ESD Boot straps

[steved]

Desco, a manufacturer of static control products, says that

The safety of the operator always comes first (before any ESD practices). A 1 megohm resistance to ground is satisfactory for a person subjected to less than 250 VAC. Anything higher than 250 VAC requires special design and safety precautions. If in doubt, always favor the safety of the person when working with live power greater than 250 VAC.

 

[Pullnwire]

Pullinwire,

I work in the industry and our company NEVER requires our contractors to wear lab coats or straps. The straps have a 1 megohm resistor in series.

You walk off the job if they persist. You are NOT in touch with their equipment. If they have onsite engineers, politely ask them to enter the debate. Don't bow down to what they ask for. I have worked a bench time off and on for many years. They have NO right to require this. You and your boss stand your ground and demand the companies engineers take part in this decision.

Why do you wear gloves and boots pullin'????? The dipsquirts in the front office don't have a clue. YOU STAND YOUR GROUND NOW!!!!!!!!!!

76nemo,
Thanks for the input, I just had a conversation with the global director of facilities for this company, and he was not aware of any policy requiring vendors to don any ESD equipment. I think mow it will be between the Pres. of facilities and the manager of production.
Also, I am the boss, so I can walk if I want, but I did 25K in service the last two months. What to do?

 

[Pullnwire]

And that is the way to think about it, wearing EH rated boots dosent change anything about the rules you follow or safety requirements that apply. All it takes is some other part of your body touching anything grounded and the boots ratings are meaningless.

I consider everything hot, the boots are just piece of mind.

 

[ramsy]

If you're asking if I would trust a 1meg resistor to limit shock, the answer is yes. I have an ESD wriststrap.

Thanks for deciphering the bad grammar. Here's some authority on wrist bands.

(f) Conductive articles. When work is performed within reaching distance of exposed energized parts of equipment, the employer shall ensure that each employee removes or renders nonconductive all exposed conductive articles, such as key or watch chains, rings, or wrist watches or bands, unless such articles do not increase the hazards associated with contact with the energized parts.

6.1.3. Tetrahydrofuran (THF) is extremely flammable and tends to form explosive peroxides. If static electric discharge is a potential problem, use a grounded wrist strap when transferring THF. Fires involving THF are likely to rapidly become fierce; in case of a large fire, sound an alarm and evacuate.

 

[iwire]

Also, I am the boss, so I can walk if I want, but I did 25K in service the last two months. What to do?

So what exactly are you doing that you or your men are constantly exposed to electrical hazards?

When I am ruining pipe and wire, hanging and wiring fixtures etc I should not be exposed to any electrical hazards.

And if you are doing live work beyond what OSHA allows the problem seems to be on your end not the customers.

 

[ramsy]

Desco, a manufacturer of static control products, says that A 1 megohm resistance to ground is satisfactory for a person subjected to less than 250 VAC.

Regardless of Mfg. endorsement, if employers require this device as condition of employment, it appears some can get away with it regardless of resulting fatalities.

29 CFR Parts 1904 and 1952
VI. Legal Authority
C. The Final Recordkeeping Rule's Key Provisions Are Reasonably Related to the Purposes of the OSH Act

1. Exemptions From Recordkeeping Requirements

The final rule contains two categories of exemptions that, together, relieve most employers of the obligation routinely to record injuries and illnesses sustained by their employees. Section 1904.1 contains a "very small-employer" exemption: Employers need not record injuries or illnesses in the current year if they had 10 or fewer employees at all times during the previous year, unless required to do so pursuant to Sections 1904.41 or 1904.42. Section 1904.2 contains a "low-hazard industry" exemption: Individual business establishments are not required to keep records if they are classified in specific low-hazard retail, service, finance, insurance, or real estate industries.

a. The size-based exemption. Section 8(d) of the Act expresses Congress' intent to minimize, where feasible, the burden of recordkeeping requirements on employers, particularly small businesses: "Any information obtained by the Secretary, the Secretary of [HHS], or a State agency under this Act shall be obtained with a minimum burden upon employers, especially those operating small businesses.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=16312

Since, US Disability ratings pay much higher compensations for longer periods, than do workers compensation insurance, perhaps its best to arrange an injury contingency between co-workers; to place each other's injured bodies in the gutter (public property) just beyond employer's (private) property.

