ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Southwire Recalls Electrical Outlet Boxes
by Admin - 08/21/19 06:39 PM
Fuse blower plug?
by HotLine1 - 08/20/19 01:50 PM
100 year old Light Bulb
by HotLine1 - 08/20/19 01:26 PM
Forum Updates Coming Soon.
by Admin - 08/18/19 01:55 PM
Anybody Remember this?
by Bill Addiss - 08/17/19 09:07 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 8 guests, and 10 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Portable generator #173992 01/24/08 09:54 PM
Joined: Apr 2007
Posts: 8
J
jem Offline OP
New Member
Customer wants to use a portable generator to power some house circuits. This generator has bonded nuetral/ ground. Since generator is bonded, must I use a transfer switch that switches the nuetral and can the existing ground rod be used for grounding the generator.

2017 / 2014 NEC & Related Books and Study Guides
Re: Portable generator [Re: jem] #173995 01/24/08 10:09 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
Yes, switch the neutral.

No, you don't tie s portable generator to the ground rod.

If he's mounting the generator permanently, it's no longer a portable generator.

My advice? If you're using a portable genny, use extension cords, and portable lights too. Don't even try to tie it in. If you want a stand-by genny, get a real one, and install it properly.

Re: Portable generator [Re: jem] #173996 01/24/08 10:10 PM
Joined: Jul 2007
Posts: 1,335
S
sparkyinak Offline
Member
You should always use a transfer switch. And yes on the ground rod


"Live Awesome!" - Kevin Carosa
Re: Portable generator [Re: renosteinke] #173998 01/24/08 10:28 PM
Joined: Jun 2004
Posts: 202
3
32VAC Offline
Member
Originally Posted by renosteinke


My advice? If you're using a portable genny, use extension cords, and portable lights too. Don't even try to tie it in. If you want a stand-by genny, get a real one, and install it properly.


Agreed. For the generator at home, the extension cords live in a box all marked with where they run to (fridge 1, fridge 2, freezer and lights).

The lights are also in the box (2x 240VAC trouble lights with rough service 250-260V globes fitted). The generator has four outlets fitted for the four main leads with a double adaptor on the end of the lighting lead.

Piece of pie when needed, no hunting around for leads when you need them.

Re: Portable generator [Re: sparkyinak] #174014 01/25/08 04:42 AM
Joined: Jul 2002
Posts: 8,262
Trumpy Offline
Member
Originally Posted by sparkyinak
You should always use a transfer switch. And yes on the ground rod


You never tie a portable generator to a grounding system associated with a house, otherwise you may get circulating earth currents, at the least you may get noise on you radio, at the worst you could kill someone.

A generator is a seperately derived system, it should always be kept away from the mains wiring, unless it is fed in through a transfer switch.

I have to go with what Darren and John are saying, if you only need power when the mains fails and you don't need it instantly, I would go for the labelled flexes and lights, etc.
After all, you can't run a whole house on most "portable" generators anyway.

Re: Portable generator [Re: Trumpy] #174016 01/25/08 06:06 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
Originally Posted by Trumpy
You never tie a portable generator to a grounding system associated with a house, otherwise you may get circulating earth currents, at the least you may get noise on you radio, at the worst you could kill someone.


Mike, under the NEC that really depends on the installation.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Portable generator [Re: iwire] #174020 01/25/08 11:16 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
I think the key word here is "portable."

Some folks think that they are somehow improving things if they bang a ground rod whenever they use a portable, or vehicle mounted, generator. I think we've established that doing so accomplishes nothing ... as the ground rod is essentially irrelevant to clearing faults.

That everything in the building needs to be bonded, and that these paths need to go back to the generator, is another subject. That's why I say "switch the neutral;" there's no way for the electricity to go anywhere else.

Naturally, I assume that the extension cords have intact three-prong plugs!

I don't think I have ever run a wire from a genny, directly to a ground rod. Rather, the transfer switch provided the point where the generator ground was tied into the building's ground system. With a portable genny, this is accomplished by that third prong on the plug.

Re: Portable generator [Re: renosteinke] #174021 01/25/08 11:44 AM
Joined: Jul 2004
Posts: 9,383
G
gfretwell Online Content
Member
I am not sure why they would even bond a truly portable generator. What is the point? A single frame to neutral fault is exactly what you are doing with the bond and two phases faulted to the frame would operate the OC device anyway (HOPEFULLY)
neither is actually a "grounded" conductor. It is arbitrary which one you bond.


Greg Fretwell
Re: Portable generator [Re: gfretwell] #174026 01/25/08 02:15 PM
Joined: Apr 2007
Posts: 8
J
jem Offline OP
New Member
I see portable generators cord connected via a 4 wire cord to a power inlet on a generator panel fairly frequently. What I would like to know is if the portable generator is bonded (internal to the unit) and the neutral is switched at the transfer switch (seperately derived system) a grounding electrode is required. Can a tap be run from the service GEC to accomplish this. If the neutral is not switched (not a seperately derived system), you have a bond at the generator on the load side of the service disconnect when the generator is plugged in.

Re: Portable generator [Re: jem] #174142 01/27/08 03:41 PM
Joined: Jan 2006
Posts: 558
R
Rewired Offline
Member
If the generator has the neutral bonded to "ground" in the generator and a switched neutral is employed in the transfer switch ( as it should be with a bonded generator neutral), a ground electrode should not be used or needed because the neutral is still bonded to ground through the generator.. Doing anything else may cause circulating currents in the grounding / bonding conductors and will defeat the purpose of the switched neutral in the transfer switch.

A.D

Page 1 of 2 1 2

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
The_Lightman
The_Lightman
Orlando, Fl, USA
Posts: 49
Joined: August 2001
Show All Member Profiles 
Top Posters(30 Days)
Admin 21
GeneSF 7
Popular Topics(Views)
257,955 Are you busy
193,682 Re: Forum
183,292 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3