Previous in Forum: Reliability   Next in Forum: Secondary Y-ph Earthing of Potential Transformer
Close
Close
Close
49 comments
Associate

Join Date: Apr 2009
Posts: 36

Forklift Operators Get Static Shock at Elevator Pendant

04/17/2013 3:09 PM

How do you find the source of static electricity?

Here's the situation:

Our forklift operators can open and close an elevator door by using a pendant control that hangs near the elevator (so they don't have to get off of the lift). Frequently, but not always, the operator will get zapped by electricity as he grabs the control. We have also seen a spark when the pendant control bumps the roll cage as the forklift is driven up to the elevator (before the operator grabs it). It seems to be static electricity because there is just one zap (I suppose it could also be a capacitor discharging?)

Details:

The elevator is big enough to lift/lower 2 forklifts (side by side) with loads. It has one hydraulic cylinder and only goes up/down 1 floor.

Both elevator doors (upstairs & downstairs) have controls on a wall panel and controls hanging from the ceiling on a pendant (just like crane/hoist controls). The upstairs pendant is covered with plastic and rubber with no exposed metal parts. The downstairs pendant is covered with metal. Both pendants will zap a forklift operator.

The forklifts are propane powered, have solid rubber wheels, and ground straps that drag on the floor (some are rubberlike, some are metal chain, some wirelike). Our plant is clean with epoxy covered concrete floors.

The operators say they only get zapped at the elevator (pendants and wall panel controls) and not at other pendants like roll up doors.

I'm trying to figure out what the source is: The epoxy floor, the forklift, faulty controls, hydraulics, etc.

What meters are available to measure static charges?

After I find the source, I should be able to fix this.

Thanks for your help.

Login to Reply
Interested in this discussion?
You can "subscribe" to this discussion to be notified of new comments.
Click on the Subscribe menu at the top of the page.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
2
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 29966
Good Answers: 809
#1

Re: Forklift operators get static shock at elevator pendant.

04/17/2013 3:42 PM

Increase the humidity in the area.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Login to Reply Good Answer (Score 2)
Guru
United States - Member - New Member

Join Date: Mar 2010
Location: In the pool because it is too hot.
Posts: 3055
Good Answers: 140
#9
In reply to #1

Re: Forklift operators get static shock at elevator pendant.

04/17/2013 10:24 PM

PW, I give you this GA because it is the only answer here that make sense.

To measure electrostatic charges there are special very expensive electrometers.

Victoreen and Keithley made these. Electrostatic charges occur when materials with high specific isolation resistance are used. To pick up some out of the OP's comment:

Dry air, Epoxy floor, Paint on the forklift, dry skin of the driver, cushion of the forklift, your forkflift tires, that for epoxy are also probably of a special material, otherwise they ruin the floor with black tire marks.

You can make a cheap electrometer yourself with a flat glass bottle, a cork, a metal pin as sensor and 2 strips of aluminum foil. the two strips and the sensor go in the botlle and when electrostatic charges occur the 2 alu strips come apart from each other on the free end. Use your imagination or try to find maybe a U tube presentation?

As long as the driver and that handle are not on the same electrostatic charge level there will be a equalisation of the charges, or a discharge.

Note that these charges occurs only on isolators and in dry air. Conductors almost have no electrostatic charges. They can only distribute them.

Other than bringing the charges, or the discharge together through the innocent hand of the dry driver, can be a metalized plastic guirlande, like used on the Christmas three around the neck of the driver, towards his hand.

That way he will not feel it anymore.

Discharging everything to your epoxy floor is also difficult.

You can try to "earth the handle" replace with something non plastic and also the rope.

If it still the same then your floor and air are the culprits.

A synthetic hair poppy is also a good electrometer or the hair on your chest.

Have fun.

__________________
Plenty of room here
Login to Reply
Guru
United States - Member - New Member

Join Date: Mar 2010
Location: In the pool because it is too hot.
Posts: 3055
Good Answers: 140
#39
In reply to #9

Re: Forklift operators get static shock at elevator pendant.

