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#68283 - 08/01/06 04:48 PM Neutrals in Panel Upgrade w/Junction Box
ehill Offline

Registered: 08/01/06
Posts: 27

Doing a main panel upgrade (200A) and move, along with moving service UG.

1960’s 100A Zinsco main panel. Single-phase residential.

existing main panel --> attic junction box --> new main panel

The purpose of the attic junction box is to provide an easy way to abandon the converted Zinsco when the house is rewired in the future. For any new circuits, the attic junction box will provide an easy path from the attic to the new panel.

I’m contemplating the best method of running the neutrals: (a) Running a couple of large neutrals; (b) running individual neutrals per circuit; (c) a combination of the two. Run is about 75’.

House has lots of X10 devices. Don’t know if there are any issues here, but can’t afford to have any problems.

The issue that comes to mind is GFCI breakers. Wouldn’t be able to use them unless individual neutrals were run.

Any thoughts?



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#68284 - 08/01/06 06:22 PM Re: Neutrals in Panel Upgrade w/Junction Box
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
I have encountered a few places where neutrals got combined at places remote from the panel.

While, in theory, it would work... and code allows it... I really object to the practice. Neutrals are not identifable, and it is too easy to mis-connect them when you next work in the box. The end result can be... as it was for me (oops).... $300 worth of surge suppressors and power supplies to replace, as you've managed to create a 240 circuit soemwhere.

IF I were to do it, I would run a large neutral (say, #6) from the panel to a pull can. In that pull can, I would mount a neutral bus (insulated from the can), and terminate the neutrals there. I would NOT use wirenuts, or have more than one wire return to the panel.

#68285 - 08/01/06 11:26 PM Re: Neutrals in Panel Upgrade w/Junction Box
ehill Offline

Registered: 08/01/06
Posts: 27
What would you do with new circuits and with rewiring the house (long-term)... Land the neutrals in the pull box, or take them to the panel?

I'm thinking that landing all the neutrals in the pull box is the better way to go.

Long term, when the house is rewired, the pull box would be much cleaner if there were neutral and ground bars. That would leave the only wirenuts on the hots.

#68286 - 08/02/06 02:32 AM Re: Neutrals in Panel Upgrade w/Junction Box
Texas_Ranger Offline

Registered: 12/17/01
Posts: 2346
Loc: Vienna, Austria
Phew! That's another code difference between the US and most European countries yet unknown to me.
Here there's a somple rule: one hot, one neutral, all the way up to the panel the circuit is originating from. Circuits that are on different breakers MUST NOT share a neutral. Only exception: split circuits taken from one 3ph circuit may have a shared neutral and are not even required to be on a 3 pole breaker as long as there is a 3 pole switch somewhere upstream.
Generally that practice is extremely frowned upon though as people say with small wires like used in household wiring broken neutrals are far too likely. So hardly any multiwire circuits here.

#68287 - 08/02/06 05:19 AM Re: Neutrals in Panel Upgrade w/Junction Box
electure Offline


Registered: 12/24/00
Posts: 4227
Loc: Fullerton, CA USA
Running all these circuits on the same grounded conductor does create an issue.

Since the circuits must be in a raceway together, derating the conductor ampacity will be required.
For instance, take 15 20A circuits together with your big neutral through the same conduit.
16 conductors in the same raceway must be derated to 50%.

Each of your #12s just became a #8.
If you have nonmetallic raceway or flex, your equipment grounding conductor must now be a #8 also.
Now basically double the size or the raceway, and your neutrals, and your in there!

Sounds like economic suicide to me.

Just my opinion, but I'd take the homeruns back from the box with individual 3 wire cables YES MULTIWIRE CIRCUITS, and install a raceway with a pull string in it from the panel to the box for future additional circuits.
No need to reinvent the wheel, many have tried, and it's still round.

#68288 - 08/02/06 01:23 PM Re: Neutrals in Panel Upgrade w/Junction Box
ehill Offline

Registered: 08/01/06
Posts: 27
My thought was to use enough conduit so that after derating, the 15A circuits would be on 12, and the 20A circuits would be on 10.

There are (2) 15A circuits and (10) 20A circuits. (The 30A and 40A circuits would be rewired to the new panel immediately after cutover.)

That would come out to 3 runs of 1/2" for the hots, and one additional 1/2" for the neutral (#6) and ground (#6).

The alternative would be to use NM.

Identifying the neutrals would take several hours, but can be done relatively easy if the neutrals are removed from the bar in the existing panel.

About 50' of the run is the garage. The joists are exposed, and clearance is less than 39”. I could run NM on top of the joists in an open tray.

#68289 - 08/02/06 01:59 PM Re: Neutrals in Panel Upgrade w/Junction Box
gfretwell Offline


Registered: 07/20/04
Posts: 9058
Loc: Estero,Fl,usa
All Electronics sells some terminal strips that are U/L listed for up to 35a. (rated 10 ga or smaller wire) I am thinking the next time I do something like this I will look into that approach for my "big ugly junction box". Then you could still use RX in and out while maintaining some rhyme and reason to the connections. You can probably use garden variety ground bus bars for the EGCs
Greg Fretwell

#68290 - 08/02/06 03:21 PM Re: Neutrals in Panel Upgrade w/Junction Box
JJM Offline

Registered: 10/31/05
Posts: 102
On the X-10 question... X-10 signals don't jump phases well, so you positively MUST include an amplifier/repeater like the Leviton # HCA02-10E on this job, otherwise you're gonna be dealing with call backs:

You usually can mount the amplifer in a standard gang (3 or 4) box with cover. The amplifier is shoud have it's own DEDIDICATED breaker on each phase (double pole). The HO might even be surprised how well the X-10 works when you're done!

Don't waste you're time with bridges/couplers, like the Leviton # 6299 -- a waste of time.

I found that on a lot of those old Zinco systems, they simply moved the bar on the back of the breakers to keep everything X-10 on one phase to keep the X-10 devices happy... so much for balancing loads.

It's also a good idea to include a whole house blocking coupler, Leviton # 6284 to prevent neighbors X-10 signals from interfering with your customers devices:

As you can see, it slips right over the neutral line, so a service upgrade is an opportune time to install it.

And my opinion is to run seperate neutrals directly to the panel, this way you don't run into problems with GFCI and AFCI breakers should they be installed in the future.


[This message has been edited by JJM (edited 08-02-2006).]

#68291 - 08/02/06 03:31 PM Re: Neutrals in Panel Upgrade w/Junction Box
Dnkldorf Offline

Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
What about putting a sub-panel in the attic?

#68292 - 08/02/06 04:10 PM Re: Neutrals in Panel Upgrade w/Junction Box
ehill Offline

Registered: 08/01/06
Posts: 27
There's already a 6299 phase coupler installed. The blocking 6284 is spec'd already. (Or, something similar.)

There were some problems getting the X10 to the far end of the house, but a well-placed filter on the fridge took care of that problem. That took a couple of hours to find that problem.

Thanks for the information, though. I appreciate it.

(I don't know exactly how X10 works on the neutral side, and wondered if there were any issues with running a single neutral back. Didn't think so, but I wanted to bring it up, just in case.)

Thanks again.

There's no way to install a sub-panel and maintain clearance.

The roof is really shallow. For the most part, the only crawl space is down the middle of the house.

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