 

[iwire]

Thanks for deciphering the bad grammar. Here's some authority on wrist bands.

(f) Conductive articles. When work is performed within reaching distance of exposed energized parts of equipment, the employer shall ensure that each employee removes or renders nonconductive all exposed conductive articles, such as key or watch chains, rings, or wrist watches or bands, unless such articles do not increase the hazards associated with contact with the energized parts.

It would be an OSHA violation to be within reaching distance of exposed energized parts without a good reason and all the proper PPE.

In other words, when it's time to put on the PPE it would be time to remove any static straps.

 

[ramsy]

when it's time to put on the PPE it would be time to remove any static straps.

Yes, the "Put me in the gutter" contingency plan would only be needed when we were in hurry or otherwise forgot to remove the static straps.

Happy Thanksgiving Bob
Time to eat some Turkey.

 

[dbuckley]

Have any of you chaps ever used a neon screwdriver to test a circuit? Thats you connected to the hot by way of a resistor, and the value is usually a lot lower than a ESD strap has.

 

[big john]

Yes, the "Put me in the gutter" contingency plan would only be needed when we were in hurry or otherwise forgot to remove the static straps....

I hear your concern, but unless you're in too much of a hurry to put on rubber-gloves and outers it shouldn't matter how conductive the rest of you might be....

I work in an industry that requires a lot of "stupid" rules, too. I'm slowly learning to pick my battles.

-John

 

[76nemo]

Alrighty then.

Alrighty then.

Bob, I truly see your point. I think mine may have been missed.

#1. I was referring to online work, not construction.

#2. Even if you were doing construction 25' up in the air on a scissor lift on rubber wheels,...what is a lab coat and foot straps going to guard?

 

[Pullnwire]

So what exactly are you doing that you or your men are constantly exposed to electrical hazards?

When I am ruining pipe and wire, hanging and wiring fixtures etc I should not be exposed to any electrical hazards.

And if you are doing live work beyond what OSHA allows the problem seems to be on your end not the customers.

I take the appropriate precautions for the job at hand. This is a service client, I do everything from change lightbulbs to install new panels for new equipment. I dont want to worry about the metallic fabric strap tucked into my sock while I am changing a broken outlet or a bad ballast over a workbench.

 

[Pullnwire]

Problem resolved.

Problem resolved.

as of today, I received a call from the director of facilities for my client and was told that under no circumstances were we to wear any ESD protective equipment unless I was in contact with any of their product or any equipment with product on it. That is a very rare ocasion and I would only need a wrist strap. I am ok with that.

 

[zog]

as of today, I received a call from the director of facilities for my client and was told that under no circumstances were we to wear any ESD protective equipment unless I was in contact with any of their product or any equipment with product on it. That is a very rare ocasion and I would only need a wrist strap. I am ok with that.

Sounds like all you needed to do was ask the right person, I am glad to hear your client looked at the situation with an open mind and made the right decision. Congratulations!

 

[ramsy]

as of today, I received a call from the director of facilities for my client and was told that under no circumstances were we to wear any ESD..

Fortunately, when regulatory bodies are stripped of enforcement mandates or resources, limiting civil law-suit exposure remains a corporate-executive priority.

IMO This decision abates one potential liability, unless employee's or surviving family proved contractor/employer omitted PPE or LOTO policy.

Has anybody else noticed, with inside-wiring industry notably exempt from public policy, getting PPE or LOTO-negligence cases in court has become more lucrative, and perhaps the last deterrent?

 

[76nemo]

as of today, I received a call from the director of facilities for my client and was told that under no circumstances were we to wear any ESD protective equipment unless I was in contact with any of their product or any equipment with product on it. That is a very rare ocasion and I would only need a wrist strap. I am ok with that.

For once, someone qualified listened to your debate, and your issue was resolved.

I meant what I said,... you stand your ground when someone deems something of that sort pertinent.

 

[McGowdog]

When to use/not use ESD footwear

When to use/not use ESD footwear

This is my first post here and I'm posting my thoughts on ESD as it applies to the appropriate situations here and I'd like to add that I've been eating, breathing, and sleeping ESD (ElectroStatic Discharge) for over 5 years now.

