[toeknee]

Any suggestions on keeping my board from going out during bad electrical storms? 2 boards in 3 years. Surge protectors?

[wmproop]

This does sound out of the ordinary,, are they being put in correctly? They need to be handled with kid gloves,avoid touching the circuits on the back, the salt from your hands can take away from the life of printed boards. Also is the furnace in a very damp area? Dampness is bad do all you can to controle dampness

[toeknee]

any suggestions on keeping my board from going out during bad electrical storms? 2 boards in 3 years. Surge protectors?

The unit is my attic, very dry up there, install is correct. It just seems that the circuitry is very sensitive or our thunderstorms are extremely intense, or both. The last storm on Sat. a lightning bolt struck a pine tree in my front yard, about 40 ft. from my front door. No other appliances or clocks, etc were affected. I realized a few hours after the storm that my outside unit was on and not my inside. The small LED indicator was on (not flashing) and the fuse on the board was fine.? No blower.

[KISS]

Take a look here:

Citel Surge Protectors and Lightning Protection for AC Power Lines - Surge Suppression for Single Phase Circuits, Cellular and Wireless Base Station, Main Electrical Panels - NEMA Enclosures

In your case, you may want to invest in both a Whole House Surge Protector and a local one for the furnace. Look around. Key terms "whole house surge protection" "equipment surge protection".

And yes, they could be sensitive to static, line voltages or EMI/RFI. I was VERY surprised that a recent module Carrier furnace has nothing to protect it. It's blower was also activating X-10 modules until I put a filter on it.

Too bad, we can't get schematics for these things, other wise they can be fixed at a lower level as well.

[toeknee]

I'm curious as to how much static can possibly conduct through my heater stack that sits on the roof.

[KISS]

What ind of stack are we talking about? Metal, plastic, chimney?

How well is the system grounded, if metal parts are exposed? Ground rod?

[toeknee]

Metal stack, 2-3 ft. projection. Grounded through normal electrical circuit to panel.

[KISS]

This should basically suggest very highly that the lightning jumped from the tree to the house. The tree took a direct hit and the furnace took an indirect hit from the tree.

Lightning rods are pointed because a sharp point has a much higher field strength in terrms of volts/sqmeter. If you had a 10K volts with a pin head or 1 mm or 10K V with a plate of 10 m X 10 m, it's going to strike the pointed tip first. Any sharp points on your metal projection needs to be removed. Rounded corners only.

I really think you should invest in a lightning protection system as priority #1, An equipment surge protector as priority #2 and a whole house surge suppression system as priority #3. Good low impedance grounds are mandatory for direct strikes. The lightning rods will bleed off the atmospheric charges before they can do damage.

Lightning rods will bleed off atmospheric charges and divert strikes controllably to ground.

The use of a whole house supressor will tend to divert lightning strikes to an overhead power line to ground and offer protection when utility power is briefly restored.

An equipment surge supressor will do a secondary job of protecting the equipment by clamping power line transients entering the equipment.

I can relate a story about an inexpensive piece of scientific equipment which kept dying. There was no protection inside the equipment and it would cost about $3k every time it broke. When I asked the company about it, they said "The specifications state that the instrument should be connected to a 120 V 5% 60 Hz source, and it wasn't, therefore we are not responsible for any damage."

The bottom line is that surge protection devices are expensive.

I had another piece of equipment which was operated next to a blinking 1000W lamp and the blinking light kept taking out a thermocouple scanner. When I obtained the schematic, the regulator that was designed in the product wasn't even populated. I added a $2.00 worth of parts and it continued to work. Multiple units kept breaking.


NASD: Lightning Protection for Farms