Estimating an residential lightning strike

[MagnoliaElec]

Next Tuesday I'm scheduled to go out and ck out a house that has been struck. the HO says over the phone that everything in the house blew, micro range phones computers you name it it got hit in the house. I'm a little leary given the amount of behind the drywall damage that maybe there. I'm open to any advice that the forum may have for me. Things to look for or questions to ask

 

[480sparky]

One word: Megger.

 

[quogueelectric]

I would allocate a day or two to physically examine as much as possible and keep good records of exactly what and how much time was spent on inspection. pull out devices and check bussbar and breakers. I would try to replace all breakers.

 

[jack cay]

i have done 3 of these so far. definetley Megger. check for bus damage. and remember lightning travels at the speed of light at all frequencies, this usually knocks out all cordless phones. i have had one that just zapped the phone wires. also check for blowout at the recepts and switches (usually visable on the cover). but definetly one of the most difficult things to give a HO a estimate of potetial damage.

 

[electricguy61]

i have done 3 of these so far. definetley Megger. check for bus damage. and remember lightning travels at the speed of light at all frequencies, this usually knocks out all cordless phones. i have had one that just zapped the phone wires. also check for blowout at the recepts and switches (usually visable on the cover). but definetly one of the most difficult things to give a HO a estimate of potetial damage.

Fast, but not the speed of light (186,000 per second)

 

[brian john]

Megger and T&M

 

[MagnoliaElec]

A great deal of our business comes in the form of T&M. I'm ever so thankful for handymen and the disasters they leave behind. T&M is definately the way to go on this job. Any thoughts on dealing with an insurance company?

 

[brian john]

Your price is your price do not let them try to negotiate with you, as they try to cut your cost explain you forgot to add in travel, fuel surcharge, tool rental, meal expenses ladder pay.

 

[mdshunk]

Remove every branch circuit conductor from its termination in the panel.
Remove all lamps in the house
Unplug all cord and plug connected loads in the house
Remove all dimmers and wirenut line to load
Remove all GFCI receptacles and wirenut line to load.
Turn all single pole switches to the 'on' position.

Megger check all the branch circuits hot to ground and neutral to ground. Investigate and correct any non-conformities at this time. (do not megger hot to neutral or hot to hot yet!).

Megger check at low voltage hot to neutral and hot to hot (for the 240's). Investigate and correct any nonconformities or disconnect any forgotten loads. Recheck at low voltage to confirm that all loads are indeed disconnected. Now you can do your full voltage check hot to neutral and hot to hot.

Loads you're likely to overlook are attic fans, chime transformers, underground feeds, furnaces, dishwashers, well pumps, etc. These loads still need checked hot to ground and neutral to ground to evaluate for the need of possible replacement. Don't megger a load hot to hot or hot to neutral unless you want to buy it. Make sure your bill or invoice specifically disclaims anything to do with any cord and plug connected loads.

Naturally, you'll want to visually examine everything. Some problems will be highly visible and obvious. A good number of years ago I was on one her the panel cover was blown free of the back box; screws stripped clean off. A shopping center had the breaker for the parking lot lights blown to smithereens. Here's a set of switches from one more recently:

 

[satcom]

Remove every branch circuit conductor from its termination in the panel.
Remove all lamps in the house
Unplug all cord and plug connected loads in the house
Remove all dimmers and wirenut line to load
Remove all GFCI receptacles and wirenut line to load.
Turn all single pole switches to the 'on' position.

Megger check all the branch circuits hot to ground and neutral to ground. Investigate and correct any non-conformities at this time. (do not megger hot to neutral or hot to hot yet!).

Megger check at low voltage hot to neutral and hot to hot (for the 240's). Investigate and correct any nonconformities or disconnect any forgotten loads. Recheck at low voltage to confirm that all loads are indeed disconnected. Now you can do your full voltage check hot to neutral and hot to hot.

Loads you're likely to overlook are attic fans, chime transformers, underground feeds, furnaces, dishwashers, well pumps, etc. These loads still need checked hot to ground and neutral to ground to evaluate for the need of possible replacement. Don't megger a load hot to hot or hot to neutral unless you want to buy it. Make sure your bill or invoice specifically disclaims anything to do with any cord and plug connected loads.

Naturally, you'll want to visually examine everything. Some problems will be highly visible and obvious. A good number of years ago I was on one her the panel cover was blown free of the back box; screws stripped clean off. A shopping center had the breaker for the parking lot lights blown to smithereens. Here's a set of switches from one more recently:

Marc, I can send him pic's of cable blown apart in the wall, it looks like a spent firecracker, megger testing will usually locate the faulted cables.

For insurance jobs, we usually present a one quote on the cost of testing, and another for the work to be done.

 

[mdshunk]

 

[masterinbama]

the black marks on the wall sure make trouble shooting easy. Went on one the other day tripping breaker feeding some can lights in a bar. all the cans were in a sheetrock ceiling wich we all know makes cans fun to take apart. Got to the 7th can pulled the bulb and it was black inside. After having taken 6 cans apart it turned out to be a bad bulb in 27 years I had never seen a bulb dead short like that.

 

[ohm]

Take before & after pictures, record temperature & humidity along with the megger readings. Megger a new 250 ft. coil of NM before you start, so you will know what is normal. Ohm out appliances and record nameplate data, age, & original cost of damaged units for the insurance company.

After rewiring install a 100 W lamp in series with the breaker with small loads. If the load is 100 W it should have a steady orange glow. Use a larger lamp for larger loads. If the switch to the load is off and the lamp glows, to have a shorted circuit.

Remember, lightning hates to make a sharp turn in a wire and will often leap off the wire to a grounded surface.

T & M w/ no guarantees! Good Luck!

 

[nafis]

i was reading your replies and that make me wondering what megger you guys use . i do not have one yet and never used one . but that is going to be on my xmas list

nafis

 

[mdshunk]

i was reading your replies and that make me wondering what megger you guys use . i do not have one yet and never used one . but that is going to be on my xmas list

nafis

Depends on what you're going to use it for, but if you don't own one already, anything you get will be great. Check out the Fluke 1507, maybe.