Conduit for SER?

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Old 11-03-20, 01:50 AM
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Conduit for SER?

Hi. I am installing a solar system and need to connect the critical loads (sub)panel to the mains center. The specs are three 8 AWG conductors and a 6 AWG ground. But when you look at 8 AWG NM cable, the ground is always 10 AWG. No go. So I am thinking I'll use 6-6-6-6 SER instead. This will be mounted in a wall between two studs. Are there any code considerations for protecting this concealed short run to protect the SER? E.g., attaching it to the stud, etc.

Also, the old mains panel has a single bundle of Romex branch wires entering through the big top center knockout. I think modern load centers require individual knockouts for each branch. Is there anything I should know about labeling them? My local AHJ does not want to answer any questions pre-inspection. : > (

Thanks fo helping me out!
 
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Old 11-03-20, 02:00 PM
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Hi, post some pics of the panel, is the # 6 independent of the 3# 8s , that would be 2 Hots and a neutral, why not use a short nipple between the panels? Post the specs from this Solar setup.
Geo🇺🇸
 
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Old 11-03-20, 02:45 PM
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Thanks George! Here's the situation.

There's an old crappy Challenger (as in Space Shuttle) semi-flush main load center. Here's a picture. The plywood is the rear of an exterior house wall. You can see all the branch NMs coming through the top. I will be removing four of them from that unmarked cluster and rerouting those to the critical loads subpanel. That will create room for the new conductors coming in from the AC disconnect.


Top of main loads center

It's a combo loads center so the right side is powco meter. The KOs are too small for these new wires,] and I don't have a punch anyway. The idea is to come in from above with the SER 6-6-6-6 from the AC shutoff, which has to be flush mounted outside and in the next 14" stud space to the left. The front of the main panel is also facing outside (but semi-flush).




The conductors of interest are marked with the "3" on the left. They are supposed to be three 8AWG THHNS, plus a 6 THHN ground.


On the left of the box is a double-stud. I don't have a close quarters drill, so I am going to go in from the outside, across, and into this cavity. The only availble KOs are on the BOTTOM of the main loads center, and it's super hard to get there. The SER would drop down from above and go in the center with the remaining branch 14/3 and 12/3 branch cables. I hope this makes sense. I'm assuming I should use copper, and not aluminum, btw. Thanks for taking this on!



 
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Old 11-03-20, 04:05 PM
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Hi, this a bit hard to understand, so this bi directional meter will mount next to an existing meter? You will not be allowed to put multiple cables into one connector, unless the connector is rated.
What does the F represent?
Why flush mounted outside?
Can you post some pics of where this setup will be installed ?

Geo 🇺🇸

 

Last edited by XSleeper; 11-04-20 at 06:53 PM. Reason: Removed tagline
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Old 11-03-20, 04:47 PM
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What is the condition of that Challenger panel ?
They have been known to be problem/hazardous panels and some insurance companies will no longer cover claims as a result of a panel failure.
Challenger panel problems
 
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Old 11-03-20, 10:23 PM
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Thanks George.

This setup has passed AHJ approval on paper.

There is only one electric meter. It's on the existing main service panel. 125 Amp with 100 amp busbars. Rating/derating is not an issue. I am physically transferring some of the existing circuit breakers from the main to a new subpanel (not separately metered).But that's not really relevant to my question(s). I have to have an AC disconnect sitting between the inverter and the main panel. It is mounted outside so firemen can get to it. I need to run 8-8-8-6 conductors from that disconnect to the mains panel.

My questions are:

1. Running an SER 6-6-6-6 in a stud cavity. Do I need to secure it to the side of a stud, like romex? Or can it just run in the center of the cavity between the two boxes?

2. This 22-year-old service entrance box has unlabeled branch circuits (tho there's a Legend on the door).. Do you know the labeling requirements per the current code? I don't. Do I need to take each NM cable?

3. You mentioned that current load centers require separate KOs for each branch circuit. Are you suggesting that the AHJ is likely to force me to replace this main loads panel? (I don't need that in my life!)

I hope this is clear. Thanks for your patience.


I am attaching the relevant section of the schematic.




The main panel is on the left. The AC Disconnect ("F") is on the right. "3" refers to the wiring key: Three 8-AWGS THHNs, plus a 6 AWG ground. Since there's no NM cable like that (It's all 8-8-8-10), I need something with a 6 AWG ground. Hence SER 6-6-6-6.
 
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Old 11-04-20, 02:26 AM
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Some solar systems still require utility power to work. Without utility power the loads will not be powered just from the solar.
 
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Old 11-04-20, 05:39 AM
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Ser

Hi, how long will this SER be? can you use flex and individual conductor? most connectors are only rated for 2 cables, as for labeling circuits I doubt the AHJ will make label existing, I would probably label anything you move.
Why does this meter setup need to be flush mounted?
Geo 🇺🇸
 
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Old 11-05-20, 12:48 AM
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Thanks for your help on this PJ. You are great as ever.

Bottom line: I need a very short run of AWG 6-6-6-4 inside a wall cavity.

This is for a 50-amp branch circuit from my main box, through an AC disconnect switch.

I don't know what kind of conductor to use from the AC Disco to the breaker. The distance of the run is about 12" or 18".

The available 1" knockouts on the mains box are too small to hold a 6-6-6-4. I don't have a KO punch (haha) to enblarge them. (Maybe a hole saw? Hard to drill in there.) Anyway, all the branch circuits feeders are bundled together and feed through the big hub hole at the top of the mains box. (Hot service entry conductors enter through the bottom of the box).

this mains box is semi-flush mount. So there's limited room in the wall cavity. And Challenger was awful, but it is in decent shape and hasn't burned up (yet) like its namesake.

I would like to put this 6-6-6-4 in though this hub hole. But now I have just read/learned about derating conductors in crowded raceways. *TABLE 310.15(B)(3)(a) Adjustment Factors for More Than Three Current-Carrying Conductors. The derating just killed the SER idea.

Going in through a stud from the adjacent cavity is not a pleasant option. It's actually a double stud, and access would be difficiult.
What to do????
 
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Old 11-05-20, 05:51 AM
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For the derating tables to apply, the closely run conductors must exceed 24 inches.
 
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Old 11-05-20, 11:24 AM
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Thank you!!!! You made my year. No that's too easy. Decade.

It was buried in the Platt catalog:

https://www.platt.com/platt-electric...px?zpid=233024
 
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Old 11-08-20, 04:27 AM
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The cables entering the top of the panel do not meet code now. You cannot insert the SER the same way. They need to be clamped to the enclosure with proper connectors.
 
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Old 11-08-20, 08:56 AM
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thank you pcboss.

Just to clarify: this is part of a branch circuit, and the conductor would leave the AC disconnect with a clamp connector and enter the main box as part of a bundle through the hub hole at the top about 8 inches away, all inside a wall cavity.

I went to the electrical supply store yesterday. It was hard to understand the Chinese man who helped me (through his mask), but he sold me 2 feet (avoid derating) of copper 8/3 "Lumio"? jacketed cable.

The ground in the jacket was too small gauge so he sold me a separate 6 AWG coated ground wire and said I could strap/tie it to the 6/3 because it was "not a conductor".

Does this still sound like a violation?
 
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Old 11-08-20, 12:34 PM
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The cables need to be clamped to the box. Shoved through the hub is not compliant.
 
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