04/19/2013 4:04 AM

About five years of my career applied electrostatic charges was my business and my bread. There are many ways to create electrostatic charges and one application was electrostatic copier paper that was used everywhere from the seventies to make foto copies of documents.

Base carrier was high quality paper and as electrostatic isolator zinc oxide was used as coating. Because electrostatic charges do not disperse equally, a conductive layer was coated on the paper, under the zinc oxyde.

The copier machine rubber transportation rolls did not change the charge with contact. Neither did the petroleum based bath where it went through.

We charged also a lot if plastics, epoxies and other isolators. (insulators?)

So what is a technological need in one case, becomes a burden in the other. I gave a list of the build up points. Sometimes it is enough to wash the hands with some methanol alcohol to move the charge to a different place or spread it out. So does any other material that conducts (read transports, because a different isolator will upload also) the charge. If the driver e.g. puts on a metal glove, he will feel the spark where the glove contacts the skin on the arm.

__________________
Plenty of room here
Login to Reply Off Topic (Score 5)
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#2

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 4:14 PM

Put a plastic bag over the control.......or hand

__________________
Break a sweat everyday doing something you enjoy
Login to Reply
Guru

Join Date: Oct 2008
Posts: 42260
Good Answers: 1659
#3
In reply to #2

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 5:17 PM

It'll jump through that like it isn't even there.

Login to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#6
In reply to #3

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 7:53 PM

What about rubber gloves ?

__________________
Break a sweat everyday doing something you enjoy
Login to Reply
Guru
Popular Science - Weaponology - New Member Netherlands - Member - New Member Fans of Old Computers - Commodore 64 - New Member

Join Date: Sep 2007
Location: Japan
Posts: 2703
Good Answers: 38
#7
In reply to #6

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 8:44 PM

this works better

__________________
From the Movie "The Big Lebowski" Don't pee on the carpet man!
Login to Reply Off Topic (Score 5)
Guru

Join Date: Oct 2008
Posts: 42260
Good Answers: 1659
#8
In reply to #6

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 8:55 PM

How thick?

Login to Reply Score 1 for Off Topic
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#10
In reply to #8

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 10:44 PM

What would you estimate the electrostatic field strength at ?

__________________
Break a sweat everyday doing something you enjoy
Login to Reply
Guru
United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4643
Good Answers: 794
#4

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 6:19 PM

Because the fork lift is grounded with straps / chains, most likely the static is in the elevator controls pendant, not the fork lift then. The static charge on the control pendant might be getting created when the elevator control cable rubs on something in the elevator shaft, then is discharging through the operator, to the fork lift, to the ground straps.

__________________
** All I every really wanted to be, was... A LUMBERJACK!.**
Login to Reply
Guru
Hobbies - DIY Welding - New Member

Join Date: Apr 2008
Location: Bristol, Tennessee
Posts: 1158
Good Answers: 57
#5

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 7:00 PM

I think there are devices, old and new, that can show which way the charge is going. Maybe the fork lifts aren't properly discharging through the epoxy. If a person walks up and touches the pendant and gets zapped, there's your culprit.

__________________
mike k
Login to Reply Score 1 for Good Answer
Guru

Join Date: Jan 2008
Posts: 1753
Good Answers: 59
#11

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 10:53 PM

Epoxies are excellent insulators. The triboelectric effect between them and rubber is also excellent. To accentuate your problem, that is.

You may have to upregulate humidity, that may be difficult. Or install ion generators, the type downregulates all kind of static electricity for static sensitive electronic assembly stations. It is standard for them.

Login to Reply
2
Guru
Australia - Member - New Member

Join Date: Feb 2008
Location: Australia
Posts: 2111
Good Answers: 249
#12

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/17/2013 11:25 PM

The background assumption of static is a good first option and should be fully explored, however there may be another explaination.

