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#17173 11/22/02 12:41 PM
Joined: Jun 2001
Posts: 12
D
Member
I called Coleman, and they said that I can buy a new end bell assembly that will have a 4 prong twistlock plug and would be compatible with my generator's internal wiring. It would then have a separate neutral and ground.I think that would solve all my wiring woes. Does this ound ok with my setup?

#17174 11/22/02 12:47 PM
Joined: Mar 2002
Posts: 582
R
Ron Offline
Member
The 4 wire plug is a great start. You will need to unbond the n-g in the gen.


Ron
#17175 11/22/02 01:17 PM
Joined: Jul 2002
Posts: 175
E
Member
Why spend money to change the end-bell?

Get a competent electrical contractor (not the one who did the original installation) to hardwire the generator and disconnect the neutral-to-frame bonding jumper.

Because your transfer switch does not switch the neutral conductor, no GEC is required at the generator. Refer to Diagram 1 above.

Ed



[This message has been edited by electric-ed (edited 11-22-2002).]

#17176 11/22/02 02:42 PM
Joined: Jun 2001
Posts: 12
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Member
Ed,
What do you mean when you say hardwire the generator?
The end-bell is about $100 from Coleman.
I would think the electrician's bill would be higher.

#17177 11/22/02 03:21 PM
Joined: Jul 2002
Posts: 175
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Member
By the term "hardwire" I meant to connect the cable directly to the generator terminals without using the receptacle and plug.
Of course, there will be some who will say that this will violate the UL listing, but it will actually be safer.

There is no need for a receptacle in this type of installation, unless you want the generator to remain portable.

It will not be possible to safely use cord connected tools by plugging into the generator receptacle if you disconnect the neutral-to-frame bonding jumper.

Ed

[This message has been edited by electric-ed (edited 11-22-2002).]

#17178 11/22/02 04:30 PM
Joined: Jun 2001
Posts: 12
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Member
okay,
last 2 questions, i swear.
If I buy the new bell housing from Coleman for $100, and I connect that so it has a floating ground (neutral no longer bonded to frame/ground),
1. When I connect the generator to the house with the 4 prong twist lock plugs on each end,do i need to ground the generator to a grounding rod with the external grounding lug or will it be grounded through the house wiring that goes to the transfer switch (6 gauge)?
2. When plugging in tools directly (which we never do), any special considerations (e.g. attach grounding lug to ground rod)?

#17179 11/22/02 06:14 PM
Joined: Jul 2002
Posts: 175
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Member
Dave,
Answers to your two questions, based on circuit principles. There may be NECode rules that take precedence.

1. As I stated above, because the generator winding center-tap (neutral) is solidly connected to the house service grounded (neutral) conductor in your transfer switch(see Diagram 1 above), it is already grounded, and should not be regrounded.

2. Connecting the frame of the generator to a ground rod will not protect you from shock caused by a fault in a power tool!!
Don't plug outdoor tools and appliances directly into the generator receptacles, after it has been modified by "unbonding" the neutral.


The bottom line is - The grounding/bonding requirements for the safe use of a portable generator are different from those for a generator that is wired to a building wiring system.
I recommend that the receptacles in the generator be disabled if it is wired to your building system using a transfer switch. Plug your outdoor tools into the house receptacles which should be GFCI protected.

If you must use the generator receptacles, the system should be wired as shown in Diagram 2 (above) using a three pole transfer switch, and leaving the neutral-to-frame bonding jumper in place.

Ed

[This message has been edited by electric-ed (edited 11-22-2002).]

#17180 11/23/02 12:02 AM
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
Electric-Ed,

If the grounding electrode conductor in diagram two is bonded to both the generator frame (and the generator neutral) as well as the service neutral (at bonding jumper), what is opening the neutral accomplishing?

Would seperate electrodes (and conductors) be better?

(I'm following the blue line representing the EGCs)

It just doesn't seem to be isolating the noodles at all to me...

[Linked Image]

Other than that, I'm glad that I've actually been putting them in right!


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
#17181 11/23/02 12:57 AM
Joined: May 2001
Posts: 552
T
Member
Virgil,
Mine's hooked up like your neighbors(the miner) [Linked Image] [Linked Image]


Donnie
#17182 11/23/02 09:38 AM
Joined: Jul 2002
Posts: 175
E
Member
sparky66wv,

1. Separate systems in the same facility are required to be grounded to the same grounding electrode, or, the grounding electrodes are required to be interconnected.

2. The reason that the transfer switch in Diagram 2 is required to switch the neutral is to prevent the neutral being in parallel with the equipment grounding path (green), when the generator neutral is bonded to the frame, which would create the problem shown in Diagram 3 (above).

3. When the transfer switch breaks the neutral, as in Diagram 2, we have, in effect, two separate systems, only one of which is active at any time.

4. Look at each system individually.
a. Load on utility power (Diagram 4 – this post). Unbalanced load current flows from the load neutral bus (X) back to the source it came from (Z).

[Linked Image from electric-ed.com]

b. Load on generator power (Diagram 5 – this post). Unbalanced load current flows from the load neutral bus (X) back to the source it came from (Y).

[Linked Image from electric-ed.com]

Ed


[This message has been edited by electric-ed (edited 11-23-2002).]

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