2024 PIC lightning analyses and possible solutions

lightning storm 4-5pm friday july 12 2024. damaging 

1. possibly 2 projectors ($7265/₱480k each), 
2. outputs 8-16 of Behringer X32 digital audio mixer (php265k), 
3. 10 power speakers (18k-50k each), 
4. power amp located at PIC of speaker in gazebo (with wires hanging on trees)
5. 2 hdmi fiber cables (php 3.5k-5k each), 
6. hdmi matrix (php8k), 
7. hdmi splitter (php 2k)
8. led light (~php 300).
9. some power supplies (php150) and 
10. TOTAL ₱1595k

based on the damaged equipment and the wires between them, the lightning seems to be in the north-east of the building.

observations:

1. no lightning arresters
2. no SPDs on power line coming in
3. big long and wide building seating 1800
4. no dedicated grounding in most power lines
5. snake cables not grounded
6. ungrounded speaker cable, and no SPDs going outside building across trees to gazebo.
7. ungrounded speaker cable, and no SPDs going to roof speakers
8. projector power was on the same winding of the undamaged audio mixer connected to the (undamaged) amplifier that fed the outside speakers up on the roof.

references:

1. https://www.bicsi.org/docs/default-source/conference-presentations/2018-fall-conference/grounding-and-bonding-beyond-code-minimums-can-avoid-downtime.pdf?
2. http://www.atmo.arizona.edu/students/courselinks/spring13/atmo589/ATMO489_online/lecture_20/lect20_lightning_protection_structures.html
3. https://www.business.att.com/content/dam/attbusiness/prime-access/customer-requirements-at-cell-sites.pdf
4. https://lightning.org/lightning-protection-overview/

solutions in order of importance:

1. lightning arrester system (since the roof is galvanized, system should not be copper, but aluminum/stainless/galvanized, because "runoff water from copper or brass surfaces can contain enough dissolved copper to cause rapid corrosion")
1. size of earthing (copper) cable (aluminum ₱17/m) = 58mm2 (9.x mm diameter) according to code. (php17k/100m). #2 for ground ring, #6 elsewhere (according to AT&T Cellsite standard).
2. protection radius? = needed every 20ft according 
3. top of the church end-to-end and over the posts end-to-end. 
4. every 50ft. side of church every 20ft.
5. ground on 4 sides. 
6. church is 15m tallest, 3m lowest, 42m long, 40m wide. 
7. slope from center to side is computed at 25m. 
8. total length grounding cable (25*4 + 42*3) = 226m.
9. each 100m is php17k. extra will be used to bond with other existing ground rods (coms, power supply input, equipment ground, and water pipes)
10. 4x 8ft copper ground rods (php 1050 each 10ft) (php 890 each), (galvanized (for aluminum system) )
11. lightning arrester (php2580/pc)
2. put SPD (php 159-480) on line (after the breaker) coming in after breaker in studio/tindhan/avbooth
3. put SPD on speaker outdoor wires going to roof and going to gazebo OR use wireless to gazebo.
4. add ground wire to projectors
5. put electronic over/under voltage protector (php500) on power line
6. make sure avbooth grounding is less than 5 ohms.
7. use pure fiber for long hdmi transmissions (instead of fiber hdmi that has power included). php 3k https://shopee.ph/product/196709901/4606457288
8. put grounding rod (php285) and SPD on north east side speaker power strip. 
9. bond with south east ground.
10. assess how much lightning protection the building frame 
11. protect also the 2 High Volume Low Speed Fans (php600k each), and 2 projectors (php433k each) with lightning arresters 25 ft apart on top of church.
12. protect speakers with lightning arresters on the edges of the roof, on top of the pillars.
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question:

how much of these to implement?

beyond us:

1. exothermic bonding (php15k) (AT&T cellsite standard). but code allows bolted clamps.

related experience:

1. lightning hits naga view adventist college auditorium damaging some of my video production equipment