Lightning and Surge Protection for HVAC Equip? 1

[Roktgr]

Hello,

I work at a small hospital and am looking for some information on surge and lightning protection. Bit of background, last summer we had one confirmed and possible one other, unconfirmed, lighting strikes to the hospital building. It damaged a number of HVAC control boards and several AHU motors.

We have just got a new HVAC controls sytem installed, have repaired the damaged boards and are in the process of upgrading the rest of the system to newer components.

Obviously we would like to install some sort of protection first on the HVAC components and possible on the AHU motors.

My first recommendation would be a lightning arrestor or diversion system, but my supervisor doesn't think they work, that they attract lightning, and are maintenance intensive. It has been discussed at length and is not an option at this time.

My second recommendation is to install a surge unit on each HVAC component but I have limited knowledge of the different types of units and which would be the most effective. I know there are capacitance, inert gas, and resistor type surge protectors but not much beyond that.

Does anyone have an reference materials or sources that I could read up an try to determine which style of protection would be best suited for the application? Suggestions would be welcome as well.

My supervisor is pushing very hard to install some of the office depot/home style surge protection devices, but I don't think they will do much of anything against a large surge such as lighting. Supervisor doesn't understand why this is and thinks it would have to provide some sort of protection. I would like to have a alternative solution to suggest. Thank you.

 

[dpc]

http://www.us.schneider-electric.co...A17005D5766/$file/surgeprotectionFrameset.htm

If you get copy that long URL, take a look at these products. GE has similar devices. TVSS (Transient Voltage Surge Suppressors in the UL/industry terminology for these devices.

For best protection, you'll want one at the service entrance, and additional devices at the equipment you are trying protect. They should be as close as possible to the HVAC equipment being protected. They also need a good ground connection - as short and straight as possible.

But.... if a rooftop HVAC package takes a direct lightning stroke, there is nothing that is going to protect it.

Franklin-style lightning rods and lightning protection system do work, but it still would not eliminate the need for some type of surge protection.

 

[rbulsara]

A good lightning protection system installed per NFPA 780 is essential part of overall surge protection.

Contrary to the myth a properly installed LP system does not attract lightning, but would safely "discharge" the electric charge being built in the air/clouds so that the electric potential between earth (rod) and the surrouding (generally cloud or air) will not build up high enough to cause a lighting strike in first place. (It is true that in extereme and unique cases direct lighting strike may overwhelm any system but not installnig a LP system is no protection)

The key word is properly installed, which includes roof top HVAC unit protection and properly sized conducotors.

Along with this local TVSS would get you desired protection.

On top of this if the controls are very sensitive there are TVSS available for control and even telphone circuits that can be installed for all conductors leaving/entering the building.

TVSS are no substitute for Lightining protection. They also protect against surges caused by switching etc, which are not related to lightning.

 

[lansford]

Why don't you give one of the underutilized consutants some of whom are low on work, some business and hire them to prepare a report with recommendations for your project?
JIM

 

[rbulsara]

True. I hate givng free advice..but once in while it slips out..

 

[Roktgr]

Free advise huh so what is the purpose of Eng-tips? I only asked for places to find information, if someone wanted to make suggestions that was fine but was not what I primarily asked for.

We have a project to have a local company do an evaluation of our system and provide a report of recommendations but being part of the Federal government that project has been waiting for funding for 8 years now. Not much I can do about that.

Thanks to those that provided some information for me to look at.

 

[bilikk]

answer to Roktgr
in order to help you about that matter, i will recommand you to read one chapter (chapter J) of the Electrical Installtion Guide written by Schneider experts called protection against voltage surges in LV : it gives practical info about what is it, the devices for protection and how to select ...

http://www.electrical-installation....pdf_files/EIG-J-protection-voltage-surges.pdf

 

[bilikk]

answer to Roktgr
for Lightning & surge protection it is of value to come back to technical basics

http://engineering.electrical-equipment.org/electrical-distribution/lightning-surge-protection.html

 

[nawao]

You can download a lot of very useful information from this site:

http://www.hakel.com/