ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 ... 9   Go Down

Author Topic: How many mA in an Ampere?  (Read 23649 times)

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3361
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
How many mA in an Ampere?
« on: April 02, 2016, 06:22:07 PM »

I presented a No~Shock~Zone seminar last night at the music school where I teach, and had one 50+ year old electrician claim that 120-volts wouldn't kill anyone since he's been shocked lots of times. When I told him that 30 mA was enough current to cause your heart to go into fibrillation, he said that since there was a 20 amp circuit breaker on the outlet there was nothing to worry about. It took me a minute to figure out he really didn't understand the difference between mA (milli-amperes) and Amperes. Guess I need to add a slide to the presentation explaining how 1,000 mA equals 1 ampere of current. Perhaps the problem is that electricians are used to working in Amps, while I'm describing mA fault currents for electrocutions. I'm also thinking about creating a slide showing a human body with 1,000 ohm resistance in a shock situation with an ohm's law chart. Oh, maybe I need a slide describing what "electrocution" actually is. Back to basics, I guess.

This is also why I like to do live seminars rather than just writing about stuff. Sometimes I assume my readership knows more than they actually do. What other electricity basics do I need to include in a N~S~Z seminar?
« Last Edit: April 02, 2016, 06:32:56 PM by Mike Sokol »
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

David Buckley

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 565
Re: How many mA in an Ampere?
« Reply #1 on: April 02, 2016, 07:19:08 PM »

I keep hearing people say "consult a qualified electrician", but man, are you rolling the dice doing that....
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3361
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: How many mA in an Ampere?
« Reply #2 on: April 02, 2016, 07:27:39 PM »

I keep hearing people say "consult a qualified electrician", but man, are you rolling the dice doing that....

We say that for legal reasons, but this guy last night was indeed a "qualified" electrician. I'm sure he can wire up anything to code, but like nearly every other electrician I've worked with, he really didn't seem to understand Ohm's law and how it applies to troubleshooting. Plus he keep insisting that 120-volts can't kill anyone. Why does the public assume that a 120-volt shock is safe?

So how do I simplify Ohm's law sufficiently that the public can understand it? This is a tricky problem.
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6481
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: How many mA in an Ampere?
« Reply #3 on: April 02, 2016, 07:40:16 PM »

I presented a No~Shock~Zone seminar last night at the music school where I teach, and had one 50+ year old electrician claim that 120-volts wouldn't kill anyone since he's been shocked lots of times. When I told him that 30 mA was enough current to cause your heart to go into fibrillation, he said that since there was a 20 amp circuit breaker on the outlet there was nothing to worry about. It took me a minute to figure out he really didn't understand the difference between mA (milli-amperes) and Amperes. Guess I need to add a slide to the presentation explaining how 1,000 mA equals 1 ampere of current. Perhaps the problem is that electricians are used to working in Amps, while I'm describing mA fault currents for electrocutions. I'm also thinking about creating a slide showing a human body with 1,000 ohm resistance in a shock situation with an ohm's law chart. Oh, maybe I need a slide describing what "electrocution" actually is. Back to basics, I guess.

This is also why I like to do live seminars rather than just writing about stuff. Sometimes I assume my readership knows more than they actually do. What other electricity basics do I need to include in a N~S~Z seminar?

I think a video with a bench power supply showing would be more tangible.  As I type this the though of hurting lab animals for this purpose seems cruel.  Stupid human subjects would be better  ::)
Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Len Zenith Jr

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 347
Re: How many mA in an Ampere?
« Reply #4 on: April 02, 2016, 07:52:46 PM »

he said that since there was a 20 amp circuit breaker on the outlet there was nothing to worry about. It took me a minute to figure out he really didn't understand the difference between mA (milli-amperes) and Amperes.

He also doesn't understand that breakers are non brick-wall limiters either.
Logged

Jay Barracato

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2025
  • Solomons, MD
Re: How many mA in an Ampere?
« Reply #5 on: April 02, 2016, 07:55:29 PM »

I worked as an assistant for a guy who would lick a finger and tap a wire to test for hot.

He did it for 30+ years with no problem and then one day caught his heart at exactly the wrong point and knocked him flat on his back.

Sent from my XT1254 using Tapatalk

Logged
Jay Barracato

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3361
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: How many mA in an Ampere?
« Reply #6 on: April 02, 2016, 08:25:58 PM »

I think a video with a bench power supply showing would be more tangible.  As I type this the though of hurting lab animals for this purpose seems cruel.  Stupid human subjects would be better  ::)

I have my custom NSZ demo setup in these seminars, and I could easily do controlled shocks on a volunteer. But I just don't want the liability if something goes wrong. However, that does raise the possibility of creating a video of controlled shocks on a volunteer with medical personnel standing by in case something goes wrong. Flatliners anyone?
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Stephen Swaffer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2514
Re: How many mA in an Ampere?
« Reply #7 on: April 02, 2016, 09:50:15 PM »

Why use volunteers?  Used to have to pay for shock therapy....

Unfortunately, the licensing/training machinery is geared towards getting installations done correctly-a noble goal and one that no doubt saves lives-but that means a lot of card carrying electricians know more about conduit and box fill than in how a control circuit works or how electricity actually behaves.

There was a time when the maintenance department I worked in had one licensed electrician amongst 4 of us-and he literally had no idea how to wire a 3 way switch.  Needless to say, he was worthless (an objective observation) when trying to troubleshoot a machine control.

"So how do I simplify Ohm's law sufficiently that the public can understand it? This is a tricky problem."

Seriously?  E=IR then any 8th grader should be able to convert that to whatever form he needs.

I was taught the m=milli=1/1000 in high school science, so I guess you start by teaching 4 years of high school math and science, THEN start your seminar?

One of the best teachers I ever had had the ability to read his students (class of about 20) and pace his lectures (college level science) in a way that he was confident every student was on board.  But there is only so much you can teach in a few hours of a seminar.
Logged
Steve Swaffer

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6481
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: How many mA in an Ampere?
« Reply #8 on: April 02, 2016, 10:05:59 PM »

I imagine a topic divergence on science education would be a hot button amongst audio professionals.  Mike, you are running into the same issue I have with new hires and just young folks I interact with.  Non existent math skills and an appallingly lack of critical thinking skills.  I have a guy with a four year computer science degree that doesn't understand that just because a device has an rj45 on it doesn't mean it is Ethernet let alone IP capable.  An electrician that doesn't understand electricity?  WTF? 

I passed my ham test in 5th grade and I don't have a super IQ and never excelled academically. 

Like you said a 10 year old even slightly right of the bell curve should be able to solve any term in a simple equation like ohms law.

Sent from my SM-N910V using Tapatalk

Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Frank DeWitt

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1010
    • LBP DI Box
Re: How many mA in an Ampere?
« Reply #9 on: April 02, 2016, 10:08:53 PM »

I have always been surprised that most electricians are all about the code and neat workmanship but know very little about basic electricity.  I thought there would be some curiosity there.  Mechanics seem to know and even care about how cars and other machinery work, you even here things like she's hurting, or Ouch, shut it off it is hurting it self. Not so with most electricians.  I don't know why.
Logged
Not to Code

ProSoundWeb Community

Re: How many mA in an Ampere?
« Reply #9 on: April 02, 2016, 10:08:53 PM »


Pages: [1] 2 3 ... 9   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.038 seconds with 20 queries.