Just like you can get zapped getting in and out of a car (even when the car is grounded) the operator cold also get zapped. If they are wearing insulating shoes (sneakers/joggers) and synthetic clothing, then merely the action of moving on a vinyl covered seat could charge them individually. (Your description rules this out as you describe the roll cages also sparking.)

I suspect that even with the usual grounding attempts of chains/wire/conductive rubber that the epoxy floor is the insulating medium and thus the operator and forklift accumulate static until reaching a discharge point. (The lift pendant)

"Step potential" might also be involved but significantly less likely. The mounting point for the pendant might be at a different insulated potential to the floor that the forklifts (and operators) are grounded to providing an apparent static shock. The movement of one set of wheels onto the lift platform might bring another static potetnial into play relative to the pendant and the normal floor.

__________________
Just an Engineer from the land down under.
Login to Reply Good Answer (Score 2)
Guru
Hobbies - DIY Welding - New Member

Join Date: Apr 2008
Location: Bristol, Tennessee
Posts: 1158
Good Answers: 57
#13

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 1:34 AM

My car zaps me when I get out of it. How about changing the trigger for the lift, maybe a rubber hose on the floor, like the bell ringer from the old gas stations, for old tech, or a high tech proximity switch or an optical switch the operator waves his hand through. Take the static problem out of the picture.

My sister tells me to put a safety pin on the cuff of my pants to ground me to keep the car from zapping me. I'll have to try that!

__________________
mike k
Login to Reply
Guru
Australia - Member - New Member

Join Date: Feb 2008
Location: Australia
Posts: 2111
Good Answers: 249
#14
In reply to #13

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 2:08 AM

The secret to not getting zapped when getting out of a car is very simple and failsafe.

The static is usually from your pants rubbing on the seat as you rotate to leave the car, then placing your insulated feet on the ground and then reaching to the door to close it.

The solution is to ALWAYS grab the door frame before touching the ground. This brings you and the car body to the same potential and then when your feet touch the ground the static is discharged from the surface of your shoes (You don't feel a thing).

Spent 26 years in automotive industry. It's absolutely worst thing with brand new cars as they roll off the line and you drive them to the storage/shipping lots.

I also had troubles with carpet floors and my shoulder zapping the steel cover strips on external corners of sheetrock walls.

On the up side, I printed my thesis at Uni using static from the carpet floor to trigger the coin slot detection in the copiers.

__________________
Just an Engineer from the land down under.
Login to Reply Off Topic (Score 5)
Power-User

Join Date: May 2009
Location: CORDOBA ARGENTINA
Posts: 157
Good Answers: 4
#15
In reply to #13

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 2:31 AM

Just guessing , I have no idea about your plant layout.

Locate a mobile grounded metal brush on a flexible lever, near the elevator door, as the car goes near it , it will discharge.

Maybe to touch it by the car, bottom or both side .

Or a grounded metal strip at the floor , and a conductive rubber in the car.

You can locate the strip , under a thin epoxi cover , so the carĀ“s braking will not move it , and make a good foundation to the concrete floor.

Is corrosion is a fact , use Stain less steel. AISI 416 or any suited to your invorement.

The same rubber conducting strip used on family cars.

__________________
devitg
Login to Reply Score 1 for Good Answer
Guru

Join Date: Mar 2011
Location: Sebastopol, California
Posts: 1037
Good Answers: 47
#16
In reply to #13

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 2:37 AM

Rub a dryer sheet on the seat of the car. Fabric softener is a great anti static material and a dryer sheet is very available. I have used them in the office to help keep from zapping the computers. Modern fabric chairs and clothing create big voltages and fabric softener keeps them from doing so.

__________________
Most people are mostly good most of the time.
Login to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16497
Good Answers: 661
#17

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 2:55 AM

The operators say they only get zapped at the elevator (pendants and wall panel controls)
Surely it's easy enought to ground the wall panel control (or check it is grounded).
Everyone seems to be missing that it could be the operators who are building up the static charge rather than the equipment?
Or am I too far out of the box?

