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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Lyle Williams on April 06, 2018, 05:37:43 pm

Title: Loss of service neutral
Post by: Lyle Williams on April 06, 2018, 05:37:43 pm
In Australia we had a tragic electrical incident (3000km from me, no personal involvement) where the victim survived but it likely to remain in a vegitative state.

She was shocked touching an outside garden tap.  Investigations have identified loss of the service neutral as a significant factor.  The reasons for the absence of a functioning neutral are still ongoing.

It appears that the return path to the power company's transformer became via the earth, making all bonded metalwork in the house live in the process.

It is informative to draw up a circuit diagram of this incident to understand what the impact of a lost neutral can be.
Title: Re: Loss of service neutral
Post by: Jean-Pierre Coetzee on April 08, 2018, 11:59:35 am
In Australia we had a tragic electrical incident (3000km from me, no personal involvement) where the victim survived but it likely to remain in a vegitative state.

She was shocked touching an outside garden tap.  Investigations have identified loss of the service neutral as a significant factor.  The reasons for the absence of a functioning neutral are still ongoing.

It appears that the return path to the power company's transformer became via the earth, making all bonded metalwork in the house live in the process.

It is informative to draw up a circuit diagram of this incident to understand what the impact of a lost neutral can be.

I have to question why is is still possible for such a problem to exist in this world, I can understand that some things have to be grandfathered but some things should really just be made illegal and be forced to be replaced.
Title: Re: Loss of service neutral
Post by: John Roberts {JR} on April 08, 2018, 02:18:11 pm
I have to question why is is still possible for such a problem to exist in this world, I can understand that some things have to be grandfathered but some things should really just be made illegal and be forced to be replaced.
I expect it is already illegal and will now be corrected.

Stuff happens.

JR
Title: Re: Loss of service neutral
Post by: Daniel Levi on April 08, 2018, 03:10:14 pm
Could the neutral return via earth be intentional as part of a Single Wire Earth Return system and something else has come amiss.

See: https://en.wikipedia.org/wiki/Single-wire_earth_return

Tragic nonetheless and something that might take a while to properly figure out what happened.
Title: Re: Loss of service neutral
Post by: Jonathan Johnson on April 08, 2018, 10:49:46 pm
Could the neutral return via earth be intentional as part of a Single Wire Earth Return system and something else has come amiss.

See: https://en.wikipedia.org/wiki/Single-wire_earth_return

Tragic nonetheless and something that might take a while to properly figure out what happened.

My wild guess is the home may have been grounded/earthed via the cold water pipe rather than a separate grounding electrode, and then somewhere along the line the cold water line to the house was replaced with plastic, rendering the grounding ineffective.

When the neutral failed, this energized the pipes in the house. The victim touched the energized tap, completing the circuit to ground.

Again, that's wild speculation based on real life possibilities.
Title: Re: Loss of service neutral
Post by: Stephen Swaffer on April 09, 2018, 02:50:33 am
The type of grounding electrode is irrelevant in this case-there are many code compliant ground electrodes that would have allowed this to happen.  In fact, a metallic water or even gas connection shared with another home could have created issues in a second home.  I was asked to upgrade a service in a home that had a near miss with a fire-15 amp breaker on a #14 wire almost caught fire.  The breaker was fine.  The problem turned out to be a bad neutral- the home was getting its neutral through the #14 to the furnace then through the gas line to other surrounding homes.  All required grounding electrodes existed and were in good repair.

Normally, there will be warning signs. Lights dimming, or especially getting brighter ( though with new LEDs this probably won't be noticeable).