I'm an EET with a Computer area of emphasis and I've been out in the field of Technician and Engineering work for the past 18 years. So now that I think I've qualified myself, I encourage you all to download your free copy of ANSI/ESD S20.20-2007 from the ESD Association if you haven't done so already.

When you're in an EPA (ESD Protected Area), you may be required to wear ESD Protective Devices for the purposes of static control to prevent damage to ESD Sensitive devices, to prevent explosion and subsequent injury and/or loss of life to personnel, etc. But if you're not within 12" of sensitive electronics or not in the EPA to begin with, I see no need for you to don ESD smocks and ESD footwear, especially if you're exposed to high voltage, line AC, etc. The only time ESD footwear is effective, is when you're standing or walking about on an ESD Static Conductive (2.5E4 Ohms to 1.0E6 Ohms or a meg ohm) flooring system or an ESD Static Dissipative (1.0E6 Ohms to 1.0E9 Ohms) flooring system. When you're seated at a bench or ESD work station and will be working on ESDS devices, you need to wear a wrist strap... regardless of the footwear and flooring/matting system. ESD Footwear (ESD shoes, heel grounders, sole grounders, ESD shoe covers, etc.) merely enable you to be mobile and "soft-grounded" as a secondary grounding ESD Technical Element IF the ESD flooring system is being used underneath you. The ESD flooring system also lets us take advantage of mobile carts and chairs (with esd casters or drop chains and seat and seat backs).

Why in the world would you want to waste wearing ESD footwear on non-ESD flooring systems? Why would you have ESD flooring near areas of high voltage or exposed AC Line or where service personnel will be working on such? I wouldn't mess with it. Let me tell you about ESD smocks. I wear cotton shirts and jeans, both made of cotton. With the sweat and salts in my body and on my skin, I am a pretty good conductor and so are my clothes. They work about as well as any ESD smocks. In cleanrooms, they wear smocks for additional reasons; prevention of contamination from personnel to products being isolated from such. I'd be more in tune with using isolated shoes, gloves, etc. and be standing on some form of Switchboard Matting or insulative flooring. Keep in mind, some otherwise NON-ESD shoes may be fairly low resistance or well in the static dissipative range, like Wolverines! I've found them to be less than 3.5E7 Ohms when measures with a Megohmeter in combination with a person.

As we walk around and move around in an EPA, we are static generators. We don't feel anything less than about 3000 volts, but sensitive electronics get damaged at lower and lower voltages and the industry need to reduce this voltage to less than 100 volts regardless of the quote below. It totally disagree with it.

They don't care????? Most of these engineers are DC app geeks. You BEST speak your piece. You aren't in touch with their equipment. Years ago, static protection was an important issue. MOS devices are not nearly as sensitive as they used to be. Your presense is of no concern. You are there working on their electrical system, not products. Most products in this age rarely suffer latent damage. Ask for the onsite engineers on this debate.

This is all wrong. As of about 1995 and during the inclusion of SMT, components have been getting smaller and faster, and thus more prone to ESD damge. If anything, the opposite is true of what's quoted above. TTL may have been tougher and more robust than MOS devices. We also need to take into account damage from Human Body Model, Machine Model, and Charged Device Model. A robotic feeder than installs components generates a lot less voltage but does a lot less damage quicker and dumps more energy quicker than a human being does. We need to leave this discussion to the experts that have taking ESD control serious since before 1975. In otherwords, we'd be arguing with the DoD, NASA, Motorolla, IBM, HP, US Marine Corps, Xerox, Northrop Gruman, Intel, ATT, Delco, RCA, etc. They demand this stuff.

Device types ESD Threshold
GMR Head < 10 volts
MR Head < 20
MOSFETS 10-100
GaAsFET 50-2000
Laser Diodes 70-260
EPROM 100-500
JFET 140-7000
SAW 150-500
OP-AMP 190-2500
256K DRAM 200-300
Schottky Diodes 300-2500
Film Resistors 300-3000
ECL 500-2000
8085 Microprocessors 500-2000

And this has only been since 1997 To put it into perspective, the world spent 85 Billion US dollars on ESD damage in 2004 and the US spent 35-40 Billion alone.