Del

__________________
health warning: These posts may contain traces of nut.
Login to Reply Score 1 for Good Answer
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 29966
Good Answers: 809
#19
In reply to #17

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 3:16 AM

Why has that box got two phono plug connections?

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Login to Reply Off Topic (Score 5)
Guru

Join Date: Mar 2007
Location: Etherville
Posts: 12331
Good Answers: 115
#20
In reply to #19

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 3:42 AM

More interesting, is it AC or DC ? In my experience AC works better for cats (it's just the hilarity factor of watching them jump up and down). At a rough guess, that 5V - not nearly enough

__________________
For sale - Signature space. Apply on self addressed postcard..
Login to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16497
Good Answers: 661
#22
In reply to #19

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 3:57 AM

Stereo...
Del
(IBE... in box entertainment)

__________________
health warning: These posts may contain traces of nut.
Login to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Netherlands - Member - New Member Fans of Old Computers - Commodore 64 - New Member

Join Date: Sep 2007
Location: Japan
Posts: 2703
Good Answers: 38
#23
In reply to #22

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 4:11 AM

Or is it a Catstatic Battery?

__________________
From the Movie "The Big Lebowski" Don't pee on the carpet man!
Login to Reply Off Topic (Score 5)
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 29966
Good Answers: 809
#25
In reply to #22

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 5:42 AM

So long as it's not a cat's whisker radio connection, that's OK.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Login to Reply Off Topic (Score 5)
Guru

Join Date: Mar 2007
Location: Etherville
Posts: 12331
Good Answers: 115
#26
In reply to #25

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 6:56 AM

I thought it too funny (threre but for the grace......). Sorry, but nobody so far has got the gag. All said, some most excellent comments, I can't but help chuckle when I see a fuuny. My own fox pas are may more

__________________
For sale - Signature space. Apply on self addressed postcard..
Login to Reply Off Topic (Score 5)
Guru

Join Date: Dec 2005
Location: Wisconsin USA
Posts: 837
Good Answers: 37
#18

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 3:11 AM

As already noted, epoxies are generally very good insulators. This means that your dragging chain has no ground to discharge into. Static-dissipating floor coverings are available; any supplier of industrial floor coatings should be aware of them, and able to supply them. Even if you only repaint the area where the forklifts are when the operator reaches for the pendant - and provide a ground that makes contact with the paint patch - the problem should go away. I worked in a facility building medical electronics, and every floor covering in our building was made to dissipate static charges.

Just for grins: could you spray the pendant cord with anti-static fabric spray, all the way up to where grounded metal is part of its support? You might even run a bare copper wire down alongside the pendant cord, grounded up top, and making contact with the fabric spray for most of the length. End the bare wire above the operator's reach, and sheath it with, say, electrical tape for a foot or two above that point.

__________________
" Ignorance and arrogance have more in common than their last four letters. "
Login to Reply Score 1 for Good Answer
Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 5049
Good Answers: 272
#24
In reply to #18

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 4:44 AM

Even if you only repaint the area where the forklifts are when the operator reaches for the pendant

GA

To try out this solution tape a piece of grounded aluminium foil to the floor under the point where the grounding straps touch.

__________________
We are alone in the universe, or, we are not. Either way it's incredible... Adapted from R. Buckminster Fuller/Arthur C. Clarke
Login to Reply
Guru

Join Date: Mar 2007
Location: Etherville
Posts: 12331
Good Answers: 115
#21

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 3:49 AM

When you get the answer, I'd like to know so that I can tell my local supermarket. Whenever I use a trolley, rather than a hand-basket, I seem to get zapped if I touch one of the cabinets. Maybe I shouldn't rush thru the place too fast. I did try dragging a length of chain from my tail, but stopped because I was getting funny looks from people.

__________________
For sale - Signature space. Apply on self addressed postcard..
Login to Reply
Guru
Engineering Fields - Electrical Engineering - Hmmm...

Join Date: Jul 2010
Location: Maryland
Posts: 567
Good Answers: 29
#28
In reply to #21

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 7:43 AM

You mean you don't get funny looks from people when you don't drag a chain from your tail?!

