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Need low resistance ESD shoes

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Flyback

Well-Known Member
Hello,
We need ESD shoes for our staff. We need them to make as low resistance as possible from the skin of the foot, to the sole of the shoe.
We don’t want to use footstraps as the staff have to keep taking them on and off as they go outside and back inside etc.
We simply cant find any. Do you know of some?
 

kubeek

Well-Known Member
Most Helpful Member
We simply cant find any. Do you know of some?
You want to tell me that in the whole UK (if you still are there) there is not a single supplier of ESD shoes?
Also, I am not sure what you mean by low resistance. You want the reistance to be fairly high, in the 10Mohm range IIRC, otherwise you are increasing the current that will flow during a discharge endangering the components, and more importantly increasing the risk of electrocution by making a nice low impedance path to ground, basically like standing in a puddle of water.
 

JimB

Super Moderator
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You want the reistance to be fairly high, in the 10Mohm range IIRC, otherwise you are increasing the current that will flow during a discharge endangering the components, and more importantly increasing the risk of electrocution by making a nice low impedance path to ground, basically like standing in a puddle of water.
Correct.

JimB
 

OBW0549

Active Member
You don't want low-resistance shoes; as has already been pointed out, they present a shock hazard-- which is why ESD-protective shoes aren't made that way.

The human body has a capacitance to its surroundings of about 100 picofarads; shoes with 100 megohms of resistance from sole of foot to sole of shoe will discharge that capacitance to ground (assuming the floor is similarly conductive) in barely a hundredth of a second.

Quite fast enough to protect against ESD.
 

ronsimpson

Well-Known Member
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For two years I worked in a factory at sea level, high humidity. We built product with CD40xx CMOS logic. Concrete floors and not ESD protection. No problems.
For the next decades I worked at high altitude, very dry air and the ESD meters say we should have problems. I added humidifiers to bring up the conductivity of air. We grounded all the benches and added wrist straps.
---edited---
We painted the floors with conductive paint.
 

Tony Stewart

Well-Known Member
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In the 80’s I implemented the implemented ESD prevention measures in my former job at Burroughs Unisys. The company subsidized shoes. I got very nice office shoes 1-10M was the criteria from a specialty store. The warehouse concrete was non-poly insulated and tested ol. The factory was double poly-insulated so the concrete was shot-blasted and conductive epoxy was used.
The office carpet could reset expensive computers and disk drives inside a test area surrounded by a grounded cage if you touched the cage. So dissipative spray was used until the carpet was replaced. The FET buffered meter could register from 0 to 200v just from raising one leg off the carpet V=Q/C just from a change in body capacitance to ground and >20kV if we tried hard enough with neoprene soles. Those with sweaty feet in leather soles were ok but not consistent and often too low. I once used foil between sock and sole to make sandles pass as straps were a PITA
 
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Flyback

Well-Known Member
Ref the safety aspect of low resistance esd shoes.......thanks yes, but the resistance through our esd floor is so high that there will be no safety problem if the resistance through the shoe is low....the total resistance through the body->shoe->esd floor tile -> conductive strip beneath esd floor tile -> earth is 70 megohms when an esd footstrap is worn......so even with bare feet (for example), it will be about 69megohms

- - - Updated - - -

however, there are no cheap, low resistance esd shoes.....we woudl accept anything less than 1 megohm.
We are looking for less than £15 per pair of shoes...nothing exists
 
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alec_t

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gophert

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JonSea

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Ref the safety aspect of low resistance esd shoes.......thanks yes, but the resistance through our esd floor is so high that there will be no safety problem if the resistance through the shoe is low....the total resistance through the body->shoe->esd floor tile -> conductive strip beneath esd floor tile -> earth is 70 megohms when an esd footstrap is worn......so even with bare feet (for example), it will be about 69megohms
So when they are wearing their conductive shoes somewhere with conductive floor and get electrocuted, too bad for them?
 

