Odd Lightning Choice

[barry lauer]

Three Goodman A/C units, side by side on separate concrete bases. Almost once a year a thunderstorm will generate a 'close strike' (thunder and flash together); however, only one of the A/C units will suffer damage (blown contactors, capacitor). Expensive and frustrating as to why it happens to only a single unit at each (storm) occurrence (and, I believe to the same (middle-placed) unit. Home is 20 yrs. old, two-story with a basement. Besides fast losing my Christianity and growing to believe in bad luck, any thoughts advice would be appreciated. Barry

 

[LarryFine]

Welcome to the forum.

The lightning has two basic possible pathways into the unit, through the wiring or the earth.

Most likely, IMO, the earth and thus the housing become energized, causing internal arcing.

It's only one unit because that one arcs first and protects the others like a surge protector.

 

[barry lauer]

Thanx, Larry! Helps explain why just one unit (and not everything else). If you don't mind me asking additionally - Are there practical, affordable solutions available aside from sincere, fervent prayer? Barry - Engineering Energies LLC, Greenville SC

 

[hbiss]

I assume all units are fed from the same panel? There are air handlers in three different locations? I would suggest that the location of the associated air handler and duct work is susceptible to the EMP pulse and conducts it to the condensing unit through the line set. That unit wouldn't be for the top floor would it?

-Hal

 

[ramsy]

Are there practical, affordable solutions available aside from sincere, fervent prayer?

Industry standard always relied on electrode bonding integrity, or adding more bonding points.

The last few NEC code cycles mandate level-1&2 SPD, and more HVAC installers wont warranty equip. without level-3 or 4 at FAU / evaporator.

 

[barry lauer]

I assume all units are fed from the same panel? There are air handlers in three different locations? I would suggest that the location of the associated air handler and duct work is susceptible to the EMP pulse and conducts it to the condensing unit through the line set. That unit wouldn't be for the top floor would it?

-Hal

Hi Hal - Thanx for the helpful comments. The two handler/heat units are in the attic and service the 2nd and main floors; the other is in the basement (for the third Goodman unit outside). I'm from 'up North' (Pittsburgh, Cleveland) and only had to worry about a single heat/AC system, so this is a bit new to me. My thought on all this is to install some sort of grounding system on the outside unit(s) or the one that seems to get hit more often; however, I have no experience regarding 'lightning suppression' systems other than simple 'lightning rods' we had on family barns. Barry Lauer - Electrical Energies LLC

 

[hbiss]

The last few NEC code cycles mandate level-1&2 SPD, and more HVAC installers wont warranty equip. without level-3 or 4 at FAU / evaporator.

This is where I would start. Easy enough to find information on doing it.

-Hal

 

[barry lauer]

This is where I would start. Easy enough to find information on doing it.

-Hal

Thanx again, Hal! Barry