Static Electricity at marina with gas dispenser and new tech decking

[Kohlhase]

Please help - never run into something like this before.

I have a customer that installed new decking last fall and we upgraded his gasoline leak detection system and added new sumps under existing dispensers. We got a call that people were being shocked at the dispenser. We sent our technician up and he was getting shocked too so we shut off the main on shore so everything had no power and still getting shocked. Long and short we have had several electricians on site power company shutting off underwater feeds to islands and still getting shocked.

All grounding was checked for loose connections all over the place and neighbors properties were shut off too and still getting shocked.

It isn't just at the dispenser it is along the dock too that people are being shocked.

The shocks only occur during dry weather. Once you touch the dispenser the spark jumps about a 1/2" before even touching and then nothing if you don't move and touch it again. Leads us all to believe it is static from the new decking.

What are some solutions to get rid of this static charge besides replacing $50k worth of decking?

 

[ELA]

There are electrostatic voltmeters you can purchase to measure the charge present on a person after walking on the deck. This would help you confirm if the "action of walking on the deck" is the static generator.

If the friction of peoples shoes and the deck material are generating the static charge it may be difficult to eliminate over the entire deck area without changing the deck material.
You could locally dissipate the charge by adding dissipative materials but that may not be good enough?

 

[Pierre C Belarge]

How about adding some kind of copper mesh along a portion of the deck, with a conductor dropping into the water below the deck?

 

[tom baker]

It takes very little to disspate a static charge, IE the resistance can be quite high. Think of the rubber straps dangling from cars for static control.
Is this fresh or salt water? Fresh water is a fairly good insulator.

 

[Fulthrotl]

Please help - never run into something like this before.

I have a customer that installed new decking last fall and we upgraded his gasoline leak detection system and added new sumps under existing dispensers. We got a call that people were being shocked at the dispenser. We sent our technician up and he was getting shocked too so we shut off the main on shore so everything had no power and still getting shocked. Long and short we have had several electricians on site power company shutting off underwater feeds to islands and still getting shocked.

All grounding was checked for loose connections all over the place and neighbors properties were shut off too and still getting shocked.

It isn't just at the dispenser it is along the dock too that people are being shocked.

The shocks only occur during dry weather. Once you touch the dispenser the spark jumps about a 1/2" before even touching and then nothing if you don't move and touch it again. Leads us all to believe it is static from the new decking.

What are some solutions to get rid of this static charge besides replacing $50k worth of decking?

two things come to mind, and as you say, static properties of the decking
seem the most likely culprit.

the other one's a long shot. if you've got a boat with bad electrics, it can be
dumping power into the water. is it occurring everywhere the new decking is
at, or is it near one point specifically? if it's a boat with a bad inverter, it can
be putting out power into the water from the batteries even if the whole dock
is turned off.

a simple test to see if it's the dock is to drop a bare #6 wire in the water, and hold
onto it while walking back and forth. you'll stay grounded, and should not spark.

unfortunately, that test could be very hazardous if you have a boat putting
power in the water. lethal even, so you can't do that one as a test.

here's something i posted on a differenent thread about dock power....

"i worked on one dock box that the boat connected to it was pulling about
8 amps on a 220 volt non gfi protected circuit, and that was going thru the
aluminum hull of the boat (65' chris craft) and being dissipated in the surrounding
water.... aside from the wasted power, and shock hazard, it was eating up all
the zincs on every boat within a couple hundred feet. that was why they
called for service.... guy lost all his zincs, and a prop in two weeks."

 

[sgunsel]

If you are getting a 1/2" spark, you have a significant safety hazard, not just a nuisance. $50K for a new deck isn't as bad as a fire/explosion. That spark is definitely capable of igniting gasoline vapors when present in a flammable concentration, which WILL occur at some time during fueling. Anyone walking up to and touching the grounded nozzle, hose, or a gas can could cause ignition. Most surface treatments are very temporary and rely on atmospheric moisture, although there may be conductive coatings that could provide longer term protection. It sounds like a poor choice was made on decking material. Wood and concrete have some advantages over plastics, at least for static electricity dissipation.

 

[weressl]

Please help - never run into something like this before.

I have a customer that installed new decking last fall and we upgraded his gasoline leak detection system and added new sumps under existing dispensers. We got a call that people were being shocked at the dispenser. We sent our technician up and he was getting shocked too so we shut off the main on shore so everything had no power and still getting shocked. Long and short we have had several electricians on site power company shutting off underwater feeds to islands and still getting shocked.

