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Old 09-21-2012, 07:30 AM   #1
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2-2-4 SEU - Smaller Neutral?


Electrician is installing a 100-amp subpanel approx 80 ft from the 200-amp service panel located at the opposite end of the residence. He is using 2-2-4 SEU wire. Can the neutral wire be smaller gauge than hot conductors?

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Old 09-21-2012, 07:41 AM   #2
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2-2-4 SEU - Smaller Neutral?


I believe SEU only has three conductors including the ground. That is not suitable for a sub panel. You must have four conductors.

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Old 09-21-2012, 07:44 AM   #3
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2-2-4 SEU - Smaller Neutral?


Joe is correct. Type SER with 4 conductors is needed. Also the #2 AL is only good for 90 amps, not 100.
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Last edited by Jim Port; 09-21-2012 at 08:03 AM. Reason: added conductor material
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Old 09-21-2012, 07:57 AM   #4
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2-2-4 SEU - Smaller Neutral?


#2 copper would be fine no? As long as its 75 degree plus rated. Not sure what your ser cables temp rating is.
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Old 09-21-2012, 03:11 PM   #5
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2-2-4 SEU - Smaller Neutral?


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Originally Posted by BRT View Post
Electrician is installing a 100-amp subpanel approx 80 ft from the 200-amp service panel located at the opposite end of the residence. He is using 2-2-4 SEU wire. Can the neutral wire be smaller gauge than hot conductors?
NO WAY a real electrician is doing this. There is so much wrong here it's not funny.
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Old 09-21-2012, 08:05 PM   #6
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2-2-4 SEU - Smaller Neutral?


Thanks for the reply. If you are permitted, can you recommend the size and type of cable for my 100-amp subpanel? I really nervous now because I believe the "electrican" ran the same cable between my house and subpanel in my detached shop.
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Old 09-21-2012, 08:11 PM   #7
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2-2-4 SEU - Smaller Neutral?


It would help to know what edition of the code your area is enforcing. The ampacities have changed.
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Old 09-21-2012, 08:24 PM   #8
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2-2-4 SEU - Smaller Neutral?


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Thanks for the reply. If you are permitted, can you recommend the size and type of cable for my 100-amp subpanel? I really nervous now because I believe the "electrican" ran the same cable between my house and subpanel in my detached shop.
In one post you say opposite end of residence, not you say detached. Did you mean the other end of your property?

It was legal for quite a while to run a 3-wire feeder to a detached structure under certain circumstances. Maybe he is an old timer set in his (unfortunately non-complaint) ways.
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Old 09-22-2012, 08:16 AM   #9
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2-2-4 SEU - Smaller Neutral?


I think the detached was a previous install and the sub panel is new current install.
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Old 09-22-2012, 04:43 PM   #10
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2-2-4 SEU - Smaller Neutral?


I have two independent 200A services in my residence under construction. The services are mounted on the east and west end of house. The west 200A service feeds the 100A subpanel in detached shop. The east 200A service is feeding subpanel mounted next to west 200A service. Why? Electrician put almost the entire house on west service panel rather than split load and breakers. I have no spare breaker space in the west service panel, the east service panel is empty except for six 20A breaker. So his solution for creating addition breaker space on west end of house is mounting a 100A subpanel feed from “empty” east service panel. Now we are back to my original question. He wants to install 2-2-4 SEU cable between the east service and subpanel. Everyone is saying it must be 2-2-2-4 cable. I think he also installed a 2-2-4 SEU between west service and shop. What a mess. I can’t verify the shop cable because I’m out of town. Can someone site the NEC stating a 4-conductor cable is necessary? Help please.
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Old 09-22-2012, 05:32 PM   #11
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2-2-4 SEU - Smaller Neutral?


You MUST have four conductors to this sub-panel. If your "electrician does not know this PLEASE find another. Do you think telling him the code section is going to be an effective tactic and make him all of a sudden competent?

If he is even suggesting to run 2-2-4 SEU to ANY new (or even recent) sub-panel proves he does not know what he is doing. PERIOD.
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Old 09-22-2012, 05:34 PM   #12
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2-2-4 SEU - Smaller Neutral?


Subpanels are required to have seperate neutral and ground 250.32


3 wire feed to your detached shop may have been legal at time of installation.

