Lightning strikes / Surge supprssor

[102 Inspector]

Our municipal park is located at the end of the POCO line and was hit with lightning surge 2 years ago that took out the lawn irrigation system. They replaced it and added a surge supressor for the 3 phase service and additional grounding was added to the building that housed the equipment. This past summer is was struck again with a power surge that took out the surge suppressor that was installed. Since municipalities have no money, I am curious if there is something else that can be added to provide additional protection or is there something the POCO can do to protection the system. Have not talked to POCO yet, but thought there might be some suggestions here first. Thanks in advance.

 

[Hv&Lv]

The arrestors will not stop lightning. They are overvoltage protection for the POCO. Once the voltage gets so high, the arrestors allow the overvoltage to spark over and go to ground. Simply put, they help the lightning get to the earth from the lines.

The lightning needs to dissipate throughout the earth, but when there are low resistance wires buried all over, as in a sprinkler system, it will travel along these wires to somewhere where it will go to ground, usually at an end, (either end) where damage occurs by traveling to ground through the equipment, either burning or blowing the equipment out or up.

Underground wires, yours or POCO's are lightning attractors. Actually, if your ground rod resistances aren't low enough they can act as a current gatherer, rather than a dissapater.

Now about your system, is it grounded properly, have you tested the resistance, and do you have surge arrestors on your equipment? You stated you had additional grounding added, what did you do or add?

The end of the line is the worst place for lightning damage, both for the POCO and the customer. Don't expect the POCO arrestors to protect your equipment, you need some protection of your own.

 

[iwire]

Actually, if your ground rod resistances aren't low enough they can act as a current gatherer, rather than a dissapater..

:?:?

 

[ptonsparky]

If the surge arrestor was destroyed and your irrigation system is functional, the arrestor worked. They are supposed to sacrifice themselves.

Budget the moneys, raise taxes, or shut the sprinklers off. Watering the lawn just means some one has to cut it. Probably uses up some "weed & feed" to.

I agree with Iwire's :?:?

 

[Hv&Lv]

If the surge arrestor was destroyed and your irrigation system is functional, the arrestor worked. They are supposed to sacrifice themselves.

Budget the moneys, raise taxes, or shut the sprinklers off. Watering the lawn just means some one has to cut it. Probably uses up some "weed & feed" to.

I agree with Iwire's :?:?

OK, Your sprinkler system is run throughout a golf course, with ground rods tied to your system in a couple of places as an attempt to limit damage to your system. The POCO dead end pole has a ground rod or two at the base of the pole. Draw an incomplete circle with a dot about 1/4 the way from one end. The dot is the control house where the service entrance and breaker panels are located. At the end closest to the dot is the dead end pole with a ground rod or two. from the dot to the other end of the circle is the sprinkler system. A couple of ground rods were driven along the system along with a ground rod driven at the end of the system. (other end of the circle). This was done because of previous lightning damage.
After a bad lightning storm (almost every storm), there would be damage to the sprinkler system. Sometimes the arrestor was blown, sometimes not. Apparently the lightning would cause overvoltage to the line, sparking over the arrestor (like it is supposed to) and going to ground. Because the the last ground rod(end of the circle) was driven appx. 50' from the pole, when the lightning went to ground, the last ground rod in this sandy soil would "collect" the current, sending it back up the line to the control house.

 

[jim dungar]

Don't forget that there is no single item called a surge suppressor no more than there is something called a circuit breaker. For example, I am pretty sure that a surge suppressor strip for your computer, would not 'do the job' protecting the irrigation system very well in the Tampa Bay FL area.

There is a reason some devices cost $100 while others cost $1,000. Surge Suppression used to be a ripe market for scammers partly because it is as much art as it is science.