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Posted By: ehill Neutrals in Panel Upgrade w/Junction Box - 08/01/06 11:48 PM
Hello,

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?

Thanks.

Eric
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.
Posted By: ehill Re: Neutrals in Panel Upgrade w/Junction Box - 08/02/06 06:26 AM
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.
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.
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.
Posted By: ehill Re: Neutrals in Panel Upgrade w/Junction Box - 08/02/06 08:23 PM
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.
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
Posted By: JJM Re: Neutrals in Panel Upgrade w/Junction Box - 08/02/06 10:21 PM
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:

[Linked Image from leviton.com]

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:

[Linked Image from cache.smarthome.com]

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.

Joe

[This message has been edited by JJM (edited 08-02-2006).]
What about putting a sub-panel in the attic?
Posted By: ehill Re: Neutrals in Panel Upgrade w/Junction Box - 08/02/06 11:10 PM
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.
For running the separate conduits?

Non in metal conduit or boxes, you won't

300.20 Induced Currents in Metal Enclosures or Metal Raceways.
(A) Conductors Grouped Together.
Where conductors carrying alternating current ar installed in metal enclosures or metal raceways, they shall be arranged so as to avoid heating the surrounding metal by induction. To accomplish this, all phase conductors, and where used, the grounded conductor and all equipment grounding conductors shall be grouped together

[This message has been edited by electure (edited 08-02-2006).]
Dnk, I would question the accessibility of a sub panel in an attic. You might also see some problems with ambient temperatures down here.
I don't know what he's got gfretwell.

He may have an old victorian style with them big attics, or a little cape cod with no access.

Just thought I'd through it out there....
Posted By: trobb Re: Neutrals in Panel Upgrade w/Junction Box - 08/04/06 03:34 AM
My parent's attic has a 50 or 60 degree slope each side, so it's 30' tall roughly. Gets over 150 degrees in the summer, but there is great access (pull-down ladder from 1927, no hinges- all one big unit that puls out and down). It's really nice to work up there, you can get 4'+ height right next to the edge of the attic.
Posted By: ehill Re: Neutrals in Panel Upgrade w/Junction Box - 08/04/06 03:46 AM
I really resent that post. ;-)
I'd like to resurrect this discussion because I have several installations where I am probably out of compliance. Many times when upgrading to a larger panel I reuse the abandoned box as a junction box, gutting the interior but leaving the neutral bar, then covering the old panel with a sheet of tin. Sometimes I have set a separate ground bar & pulled all the bares off the neutral bar. I then typically run a #8 ground and a #6 neutral to the new panel in an oversized raceway, along with the circuit conductors. For residential I have used # 12's-the distance usually is 10-15 feet and the load diversity in homes is so great that I have never experienced any problems. I understand the derating part of the code, but also fall back on Table B 310-11.
In another area of this thread the remote J box to collect exist circuits was discussed. I have several commercial jobs where I pulled 12-# 10's, 1#8 Gr. & 1#6 N into 12.12.6 boxes above restaurant kitchen ceilings. I fab'ed. a neutral bar by splitting a length of 1-1/4 pvc lengthwise, bolting a gr. bar to this, then bolting the assembly to my junction box. (this also can serve as a quick, inexpensive isolated ground bar)Sometimes I have landed the hots on a barrier terminal strip, other times I make them up with Scotchloks. All the branch appliance circuits are fed into this box(# 12 MC)As I recall, the inspector guy looked at my work and smiled, gave me the OK. What I'm getting from the discussion is that I should run 2 pipes to cut the number of current carrying conductors down. Your comments are appreciated. And thanks for the information on the supplemental X-10 hardware.
As soon as you run 2+ pipes, you need to keep track of your neutrals...the neutral for a circuit must be in the same pipe as the hot. So, in your case, you'd have 2 neutral bars, and 2 neutral wires, one in each conduit. But, you could use smaller HR wires on your hots. You'd have to decide which option makes more economic sense. My feeling is that if it's a long conduit run, I'd rather have oversized conductors if it means I only have to run and pull through one conduit, but with today's copper prices, maybe 2 smaller pipes makes more $$$ sense. Perhaps somebody here that has all the pricing in a estimating program could give us rough numbers?

As for your neutral bar, that's fine in a pinch, but you should really use a listed, factory built neutral bar if you do this a lot. If I opened up your Jbox and saw that, I might doubt other aspects of your installation.

FWIW, I've used the DIN rail terminal blocks(on the hots) for setups like this, they are quick to assemble, and there is no crimping, etc.
Posted By: LK Re: Neutrals in Panel Upgrade w/Junction Box - 09/12/06 11:27 PM
"What about putting a sub-panel in the attic?"

If the attic is not a goood location, than there may be another location, but the sub panel may be a better way to go.
Posted By: e57 Re: Neutrals in Panel Upgrade w/Junction Box - 09/13/06 01:02 AM
I put one in an attic once... But it was a rare situation.

It had the headroom and workspace and access.... And it rarely ever breaks 80F here.... [Linked Image] There were also two AC units in there too, doubt they ever get used.....

As far as getting neutrals mixed up, band them together with thier conductors with tape, or number them with thier circuit numbers. Number books are cheap.... Tape is real cheap!

Almost Fried, I have done simular things with using an old panel as a junction box and leaving the nuetral bar and grounds, but only under 2' ands in a large nipple so it fell under the 2' rule for derating. You might be able to go a further distance in a gutter... But not 2 conduits. (Magic number is 9 or it is a waste of copper to up-size IMO) And I don't think I would ever MAKE a neutral bar.
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