All grounding was checked for loose connections all over the place and neighbors properties were shut off too and still getting shocked.

It isn't just at the dispenser it is along the dock too that people are being shocked.

The shocks only occur during dry weather. Once you touch the dispenser the spark jumps about a 1/2" before even touching and then nothing if you don't move and touch it again. Leads us all to believe it is static from the new decking.

What are some solutions to get rid of this static charge besides replacing $50k worth of decking?

http://www.gndzero.com/grounding_chemicals.phphttp://www.gndzero.com/
http://www.techspray.com/staticcontrol.htm

 

[LJSMITH1]

This sounds exactly like static electricity, because the voltages needed to create a 1/2" spark are 10,000vdc and up (depending on your body's resistance)

IMHO, the only easy way to resolve this issue is to place some ESD anti-static rubber mats in and around the dispensers or anything else that allows the discharge. Once you step on the rubber mat, you should be insulated from the decking enough to dissipate the charge. Any antistaic sprays or chemicals, will probably be very short term solutions, as the outside conditions (dew, rain, UV, etc.) will tend to dissipate the chemicals rather quickly.

Aside from that, there is no other solution as the plastic decking is non conductive and cannot be 'grounded'. The static electricity is created by walking on the deck and the human body storing the static charge just like a capacitor. The ambient conditions are critical to make this work (i.e. low humidity, dry, etc.). When the deck is new, it will have a higher propensity to create static charges than after it is weathered.

Here's an interesting link with FAQ's on static electricity: http://amasci.com/emotor/stmiscon.html

The following is from American Plastic Lumber, Inc's website:

In certain weather conditions, it is possible to experience the effects of static electricity with American Plastic Lumber HDPE material, especially when the material is new. This is similar to the static shocks experienced when walking across a carpet in dry weather and touching a metal doorknob. We do not warrant against static electricity, as it is a natural phenomenon and not a sign of a product defect

Here is a snippet from TanDeck's website:

Can static electricity be generated when walking across the deck floor?
Yes. In some instances, deck owners have reported generating static electricity when walking across their decks- similar to walking across a carpet in the wintertime. This is a naturally occurring phenomenon, and only occurs in very dry conditions and usually on newer decks. TanDeck uses anti-static agents in our decking to minimize this problem. Homeowners can dampen the TanDeck surface to eliminate this problem if necessary.

Try the mats.....they are fairly cheap and will be effective.

 

[ELA]

IMHO, the only easy way to resolve this issue is to place some ESD anti-static rubber mats in and around the dispensers or anything else that allows the discharge. Once you step on the rubber mat, you should be insulated from the decking enough to dissipate the charge. Any antistaic sprays or chemicals, will probably be very short term solutions, as the outside conditions (dew, rain, UV, etc.) will tend to dissipate the chemicals rather quickly.


Try the mats.....they are fairly cheap and will be effective.

Be sure to issue heel straps to all deck walkers as well
http://www.allmats.com/site/439205/page/504968

 

[LJSMITH1]

Be sure to issue heel straps to all deck walkers as well
http://www.allmats.com/site/439205/page/504968

Ha! Thats only if they touch each other while they are walking..

The mats will work to eliminate the uncomfortable and potentially hazardous issue around the dispensers.

 

[ELA]

The mats will work to eliminate the uncomfortable and potentially hazardous issue around the dispensers.

Actually what I meant by that was that the mats are not likely to work unless people have a means of conduction from their body to the bottom of their shoes. Which of course is impractical at a marina.

When walking in shoes that are insulators, and these rub against an insulator surface (like the deck) -then static is generated. They are already charged when they step onto the mat. They now need a discharge path into the mat (thus the shoe strap joke).
Otherwise their bodies will remain charged until they touch something they can discharge into.

 

[LJSMITH1]

Yes..I understand. However, if the mats are in place, they should help reduce the amount of charge buildup on the approach to the dispenser and thus the discharge potential. To completely eliminate the charge from the body, you would have to use that heel strap or a wrist strap to normalize the charge potential. Both of which (I am assuming), are not practical for this application.

The only other temporary solution is to install a fine water mist spray system that will keep the decking damp during the day or on low humidity situations. This will neutralize the charge potential of the new decking. Plus it may be a welcome cooling effect during a hot summer day!:grin:

 

[TwinCitySparky]

It sounds like a poor choice was made on decking material. Wood and concrete have some advantages over plastics, at least for static electricity dissipation.

I agree. Most cost effective approach would be to just replace just the hazardous area with wood decking. If they understood the danger they would spend the money and do it right. (Assuming it is a static problem)