# Incorrect wire size for a 100 amp circuit breaker **URL:** \ **Category:** Electrical Inspections\ **Created:** [February 22, 2020, 4:12am UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758 "2020-02-22T04:12:20Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![mbruchs](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mbruchs/32/180995_2.png) [@mbruchs](https://forum.nachi.org/u/mbruchs)\ **Post date:** [February 22, 2020, 4:12am UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/1 "2020-02-22T04:12:20Z")
Observed what appeared to be a #8 copper wire (red, black and white) installed on a 100 amp circuit breaker in the main Square D electric service panel and connected to a 100 amp circuit breaker in a General Electric sub panel. I think the wire should be at least 2-gauge. Trying to verify before I write it up. Any help is appreciated. ![05b905dd-bad1-4a79-a5b5-65f74dc16f8a-thumbnail-large](https://global.discourse-cdn.com/internachi/original/3X/e/8/e89c411bcfa579575f22ab536c316432339468a7.jpeg) ![d16fc6c1-459e-411e-8236-6828a9e1f34d](https://global.discourse-cdn.com/internachi/original/3X/a/c/ac11bac5883c9d4cb9d9c40ed1c51c0a851b5758.jpeg) ![electric pics](https://global.discourse-cdn.com/internachi/original/3X/3/d/3dc874da1bdc048e98aca57b5ad994b9860c6c9a.jpeg) ---
**Author:** ![mparks2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mparks2/32/172915_2.png) [@mparks2](https://forum.nachi.org/u/mparks2)\ **Post date:** [February 22, 2020, 4:22am UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/2 "2020-02-22T04:22:34Z")
Am I seeing only 3 wires to the sub? Is that a green bonding screw? ---
**Author:** ![srechkin](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/srechkin/32/180448_2.png) [@srechkin](https://forum.nachi.org/u/srechkin)\ **Post date:** [February 22, 2020, 4:52am UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/3 "2020-02-22T04:52:37Z")
Are you sure it’s #8, it doesn’t look it from here. ---
**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:** [February 22, 2020, 12:42pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/4 "2020-02-22T12:42:32Z")
Look like it could be #3 AWG which is good for 100 amps. They have removed the jumper between the two neutral bars and made the one on the left the EGC bar by installing the green screw. Only thing missing is the EGC with the feeder which could be the metal raceway if one was used for the feeder. ![](https://global.discourse-cdn.com/internachi/original/3X/a/c/ac11bac5883c9d4cb9d9c40ed1c51c0a851b5758.jpeg) ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:09pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/5 "2020-02-23T14:09:18Z")
Just a quick question… What gauge wire should a 150 amp panel require. ??? SE conductors I mean. ??? ---
**Author:** ![rlewis5](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rlewis5/32/337040_2.png) [@rlewis5](https://forum.nachi.org/u/rlewis5)\ **Post date:** [February 23, 2020, 2:22pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/6 "2020-02-23T14:22:16Z")
![wiresize](https://global.discourse-cdn.com/internachi/original/3X/6/5/652aafaacae724e9c3e79232506b656ebbd43eb7.jpeg) ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:23pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/7 "2020-02-23T14:23:04Z")
Thanks Roy ---
**Author:** ![mparks2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mparks2/32/172915_2.png) [@mparks2](https://forum.nachi.org/u/mparks2)\ **Post date:** [February 23, 2020, 2:24pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/8 "2020-02-23T14:24:20Z")
that’s only if you are feeding the main panel -100% of the load. ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:30pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/9 "2020-02-23T14:30:20Z")
Yes main panel. I am getting my conductors and breakers together in an effort to have all the components ready to upgrade my service panel. Also I like to question the experts at H Depot and cross reference this information. Thank all for the info. ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:34pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/10 "2020-02-23T14:34:06Z")
Also copper SEC are always favored over aluminum correct??? ---
**Author:** ![rlewis5](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rlewis5/32/337040_2.png) [@rlewis5](https://forum.nachi.org/u/rlewis5)\ **Post date:** [February 23, 2020, 2:34pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/11 "2020-02-23T14:34:46Z")
Not necessarily. Correct size is. ---
**Author:** ![mparks2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mparks2/32/172915_2.png) [@mparks2](https://forum.nachi.org/u/mparks2)\ **Post date:** [February 23, 2020, 2:37pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/12 "2020-02-23T14:37:12Z")
> [@jzehel](#): > > Also copper SEC are always favored over aluminum correct??? Copper doesn’t ‘move’ as much alum. Expand and contract. ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:40pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/13 "2020-02-23T14:40:10Z")
So 1 AWG copper SEC is required for a 150 panel. Correct ??? And that amperage would support a 1500 sf home with an electrical charging station in garage for an electric vehicle correct??? ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:41pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/14 "2020-02-23T14:41:41Z")
Is copper more expensive than aluminum. ---
**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:** [February 23, 2020, 2:44pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/15 "2020-02-23T14:44:42Z")
> [@jzehel](#): > > So 1 AWG copper SEC is required for a 150 panel. Correct ??? And that amperage would support a 1500 sf home with an electrical charging station in garage for an electric vehicle correct??? The NEC no longer uses a table to determine the SEC size for a dwelling, now they specify that the SEC’s must have a minimum ampacity of 83% of the service OCPD size. You would need a load calculation to accurately determine the service size. Car chargers come in various sizes. With a 100 amp charger in an all electric home 150 amps might not be large enough. Copper is much more expensive. ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:47pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/16 "2020-02-23T14:47:04Z")
I don’t want sub-standard wire in my new panel. I want the best preforming components in the panel. Also, when I leave this home, the next guy won’t have to worry about the power supply. ---
**Author:** ![jzehel](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jzehel/32/192274_2.png) [@jzehel](https://forum.nachi.org/u/jzehel)\ **Post date:** [February 23, 2020, 2:48pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/17 "2020-02-23T14:48:28Z")
Wow, now I’m confused ---
**Author:** ![srechkin](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/srechkin/32/180448_2.png) [@srechkin](https://forum.nachi.org/u/srechkin)\ **Post date:** [February 23, 2020, 2:49pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/18 "2020-02-23T14:49:18Z")
It’s very simple… do load calculation and use copper if you’ve got $$$ don’t cheap out on service size. Upgrading 2s is more expensive. ---
**Author:** ![mparks2](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mparks2/32/172915_2.png) [@mparks2](https://forum.nachi.org/u/mparks2)\ **Post date:** [February 23, 2020, 2:50pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/19 "2020-02-23T14:50:26Z")
> [@jzehel](#): > > Wow, now I’m confused This is an old example. Maybe some else has a newer one. [ResidentialLoadCalculations2.xls](https://forum.nachi.org/uploads/short-url/uxobxG8lqlzTeaQssIJL05h3d9l.xls) (1.2 MB) ---
**Author:** ![mgoldenberg](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mgoldenberg/32/89265_2.png) [@mgoldenberg](https://forum.nachi.org/u/mgoldenberg)\ **Post date:** [February 23, 2020, 2:51pm UTC](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758/20 "2020-02-23T14:51:37Z")
What are you charging? a Tesla or something? Jut go with/upgrade to 200 amp on 2/0 cu. [Next page](https://forum.nachi.org/t/incorrect-wire-size-for-a-100-amp-circuit-breaker/161758.md?page=2)