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.
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 - 08/02/0602:26 AMRe: Neutrals in Panel Upgrade w/Junction Box
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 - 08/02/0608:19 AMRe: Neutrals in Panel Upgrade w/Junction Box
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 - 08/02/0604:23 PMRe: Neutrals in Panel Upgrade w/Junction Box
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
#68290 - 08/02/0606:21 PMRe: Neutrals in Panel Upgrade w/Junction Box
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 - 08/02/0606:31 PMRe: Neutrals in Panel Upgrade w/Junction Box