going to it, but haven't so far.

Harger University | Harger Lightning and Grounding

Harger's Lightning Protection Installation Class is an approved continuing education course in the electrical field by several states. By attending, electricians licensed in these states can earn hours necessary for license renewal. Harger submits all paperwork to the state and covers all fees...

www.harger.com

 

[paulengr]

Part of the issue is keeping the surge impedance low enough to make lightning rods effective. Outside of that, ANY grounded conductive object is effectively a lightning rod. Concrete and steel building construction makes the whole building a very effective lightning protection system. It is not futile to protect individual equipment. For example a static line if it is run over the top of phase conductors on a pole line makes a very effective lightning protection if it is mounted high enough.

So the reason you rarely see anything is it already provides excellent protection. It would be a different story on an all wood building.

 

[mshields]

Tremendously helpful as always - thank you everyone!