kubeek

Well-Known Member
Most Helpful Member
Ref the safety aspect of low resistance esd shoes.......thanks yes, but the resistance through our esd floor is so high that there will be no safety problem if the resistance through the shoe is low....the total resistance through the body->shoe->esd floor tile -> conductive strip beneath esd floor tile -> earth is 70 megohms when an esd footstrap is worn......so even with bare feet (for example), it will be about 69megohms

- - - Updated - - -

however, there are no cheap, low resistance esd shoes.....we woudl accept anything less than 1 megohm.
We are looking for less than £15 per pair of shoes...nothing exists
Flyback, you really are the quintessential *"asker" on this forum. You allways ask for help with a solution for which you already made your mind, and will not budge nor listen to other ways that others suggest.
earth is 70 megohms when an esd footstrap is worn......so even with bare feet (for example), it will be about 69megohms
Then, why does it matter to you if the resistance of the shoe is 0 ohms or 10Mohms? The difference between 70M and 80M in total resistance to ground is about 10%, so I just don´t comprehend where you see ANY practical difference, and why you want to avoid industry-standard shoes.
(and all the other suggested standard approaches to whatever problems over the oh so many years)

So please, would you this time spare the usual like, and instead give me an actual reply that addresses my point(s)?
 
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gophert

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So when they are wearing their conductive shoes somewhere with conductive floor and get electrocuted, too bad for them?
In this era of google, nobody should be ignorant for more than 30-seconds. If you have the motivation to think someone is stupid, check first to make sure you are just not understanding the topic.

Do you think people who wear electrostatic discharge bracelets are going to get electrocuted? How many floors are energized? What is the conductivity of an ESD shoe? What is the capacitance of a typical high voltage buildup that causes static damage?

To answer your question, no, Nobody has been electrocuted from wearing ESD shoes. Note the OPs comment about 1M ohm typical discharge path. Note, they are very common in electronic assembly, flammable solvent handling areas (to avoid static sparks), even in dust-free areas because you don't want to attract lint through static cling.

<Mod edit: Removed insulting comment - Matt>
 
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ronsimpson

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In this era of google, nobody should be ignorant for more than 30-seconds.
What an ignorant thing to say. ;) Just kidding ..... maybe

In this era there are people that seem to choose to be ignorant.
In the era there are people that sale ignorance by the case and others that stand in line to pay for it.
 

gophert

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In the era there are people that sale ignorance by the case and others that stand in line to pay for it.
...And you found the raw nerve that motivated my post.
 

JonSea

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In this era of google, nobody should be ignorant for more than 30-seconds. If you have the motivation to think someone is stupid, check first to make sure you are just not understanding the topic.

Do you think people who wear electrostatic discharge bracelets are going to get electrocuted? How many floors are energized? What is the conductivity of an ESD shoe? What is the capacitance of a typical high voltage buildup that causes static damage?
Hello,

......We need them to make as low resistance as possible from the skin of the foot, to the sole of the shoe.....
Flyback stated he wanted the absolute minimum resistance from sole to shoe to floor, and implied that existing solutions were unacceptable. Then he stated that low resistance (i.e., much lower than existing ESD solutions and ideally zero) wouldn't be a safety risk because the floor had high resistance.

<Mod edit: Removed unnecessary comments - Matt>
 
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JonSea

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In this era of google, nobody should be ignorant for more than 30-seconds. If you have the motivation to think someone is stupid, check first to make sure you are just not understanding the topic.
Wonderful advice Gophert. You might try reading and understanding all the posts in a topic before lamely attempting to school somebody else.
 

gophert

Well-Known Member
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we woudl accept anything less than 1 megohm.
Flyback stated he wanted the absolute minimum resistance from sole to shoe to floor, and implied that existing solutions were unacceptable. Then he stated that low resistance (i.e., much lower than existing ESD solutions and ideally zero)
I must have missed that "ideally zero" phrase. Oh wait, I didn't miss it from the OP, only you assumed zero. "Low" is a relative reference. It looks like 1M or less was "low" by the OPs terms.
 

JonSea

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It seems that posts 3, 4 and 6 came to the same conclusion I did regarding the OP's question. I seem to be in good company.

<Mod edit: Removed unnecessary comments - Matt>
 
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