ESD Control and Installation is a profit center. Corporations already build losses into their budgets. The measley money they spend on ESD control only saves them money in material and inventory, labor and re-work costs, facility burden and overhead, warranty support, field and customer service, sales and making customers happy... Wow! I should be in sales. But I'm not. I believe strongly in the field I chose.

Hope that was helpful, allbeit late!

 

[McGowdog]

I would probably comply with the customers request.

I don't know about you guys but I know when I am exposed to electrical hazards. If we are following all the OSHA rules there are very few times we are exposed to electrical hazards anymore than a carpenter, roofer or assembly line worker.

When the time came that I was doing some work that would expose me to electrical hazards I could remove the strap from my foot as I was putting on my other required PPE.

Maybe its just me but regardless of my shoes rating I assume my shoes / sweat / dirt on my feet are conductive at all times.

I don't agree that you should comply to wearing conductive shoes/straps/grounders/ESD Static Conductive (for ordinance, pyrotechnics, flammable or explosive environments) or Static Dissipative (for ESD Sensitive Devices) footwear unless you are in the EPA (ESD Protected Area) AND you are not exposed to AC Line above 250 and/or unless you are in an explosive hazzardous environment AND I would HOPE you aren't exposed the the 250+ AC Line as well.

Could you imagine being in an explosive environment AND being at risk of electrocution? This would be what I'd call Architecture by Satan. Not a good idea from the get-go.

I do like the idea of you not assuming your "NON-ESD shoes" to be insulative. Wolverines, for example, are pretty dissipative. I've seen it with my own eyes. A lot of Static Dissipative shoes on the market don't measure too conductive per ANSI/ESD STM 9.1-2006 Footwear- Resistive Characteristics... as they come in at just below 1.0E9 Ω. But once you get to wearing them with your cotton socks on, your body dumps water and salt into the socks and onto the insoles of the footwear and there's an intentional path between the insole and the outsole; hopefully above 1.0E6 Ω for an SD shoe and hopefully less than 4.5E5 Ω or 450,000 Ω for a Static Conductive shoe. But what about a shoe that has an "unintentional" connection from insole to outsole. Some people out there have a static dissipative shoe and they didn't even know it.

One could step on a combo/footwear tester and see if they fail low, fail high, or pass as a static dissipative shoe (limits depend on the tester, but I'd bet they're set at about 8E5 Ω on the low end and just above or near 3.5E7 Ω on the upper end). Those testers measure a person in combination with the footwear through the stainless steel plate you stand on, your body, and the finger you press the tester with.

To just measure an ESD shoe isn't very practical. It's good to measure a real-world application. What's the resistance seen from personnel through the ESD flooring system to equipment or electrical ground? So when they go and put a 5 lb weight from a megohmmeter in the palm of their hand and the other lead to ground and they're standing on an ESD flooring system, they are going to read less than 3.5E7 Ω to ground; even though the shoe resistance is just less than 1.0E9 Ω. You could almost maybe do this measurement with a Fluke. Flukes don't make good ESD meters because they usually taper off into OL at 3.5 to 4E7 Ω or 40 meg ohms. Most technical elements for ESD are between 2.5E4 Ω and a gig ohm.

You need an EH designated shoe that "provides workers a secondary source of protection from live circuits, wires, or highly charged electrical equipment. The insulating properties of such footwear are measured under dry conditions and may deteriorate in wet environments and with wear."

So, as the quote above says, assume nothing.

I'm for personal safety #1, and I'm from the ESD industry.

 

[McGowdog]

ESD vs AC line protection

ESD vs AC line protection

Add to I'm from the ESD Industry: In my world, personnel are the generators of energy and it's the devices that need protection from us. In your world, it's the machines and power distribution or source of energy that are the generators and it's the personnel that needs protection from it.

I see a need to treat these two worlds separately.

we work at lockeed martin and they make us wear those ESD jackets. i always tell them we cant wear them since they are conductive yet they dont care...

This is another pretty good concern, but it depends. Some are as conductive as 1.0E6 Ω but no more, and some are just less than 1.0E9 Ω. If you wear cotton like I do and sweat like I do, that is about the same as a more conductive smock. What are you wearing that's so insulative? Not cotton, right? Flannel shirts and cotton tees are pretty conductive, especially if we're sweatin' off a few beers from the night before.