Login to Reply Off Topic (Score 5)
Guru

Join Date: Mar 2007
Location: Etherville
Posts: 12331
Good Answers: 115
#31
In reply to #28

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 8:50 AM

Yes, I get funny looks all the time. My current annoyance is lack of avocado in the shops - if I can't get a bacon and avocado sarnie soon, I will go ape.

Many have tried to tug my tail, but few succeeded

__________________
For sale - Signature space. Apply on self addressed postcard..
Login to Reply Off Topic (Score 5)
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#30
In reply to #21

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 7:49 AM
__________________
Break a sweat everyday doing something you enjoy
Login to Reply
2
Guru
United States - Member - Born, raised halfway 'round .....

Join Date: May 2010
Location: Speedway.....
Posts: 1112
Good Answers: 24
#27

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 7:41 AM

Installing and using a remote controller similar to a remote garage door opener to parallel the function of a hanging pendant control! No shock can be felt, it is safe and low cost approach to solve the problem..

Conductive flooring materials as a path for static discharges is very cost prohibitive to install, besides the continued monitoring and maintenance requirements to be effective..

__________________
vsar
Login to Reply Good Answer (Score 2)
Guru
Engineering Fields - Electrical Engineering - Hmmm...

Join Date: Jul 2010
Location: Maryland
Posts: 567
Good Answers: 29
#29

Re: Forklift Operators Get Static Shock at Elevator Pendant.

04/18/2013 7:49 AM

Are you sure it's static? Have you opened the pendant to be sure there are no bare wires inside? the control box as well?

Is the pendant grounded to the control box into which it is connected? Is the control box properly grounded?

Login to Reply
3
Guru
Hobbies - RC Aircraft - New Member

Join Date: Aug 2007
Posts: 830
Good Answers: 9
#32

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/18/2013 9:39 AM

We never had a static problem for 15 years at our plant. Then we did a up grade of the floors, went with a nice pale gray epoxie. It was awesome for keeping the place clean.

But the forklifts were marking it up terribly,

so our forklift leasing company suggested non marking tires, (They are a pale tan color)

It worked, no more black marks, but the end of first day after the swap there wasn't a scale in the plant still functioning!

There were 20 or so small 4 foot square platform scales with load cells, and are constantly weighing skids from the production areas.

The tan tires were not only non marking, but also non conducting I guess no carbon black?

well by the time we discovered what was happening all by accident, a supervisor came up to one of the fork lifts telling them the scale they were headed towards is broke and where to go, when he approached as usual they kinda grabbed the safety cage, and a lightning bolt went through him, he actually got laid out on the floor the voltage was sooo high.

Later testing with a static meter the voltage was several MEGA volts, yes not kilo volts but mega volts.

The cure was a agressive set of rubber and actual copper grounding straps and woven braid copper straps to help drain the static, and even that because of the i guess the epoxie floor diddn't drain the greatest. for if someone would be moving quickly as usual, and weighed something right away they still would kill the scale. it takes a few seconds for it to drain.

so a policy was made to weigh something they had to aproach the scale then stop and count to ten before placing the load on it.

Joe

----

IDLE-TYME

The Original Rolling Ball Clock

http://www.idle-tyme.com

Login to Reply Good Answer (Score 3)
Guru

Join Date: Aug 2012
Posts: 1061
Good Answers: 92
#48
In reply to #32

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/23/2013 12:21 PM

Sounds familiar; packaging powdered products into poly or plastic lined drums in the winter is another scale killer. We just punched in a ground rod and hooked up the scale bases- that way it tends to miss the load cells etc., as long as the connections are kept clean. This can be a big problem in an EX rated location!

Login to Reply
Guru
United States - Member - Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - RC Aircraft - New Member Engineering Fields - Aerospace Engineering - New Member

Join Date: May 2009
Location: Saint Helens, Oregon
Posts: 2213
Good Answers: 69
#49
In reply to #48

Re: Forklift Operators Get Static Shock at Elevator Pendant

08/17/2017 4:05 AM

"This can be a big problem in an EX rated location!"

