# 3-wire feed to sub-panel bonded to main panel **URL:** \ **Category:** Electrical Inspections\ **Created:** [August 16, 2016, 10:05pm UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784 "2016-08-16T22:05:34Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ccurrins](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ccurrins/32/225758_2.png) [@ccurrins](https://forum.nachi.org/u/ccurrins)\ **Post date:** [August 16, 2016, 10:05pm UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/1 "2016-08-16T22:05:34Z")
I have a sub-panel (at left) with a 3-wire feed (H-H-N) from 100 amp breaker at bottom right of service panel, at right. The grounds and neutrals are Bonded at the sub-panel at ground/neutral bar behind all of the wiring at right of panel. The two panels are bonded by metal conduit, as you can see between panels. When the panels are bonded can this be treated like one panel as far as keeping the grounded and grounding conductors bonded. Or does the “sub-panel” at left require isolating the neutral like any other sub-panel would, with the GEC’s bonded to panel? House was built in 1986. ![20160816-27.jpg](https://global.discourse-cdn.com/internachi/original/3X/a/5/a5fe3c83f1d933830e7fc2894eba0176e681780a.jpeg) ---
**Author:** ![Jim\_Port](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@Jim\_Port](https://forum.nachi.org/u/Jim_Port)\ **Post date:** [August 16, 2016, 10:25pm UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/2 "2016-08-16T22:25:33Z")
The grounds and neutral mixed is wrong. They should have been separate. ---
**Author:** ![rmeier2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rmeier2/32/59909_2.png) [@rmeier2](https://forum.nachi.org/u/rmeier2)\ **Post date:** [August 16, 2016, 11:46pm UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/3 "2016-08-16T23:46:23Z")
I agree with Jim also the FMC in this case cannot be used as an EGC. > [@](#): > > 250.118(5) Listed flexible metal conduit meeting all the following > conditions: > a. The conduit is terminated in listed fittings. > **b. The circuit conductors contained in the conduit are > protected by overcurrent devices rated at 20 am- > peres or less.** > c. The combined length of flexible metal conduit and > flexible metallic tubing and liquidtight flexible > metal conduit in the same ground-fault current > path does not exceed 1.8 m (6 ft). > d. If used to connect equipment where flexibility is nec- > essary to minimize the transmission of vibration from > equipment or to provide flexibility for equipment that > requires movement after installation, an equipment > grounding conductor shall be installed. ---
**Author:** ![Jim\_Port](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@Jim\_Port](https://forum.nachi.org/u/Jim_Port)\ **Post date:** [August 17, 2016, 1:27am UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/4 "2016-08-17T01:27:26Z")
Thanks Robert, I meant to add that part about the flex not being able to be used as the egc. ---
**Author:** ![ccurrins](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ccurrins/32/225758_2.png) [@ccurrins](https://forum.nachi.org/u/ccurrins)\ **Post date:** [August 17, 2016, 1:54am UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/5 "2016-08-17T01:54:09Z")
> [@Jim\_Port](#): > > The grounds and neutral mixed is wrong. They should have been separate. Thanks Jim. ---
**Author:** ![ccurrins](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ccurrins/32/225758_2.png) [@ccurrins](https://forum.nachi.org/u/ccurrins)\ **Post date:** [August 17, 2016, 1:57am UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/6 "2016-08-17T01:57:18Z")
> [@Robert\_Meier](#): > > I agree with Jim also the FMC in this case cannot be used as an EGC. So the RMC, short section of conduit in the middle, wouldn’t quality as an EGC? ---
**Author:** ![rmeier2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rmeier2/32/59909_2.png) [@rmeier2](https://forum.nachi.org/u/rmeier2)\ **Post date:** [August 17, 2016, 8:41am UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/7 "2016-08-17T08:41:58Z")
> [@ccurrins](#): > > So the RMC, short section of conduit in the middle, wouldn’t quality as an EGC? It would but not for the feeder, the EGC for the feeder needs to be run with the feeder, either as a compliant metal raceway or as a conductor within the raceway. ---
**Author:** ![ccurrins](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ccurrins/32/225758_2.png) [@ccurrins](https://forum.nachi.org/u/ccurrins)\ **Post date:** [August 17, 2016, 9:03pm UTC](https://forum.nachi.org/t/3-wire-feed-to-sub-panel-bonded-to-main-panel/108784/8 "2016-08-17T21:03:39Z")
> [@Robert\_Meier](#): > > It would but not for the feeder, the EGC for the feeder needs to be run with the feeder, either as a compliant metal raceway or as a conductor within the raceway. Thanks again.