Lightning Protection for Control Panel??

Hi,

I am using Nema 3R control panel for my PLC, HMI and other 120V stuff and we are not planning on providing shade structure for that panel. I was wondering if I need to have Lightning protection for my control panel??

Thanks

That's like asking how much money is enough.

Is your area prone to lightning?

Where is the panel in relationship to other things, like trees, poles, etc that could recieve a strike and flash over.

Do you have any surge protection?

My new standard as of a few months ago for custom panels, right next to the Sola Basic 24 vdc power supply is their new new "matching" surge suppressor.

If it is a very simple panel, take your chances, If you got some expensive stuph in there, then you need some insurance.

regards.....casey

I concur. A 120V DIN mountable surge protector will run you around $100. A small price to pay for insurance. Thing to remember, a direct lightning strike, not so common, a spike coming through the power line, very common.

Then on the other hand, I have a 16 point analog card that costs $600. Am I going to spend $1600 to protect all those points? No. But I will spend X dollars to protect those points which I consider high risk.

anks said:

...and we are not planning on providing shade structure for that panel ....

Click to expand...

That's OK - a shade structure will not protect your panel from lightining strikes anyway.

Add a surge buster as identified above, and make darned sure you have a good ground - water pipe or deep ground rod. A near field strike or a direct hit will take out your panel no matter what you do, but a good surge protector will take care of most transients.

On one of my trips to GE Factory Training, circa 1980+/-, was a special class given in lghtning protection and avoidance.

Rule One - You can't stop lightning

Rule Two - You can't prevent damage

Rule Three - You CAN minimize damage, almost completely

All grounding wires should have sweeping radii, NOT sharp bends

There should be a smooth flow from the grounging point to ground, not going "backwards" after a bend

Lightning likes the path of least resistance, and will readily jump over an obstacle or to another path of lesser resistance

A cord with six knots is an ideal lightning suppressor for something like a computer. This was first discovered by accident when an owner of a window air conditionef=r called in for a replacement line cord. Seems his had a single knot in it and lightning hit the power line and blew out the side of the cord, rather then trying to foller the strands around in a circle. AC unit was fine otherwise. All other appliances were "toast", including the toaster.

Phone line protection can be as simple as two 100 ohm resistors in series with the phoneline.

An on and on and on.

Lots of simple stuph that worked well.

The knoted cord was upgraded to wraping a flat 3 conductor cord around a wood dowel. Had lots of them "smkoked" at two way radio sites.

As Tom mentioned, a good ground. A 10 foot ground rod and some #4 copper wire with a clamp will be under $20 dollar, and wel worth the cost. Provides additional safety in the cabinet, 'specially if you have it hooked up to a GFCI outlet for use with power tools or test equipment.

regards.....casey

Lightning Protection & Grounding Comments

I don't know what you guys mean by a "shade" structure. This term is not mentioned in the Lightning Protection manual. There are rods, masts, and overhead wires. The overhead grid (Faraday cages), conected to grounding systems, are the preferred method at ammunition plants. When you are working at a reactor that makes TNT, C4, or (God help you) even nitroglycerin, then you want the best lightning protection that you can build. The Army Materiel Command long ago decided that the overhead wire grid system is the best method. The idea is to intercept a strike BEFORE it hits a critical point. To do this your grounded wires must be several feet above the building being protected.

Speaking of grounds, the Ufer ground method will provide a much lower resistance than any 10' single rod, and usually at a lower cost.