Neither one one of my "EX's" wasn't very well grounded, one little spark from me and they would explode

__________________
Confucius once said, “ Ability will never catch up with the demand for it".
Login to Reply
Guru
Hobbies - DIY Welding - New Member

Join Date: Apr 2008
Location: Bristol, Tennessee
Posts: 1158
Good Answers: 57
#33

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/18/2013 3:59 PM

At the toll booth for our bridge were metal springy rods that contacted every car and truck passing through. That way the toll collector didn't get zapped when he collected the toll. These could be retro-fitted into the factory floor, with a nice ground rod to insure a good discharge, all in the same installation hole.

__________________
mike k
Login to Reply
Guru

Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#34

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/18/2013 4:20 PM

Install a flat metal bar stock ground plate in front of the elevator that is bonded to the elevator structure and is common attached/bonded to the pendat.

Attach a braided, trailing ground to the forklift body that will contact the ground plate before the lift reaches the stopping location.

Install a metal ground that contacts the forklift operator while they are sitting on the seat.

This will help decrease if not eliminate the buildup.

__________________
They said; "Brain size?" I heard; "Train size?" so I said: "I'll take a small one, thank you."
Login to Reply
Guru

Join Date: Oct 2008
Posts: 42260
Good Answers: 1659
#35

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/18/2013 4:56 PM

I realize that, true to form, the person asking for help neglected to give a location, but, I think that the first response #1, is the simplest, cheapest, easiest thing to try.

If that doesn't work, there's a short somewhere and it will have to be lengthened.

Login to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16497
Good Answers: 661
#37
In reply to #35

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 2:44 AM

Yup, pissing on the floor is cheap...
Del

__________________
health warning: These posts may contain traces of nut.
Login to Reply
Guru

Join Date: Oct 2008
Posts: 42260
Good Answers: 1659
#44
In reply to #37

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 10:38 AM

And saves operators the bother of walking to the bathroom.

Login to Reply
Guru

Join Date: Dec 2005
Location: Wisconsin USA
Posts: 837
Good Answers: 37
#38
In reply to #35

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 3:07 AM

The original post contains an indication that this is NOT the answer: "The operators say they only get zapped at the elevator (pendants and wall panel controls) and not at other pendants like roll up doors." It seem highly improbable that the relative humidity differs so drastically from point-to-point in the plant that some pendants are always OK, and specific other ones are not . . .Even if some weather conditions or other factors influenced the RH values, it's hard to see how one area would CONSISTENTLY be so low as to provoke discharges,and all of the other areas would always have higher RH, so much different that static discharges never occur.

To me, that suggests that there's a difference in the conductivity of the floor in those areas just in front of the elevator on both floors.

__________________
" Ignorance and arrogance have more in common than their last four letters. "
Login to Reply
Associate

Join Date: Apr 2009
Posts: 36
#40
In reply to #38

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 6:58 AM

Our plant is in southeastern Ohio.

There is only one climate controlled room with low humidity and it is not near the elevator, nor does this room have a problem with static electricity.

We do try to keep the plant between 70 and 74 deg F. year round.

Login to Reply
Guru
United States - Member - Born, raised halfway 'round .....

Join Date: May 2010
Location: Speedway.....
Posts: 1112
Good Answers: 24
#42
In reply to #38

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 9:12 AM

It is possible that difference in floor conductivity may be what is causing the static shock problem.. But to correct that by installing Conductive flooring materials onto the immediate area of the elevator, as a static discharge path is going to be a very cost prohibitive. Beside the initial installation costs, there is also the added costs for the continued monitoring and maintenance requirements, just to ensure effectiveness of such solution..

