Portable generator

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geochurchi

Senior Member
Location
Concord,NH
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Retired electrician
Hi All, portable generator connected to load by a 3 way switch as a transfer switch, a cord run from the switch connected to the generator for use in an emergency,neutrals all connected together,is this a violation?
Thanks
 

kwired

Electron manager
Location
NE Nebraska
Hi All, portable generator connected to load by a 3 way switch as a transfer switch, a cord run from the switch connected to the generator for use in an emergency,neutrals all connected together,is this a violation?
Thanks
May be a listing issue with the switch. Been several years ago but we once installed some Levition (I think) double throw switches that had a center "off" position. IIRC you couldn't switch from one to the other without stopping at the center position first - you had to relieve pressure on the handle in center position before it would let you switch to the other position. I think this was a switch listed for a purpose like you describe and is what we used it for. (Can't recall if it was single pole or double pole though) I don't think they were anywhere near the price of a spec grade three way switch either.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The typical 3 way switch is listed as a "Snap Switch" and UL says the following in the guide information for Snap Switches (WJQR).
Snap switches have not been investigated for switching a load between two alternate sources of supply.
 

ron

Senior Member
The typical 3 way switch is listed as a "Snap Switch" and UL says the following in the guide information for Snap Switches (WJQR).
Also interesting that the typical 3-way switch may have never been tested with 240V across the terminals (I don't know if they test a typical 3-way at voltages higher than 120 or 150V), which may occur with unsync'd sources.

Although in hindsight - I guess most snap switches can be used on 277V sources, so maybe a non-issue.
 

geochurchi

Senior Member
Location
Concord,NH
Occupation
Retired electrician
Portable generator

Don, interesting point, I had never thought of that fact, my main question was about the bonding of the neutrals.
 

kwired

Electron manager
Location
NE Nebraska
Also interesting that the typical 3-way switch may have never been tested with 240V across the terminals (I don't know if they test a typical 3-way at voltages higher than 120 or 150V), which may occur with unsync'd sources.

Although in hindsight - I guess most snap switches can be used on 277V sources, so maybe a non-issue.
The cheap non spec grade switches that are mostly common in residential applications are usually only 120 volt rated. Most others are rated at least 277 volts.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Don, interesting point, I had never thought of that fact, my main question was about the bonding of the neutrals.

It would depend on how the generator was wired from the factory. If the neutral was bonded in the generator then you would need to switch the neutrals in the transfer switch.

I'm not saying your transfer (3-way) switch is legal or not, just how the neutrals should be handled.
 

jap

Senior Member
Occupation
Electrician
Other than that , I've always felt this type of jury rigging puts the user at the possibility of becoming parallel with the neutral return current if they were to grab ahold of the neutral blade on the male cap when it wasn't plugged into a generator, but I may be overthinking it somewhat.

JAP>
 

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
Other than that , I've always felt this type of jury rigging puts the user at the possibility of becoming parallel with the neutral return current if they were to grab ahold of the neutral blade on the male cap when it wasn't plugged into a generator, but I may be overthinking it somewhat.

JAP>
While you can touch the neutral that is connected to the building system and ground and you would be a parallel path, assuming the building system neutral is not compromised, there is very little voltage available to drive current through you. Not saying it is a good idea, just saying as long as the service and feeder neutrals are ok, it is not a serious hazard.
 

jap

Senior Member
Occupation
Electrician
While you can touch the neutral that is connected to the building system and ground and you would be a parallel path, assuming the building system neutral is not compromised, there is very little voltage available to drive current through you. Not saying it is a good idea, just saying as long as the service and feeder neutrals are ok, it is not a serious hazard.


Just sayin. :)

JAP>
 
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