Megger Protocol
Megger Protocol
OK, I visited the site, and here is what I found:
The water heater was gas. It has a metal flue pipe that extends through the roof for its exhaust. The lightning hit that flue, and traveled down, where it jumped to the tank. From there, it went down to the gas valve, and jumped to the CSST gas pipe. Since there was a gas boiler next to the water heater, it also jumped to that unit, probably thru its gas pipe from an adjacent gas piping manifold.
FROM the boiler furnace, it got into the building's electrical wiring. It also started a structure fire at the boiler's junction box where it was attached to the wooden studs.
This was all on the 2nd floor of a 2 story house, in a utility room that contains both the water heater and the gas heater/boiler units.
The owners were at home at the time, the wife cooking dinner. The gas range also took a hit, its electronics poofing out with a big bang. Scared the woman out of her wits! Needless to say, she quit cooking dinner, with the stove being inoperative now.
Within a few minutes, the smoke detectors started howling, since the upstairs utility room was on fire, although barely started at this point.
The husband went upstairs to investigate, since the top floor smoke alarm had started bleeping first, and he discovered the utility room full of smoke! He yelled to his wife to call 911 and get out of the house! He took a fire extinguisher and managed to put out the fire -- which was small enough to do so at this time -- before fleeing the house himself.
The fire dept arrived and confirmed the fire was out. They also ensured that the gas service was cut off.
Post-fire investigation revealed that the CSST ended up with pinhole leaks in it, blowing out from the lightning. The gas pipe manifold was not properly bonded, since the house was built several years ago right before the newer bonding requirements were implemented. The gas company refused to restore service until the pipe manifold was bonded back to the service panel.
The dishwasher also lost its mind, the electronics were fried by the surge. How it got involved with this is beyond me, it's not located anywhere near the range.
One of his TV sets blew out, and the cable modem was fried, too. I would expect these to suffer from a lightning hit, but there were 2 other TV sets and converter boxes that appear to be OK.
Nothing else seems to have been affected. All the GFI's are functioning properly, as well as the AFI breakers. The smoke alarms are working fine, as well as the doorbell.
The power company recommended the wiring be tested. This is where the megger comes in. The insurance company says to proceed.
It's my understanding that when testing a circuit with a megger, all utilization equipment must be disconnected, isolated, etc. or else the high voltage spike can cause damage.
When testing a lighting circuit, for example, how do you deal with the insulation detectors in a recessed light? Some of them act as a switch, while others utilize an element of sorts, and have a neutral connection. Would a megger test affect this? Or do you simply keep all the wall switches "off" and leave the bulbs in place?
Comments and observations welcomed.