__________________
vsar
Login to Reply
Guru

Join Date: Dec 2005
Location: Wisconsin USA
Posts: 837
Good Answers: 37
#43
In reply to #42

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 10:31 AM

"Instal" (conductive flooring) = "paint, and run a wire in a very shallow groove off to a decent ground." Think: one man, half a day, 1 gallon of paint. "Maintain, monitor" = the operators will tell you if it starts happening again. Someone suggested taping down a sheet of aluminum foil, grounded, to test; that ought to be even quicker - and the plant could leave one level as-is, for direct comparison testing, maybe get fancy and reverse which is grounded and which not, for higher confidence factor. We're talking what, $10 in materials? And the ground wire could be used again elsewhere. or left in place for the floor painting. For permanent installation, run a Skilsaw (r) across the space, with a carbide blade set 1/16th inch deep for grooving. Or wait & do it next time that the floor needs re-coating, and use a ribbon conductor.

I'd give you static about projecting your idea of what is cost-prohibitive onto troyalec, but I'm feeling mellow, so, no charge.

__________________
" Ignorance and arrogance have more in common than their last four letters. "
Login to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#36

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/18/2013 7:26 PM

You could outfit your drivers with these snazzy static eliminator watches...

__________________
Break a sweat everyday doing something you enjoy
Login to Reply
Commentator

Join Date: Dec 2006
Posts: 64
Good Answers: 3
#41

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/19/2013 8:48 AM

Until you find the source can you install a call chain from the pendant to a location where it would drag on the tow motors charge and equalize any charge? I don't know if sparks are allowed in the area but if everything is at the same voltage at least the operators will stop that funny twitch they developed.

On the other hand if the tow-motors are insulated from the floor you may be building a motorized version of a Kelvin Water Drop generator and charging the tow-motors up to a very high voltage. That in its self would be pretty interesting to try, if the operators hair starts to stick straight out you maybe on track to reducing your electric bill. Let me know if that works.

I tried some "static" testing with my cat and a balloon. I can get the balloon to stick to the wall but the cat keeps falling off. Hey Del do I need a long hair cat for this test?

Login to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 29967
Good Answers: 1671
#45
In reply to #41

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/20/2013 7:50 AM

Not necessarily....

__________________
Break a sweat everyday doing something you enjoy
Login to Reply
Commentator

Join Date: Dec 2009
Location: Coffeyville, KS
Posts: 59
#46
In reply to #45

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/22/2013 1:05 PM

Will some member of ASPCA please sharpen this cat's claws?

__________________
Regards, Pete Olsen
Login to Reply
Guru
Australia - Member - New Member

Join Date: Feb 2008
Location: Australia
Posts: 2111
Good Answers: 249
#47

Re: Forklift Operators Get Static Shock at Elevator Pendant

04/22/2013 5:35 PM

If it is the insulating floor, then there are "dissipative" cleaning materials that can be used without modification of the floor. They are used in electronics manufacturing facilities and the like since they don't want insulating wax layers on the floors.

Look up ESD protective surfaces and you will find the cleaning products necessary. They are not expensive and they do work.

If you want to get scientific about it there are ways to test the dissipative properties of the floor to confirm your diagnosis.

By the way, the earlier picture of the cat with styrene attachments would have made a good "caption this" with answers like "preparing for climate change, this cat has increased insulation properties" and so on.

__________________
Just an Engineer from the land down under.
Login to Reply Score 1 for Good Answer
Login to Reply 49 comments
Interested in this discussion?
You can "subscribe" to this discussion to be notified of new comments.
Click on the Subscribe menu at the top of the page.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Deefburger (1); Del the cat (3); devitg (1); dj95401 (1); dvmdsc (2); Epke (2); JNB (1); JRaef (1); Just an Engineer (3); Kris (4); leveles (1); Lo_Volt (2); lyn (4); mike k (3); NSS (1); peteolsen (1); PWSlack (3); Randall (1); Ron (3); SHOCKHISCAN (1); SolarEagle (6); TommyTech (1); troyalec (1); vsar (2)

Previous in Forum: Reliability   Next in Forum: Secondary Y-ph Earthing of Potential Transformer

Advertisement