250.32 Buildings or Structures Supplied by a Feeder(s)
or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) sup-
plied by feeder(s) or branch circuit(s) shall have a ground-
ing electrode or grounding electrode system installed in
accordance with Part III of Article 250. The grounding
electrode conductor(s) shall be connected in accordance
with 250.32(B) or (C). Where there is no existing ground-
ing electrode, the grounding electrode(s) required in 250.50
shall be installed.
Exception: A grounding electrode shall not be required
where only a single branch circuit, including a multiwire
branch circuit, supplies the building or structure and the
branch circuit includes an equipment grounding conductor
for grounding the normally non–current-carrying metal
parts of equipment.
(B) Grounded Systems.
(1) Supplied by a Feeder or Branch Circuit. An equip-
ment grounding conductor, as described in 250.118, shall
be run with the supply conductors and be connected to the
building or structure disconnecting means and to the
grounding electrode(s). The equipment grounding conduc-
tor shall be used for grounding or bonding of equipment,
structures, or frames required to be grounded or bonded.
The equipment grounding conductor shall be sized in ac-
cordance with 250.122. Any installed grounded conductor
shall not be connected to the equipment grounding conduc-
tor or to the grounding electrode(s).
Exception: For installations made in compliance with pre-
vious editions of this Code that permitted such connection,
the grounded conductor run with the supply to the building
or structure shall be permitted to serve as the ground-fault
return path if all of the following requirements continue to
be met:
(1) An equipment grounding conductor is not run with the
supply to the building or structure.
( 2 ) There are no continuous metallic paths bonded to the
grounding system in each building or structure involved.
(3) Ground-fault protection of equipment has not been in-
stalled on the supply side of the feeder(s).
If the grounded conductor is used for grounding in accor-
dance with the provision of this exception, the size of the
grounded conductor shall not be smaller than the larger of
either of the following:
(1) That required by 220.61
(2) That required by 250.122

(2) Supplied by Separately Derived System.
(a) With Overcurrent Protection. If overcurrent protec-
tion is provided where the conductors originate, the instal-
lation shall comply with 250.32(B)(1).
(b) Without Overcurrent Protection. If overcurrent
protection is not provided where the conductors originate,
the installation shall comply with 250.30(A). If installed,
the supply-side bonding jumper shall be connected to the
building or structure disconnecting means and to the
grounding electrode(s).
(C) Ungrounded Systems.
(1) Supplied by a Feeder or Branch Circuit. An equip-
ment grounding conductor, as described in 250.118, shall
be installed with the supply conductors and be connected to
the building or structure disconnecting means and to the
grounding electrode(s). The grounding electrode(s) shall also
be connected to the building or structure disconnecting means.(2) Supplied by a Separately Derived System.
(a) With Overcurrent Protection. If overcurrent protec-
tion is provided where the conductors originate, the instal-
lation shall comply with (C)(1).
(b) Without Overcurrent Protection. If overcurrent
protection is not provided where the conductors originate,
the installation shall comply with 250.30(B). If installed,
the supply-side bonding jumper shall be connected to the
building or structure disconnecting means and to the
grounding electrode(s).
(D) Disconnecting Means Located in Separate Building
or Structure on the Same Premises. Where one or more
disconnecting means supply one or more additional buildings
or structures under single management, and where these dis-
connecting means are located remote from those buildings or
structures in accordance with the provisions of 225.32, Excep-
tion No. 1 and No. 2, 700.12(B)(6), 701.12(B)(5), or 702.12,
all of the following conditions shall be met:
(1) The connection of the grounded conductor to the
grounding electrode, to normally non–current-carrying
metal parts of equipment, or to the equipment ground-
ing conductor at a separate building or structure shall
not be made.
(2) An equipment grounding conductor for grounding and
bonding any normally non–current-carrying metal parts
of equipment, interior metal piping systems, and build-
ing or structural metal frames is run with the circuit
conductors to a separate building or structure and con-
nected to existing grounding electrode(s) required in
Part III of this article, or, where there are no existing
electrodes, the grounding electrode(s) required in Part
III of this article shall be installed where a separate
building or structure is supplied by more than one
branch circuit.
(3) The connection between the equipment grounding con-
ductor and the grounding electrode at a separate build-
ing or structure shall be made in a junction box, panel-
board, or similar enclosure located immediately inside
or outside the separate building or structure.
(E) Grounding Electrode Conductor. The size of the
grounding electrode conductor to the grounding elec-
trode(s) shall not be smaller than given in 250.66, based on
the largest ungrounded supply conductor. The installation
shall comply with Part III of this article.
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Old 09-22-2012, 05:45 PM   #13
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2-2-4 SEU - Smaller Neutral?


Are your 200 amp panels each fed from their own meter? Trying to understand what you really have.

The answer is, this "electrician" must use 4 conductors to feed the sub panel. To properly determine the size of the conductors, we need to know if they are copper or aluminum.

As for your NEC request I point to 215.6 requiring an equipment grounding conductor be included in the the feeder.
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Old 09-22-2012, 07:56 PM   #14
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2-2-4 SEU - Smaller Neutral?


Good question. I have one meter for the house. It is mounted on a pole near the utility company’s step-down transformer. For some reason, the utility company does not provide a single 400-amp service in this area. Therefore, it provides two 200-amp services connected to a single meter. The property is in MO. When I lived in VA, I had a 400-amp service.
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Old 09-22-2012, 08:15 PM   #15
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2-2-4 SEU - Smaller Neutral?


Quote:
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Therefore, it provides two 200-amp services connected to a single meter.
This is typical for a residential 320/400A service.

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