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#127157 05/10/01 05:22 PM
A
Anonymous
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Quote
L1 & L2 both to ground would be a 'ground fault'
Still might not be detected...

Quote
a human holding both L1 & L2 ... would be a 'short'
If my twin brother who has the same impedence as I were holding L1 while I held L2 standing on the ground in bare feet...

Quote
"The GFCI will not protect a person against a line to line shock"
makes the noodle look important !
A GFCI won't protect against line to neutral either (120 or 240 V). What the listing doesn't mention is that it may also fail to detect symmetrical (240 V) line to ground faults.

A 120 V GFCI still may trip when a human hand shorts line to neutral while standing on the basement floor, touching the sink, etc.

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#127158 05/10/01 08:40 PM
Joined: Oct 2000
Posts: 5,392
S
Member
those instructions are simply stating that the device lives only up to it's name.
[Linked Image]
i would wager that a perfect short across L1 & L2 , or perfect 'symetrical ground fault' from both to Grn that would leave a device set to trip @ 50ma untripped , while climbing into many 00000's of Amps would be hard even in a laboratory setting to create.
[Linked Image]

#127159 05/10/01 08:42 PM
Joined: Oct 2000
Posts: 5,392
S
Member
shall we continue into 3ph GFI's ????

[Linked Image]

#127160 05/10/01 09:14 PM
A
Anonymous
Unregistered
Quote
i would wager that a perfect short across L1 & L2 , or perfect 'symetrical ground fault' from both to Grn that would leave a device set to trip @ 50ma untripped, while climbing into many 00000's of Amps would be hard even in a laboratory setting to create.
Whoa!
An L1 to L2 short no matter how perfect or imperfect will not (almost never) trigger the GFCI, low impedance, high impedance, arcing, or whatever.

I could recreate this is my backyard (but preferably yours) any dry day.


As for the symmetrical ground fault, I could do it in a lab with two closely matched power resistors. I would guess that I could do it with two christmas light bulbs and two three-way switches with their handles tied.

But it is a pointless experiment to me since Scott can do it for me in his head.


[This message has been edited by Dspark (edited 05-10-2001).]

#127161 05/10/01 09:22 PM
A
Anonymous
Unregistered
On the matter of three equal phases, that case has just a few combinations more than two-pole, but still the same issues.

Symmetrical ground faults and line-to-line and line-to-neutral faults won't be detected by the GFCI.

#127162 05/11/01 02:53 AM
Joined: Oct 2000
Posts: 2,723
Likes: 1
Broom Pusher and
Member
Quote
Originally posted by sparky:
Dspark;

from siemens GFI instructions;

"EL GFCI no protege a las personas contra choque de tension entre fases."

[oops.... wrong side....... [Linked Image] ]

.]

Doesn't that look a whole lot scarrier in Spanish?? [Linked Image]

Apparently, the GFCI is not going to protect anyone with tense faces [joke [Linked Image]].

I've gotta post my "Shock Hazard Sign" in this forum for review. It features a clip art image [cartoon] of a guy getting the Be-Geezes shocked out of him because he placed a finger into a receptacle [on the neutral side too!! so much for accuracy]. It looks so funny, but passes the point well.

On top it has a clipart sign "High Voltage", then some warning messages I made up [this WILL kill you, burn you, destroy you, etc.].

To be funny, I wrote some stuff, similar to the way Warner Brothers' cartoons goof with French words and phrases.

Mine are in Spanish, French and German and not one bit of the text means anything in those languages!!
Many laughs from the signs.

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
#127163 05/12/01 10:06 AM
Joined: Oct 2000
Posts: 5,392
S
Member
well boys;

were back to wondering how to protect a straight 240 piece of equipment here !
[Linked Image]

This thread does leave me wondering about my next installation, as well as inclined to do some experimenting.

I do have a few ornery chickens that just won't stop cra**ing on the porch, maybe they would volunteer ?
[Linked Image]

#127164 05/12/01 02:50 PM
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
Mmmmm... I smell fried chicken!
Extra Crispy Too!

[Linked Image]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
#127165 05/12/01 03:02 PM
Joined: Oct 2000
Posts: 5,392
S
Member
Mr. Webmaster;
I have invited Breaker manufacturers via e-mail to participate here, maybe they'll straighten us out?

better fried chix than fried customers

(they tend to not pay up!)

[Linked Image]

#127166 05/12/01 11:51 PM
A
Anonymous
Unregistered
You protect a straight 240 V piece of equipment by making sure no one can contact the ungrounded conductors. You make sure that everything is bonded so that one conductor can't unintentionally energize one thing while another energizes something else.

With these as givens, the OCPD and GFCI should do the rest.

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