RE: Likely a common mistake.

Posted by jea48 (A) on February 20, 2015 at 11:10:06

In Reply to: RE: Likely a common mistake. posted by pc123v on February 18, 2015 at 01:31:54:

This example is for a piece of audio equipment that uses the safety equipment ground.

IF a ground fault event condition were to happen on the fuse switch side of the electrical circuit wiring inside a piece of equipment where the AC power polarity was reversed because of an improperly wired power cord the hot conductor from the wall receptacle will be connected directly to one side of the primary winding of the power transformer of the equipment, two current paths will be provided for the current to flow back to the source the electrical panel. One path, if the power switch is closed, through the neutral conductor. The other path through the safety equipment grounding conductor. If the power switch on the equipment is open the current will only flow through the safety equipment grounding conductor back to the source. Of course in this instance the ground fault condition would have to be on the load side of the power switch.

With the AC power polarity reversed as described above the safety fuse for the equipment would not blow in the event of a ground fault condition. The fuse would only blow due to an overload condition placed on it from the power transformer's primary winding connected load.

If the 120V AC power circuit is drawn on a piece of paper with the 120V Hot AC conductor connected directly to one side of the primary winding and the other side of the winding connected in series with the on/off power switch and safety fuse, in the event of ground fault condition it is easier see.

120V mains Hot >> one lead of primary winding >> out other lead of primary winding >> power switch >> equipment safety fuse >> neutral Line of mains power. Then you can show possible variation points along the circuit where a ground fault condition connection to metal enclosure, chassis, might happen.

I could give several electrical safety problem scenarios in the event of a ground fault event along the fuse switch circuit path. Though what are the odds of a ground fault event condition ever happening inside the equipment? Well electrical safety codes and NEMA standards are written because of, what if.
Jim

Charles Hansen comments. (Open in New Window)

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Follow Ups Full Thread

Topic - Ice Age Audio power cords. Check your cords! - cmonfils1@yahoo.com 16:13:20 02/15/15 (27)

Isn't it fun - madisonears 19:35:42 02/20/15 (2)

RE: Isn't it fun - davem1 06:49:16 02/21/15 (1)

Why remove it? Just finished reading a couple of related... - DeKay 20:38:38 03/04/15 (0)

but how do they sound? - panhead 10:45:22 02/18/15 (0)

Likely a common mistake. - Duster 12:44:07 02/17/15 (15)

Great picture illustrations. - jea48 07:45:58 02/20/15 (4)

RE: Great picture illustrations. - Duster 14:39:12 02/22/15 (3)

NEMA 5-15P inlet panel mount plug. - jea48 16:52:44 02/22/15 (2)

RE: NEMA 5-15P inlet panel mount plug. - Duster 17:39:39 02/22/15 (1)

RE: NEMA 5-15P inlet panel mount plug. - jea48 08:59:12 02/23/15 (0)

Neotech and Furutech plugs I was using recently had markings on the inside for Hot/Neutral/Ground. - carcass93 09:26:52 02/19/15 (0)

And a stupid one - madisonears 18:35:22 02/18/15 (2)

RE: And a stupid one - iceageaudio@yahoo.com 12:38:35 02/19/15 (1)

RE: And a stupid one - madisonears 23:31:13 02/19/15 (0)

RE: Likely a common mistake. - pc123v 01:31:54 02/18/15 (2)

RE: Likely a common mistake. - jea48 11:10:06 02/20/15 (0)

RE: Likely a common mistake. - Duster 08:46:16 02/18/15 (0)

Very informative - R Browne 22:29:01 02/17/15 (0)

Good post - Metralla 21:19:32 02/17/15 (1)

RE: Good post - Duster 23:46:16 02/17/15 (0)

RE: Ice Age Audio power cords. Check your cords! - davem1 09:55:31 02/17/15 (0)

"Check" or "Sell"? - Winston Smith 21:32:02 02/16/15 (5)

Pun - Awe-d-o-file 04:02:58 02/17/15 (4)

RE: Pun - Crazy Dave 14:05:39 02/17/15 (1)

RE: Pun - Awe-d-o-file 16:16:35 02/17/15 (0)

Nyuk-nyuk! (Nt.) - Winston Smith 10:32:49 02/17/15 (1)

Well said! n/t - Awe-d-o-file 05:48:12 02/18/15 (0)

Follow Ups

RE: Likely a common mistake. - jea48 11:10:06 02/20/15 (0)

RE: Likely a common mistake.

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