I would like to clean up a 30-year-old panel that is obsolete and a potential hazard.
I want to replace my GTE / Sylvania (Zinsco-compatible) breaker panel. A problem is that this panel is about 12" wide and is flush against studs. Rather than carve up the wall to put in headers for a wider panel, I came up with "Plan B". My "Plan B" is to:
　
(1) Mount the the wider panel (a Square-D Homeline HOM20L125C) one stud over (next to the existing Zinsco),
(2) Pull all the guts out of the Zinsco except the ground bar, and
(3) Turn the Zinsco into a large junction box, both for feeders and circuit wiring.
　
I can cut a nice neat rectangle in the drywall for the Homeline with some vertical play to match up holes through the common stud and between the two panels. I expect to have to cut new knock-outs in one of the panels.
　
[Q1] The Zinsco is fed from a 100A main disconnect outside. The #2 AL feeders may not be long enough to connect to the lugs in the Homeline. I have not encountered AL-to-AL connectors for #2 wire. If not long enough, what is the best way to extend these feeders -- less than 12"?

[Q2] Ground continuity to the outside disconnect panel is through Rigid Metal Conduit and a separate #10 Green from the outside panel to the ground bar. There is also a #6 Green from the ground bar to a pipe somewhere. Is it sufficient to run another Green from the Zinsco ground bar to the Homeline ground bar? Or should it be run from a connector attached to the RMC? What gauge wire should this be?
　
Thank you,
Lynnx

 

You may want to see if the opening between the studs was reduced by adding a false stud next to one side of the panel.

The NEC requires the unfused conductors in a building to be as short as practical. Adding the new panel farther away does not satisfy this, but your inspector may allow it. I would ask before you go through all that effort.

I would not splice the conductors feeding the panel, but would pull new longer ones.

 

Thanks, pcboss.

I will check for a false stud.

Does the main disconnect breaker in the outside panel let the feeders for the inside panel be considered as "fused"?

 

If your disconnect outside has fuses, or circuit breakers, you would be fine doing what you propose. This would satisfy the NEC as the conductors are protected, and therefore, can be any length.

 

There is no need to bond to the RMC.

The GEC should be bonded to the utility neutral in the outside disconnect box. The conductor bonded to the cold water inlet should go directly there without passing through the distribution panel. The conductor between the bond in the outside disconnect and the distribution panel should enter with the other three feeders and should be green insulated #6 AWG copper.

#2 AWG aluminum has a rated ampacity of 75 amps at 60[SUP]o[/SUP] C. Do you have #2/0 aluminum conductors for an 100A service? You should replace those feeders with copper feeders that are long enough to make it to the lugs without splicing, in order to eliminate the potential for galvanic corrosion, if at all possible.

You already have some good advice in the earlier posts.

 

Dwelling unit or residential service entrance conductors can be either #2 aluminum or #4 copper. That being said, I'd also recommend using continuous copper conductors rather than aluminum. In addition, the NEC allows #2 aluminum or #4 copper service entrance conductors to a dwelling unit, but that is a minimum requirement. I recommend using #3 copper.

Should you decide to use aluminum conductors, a #4 aluminum ground must be run between the disconnect and the service panel along with the two ungrounded conductors and neutral conductor.

 

Starting from the electrical vault in the street, there are two hots and one neutral in RMC to a large outside panel with two meters and two main disconnect breakers for two townhouses. One of the townhouses (one common wall) is mine.
　
From this large (double) disconnect panel, there are two RMCs (one for each townhouse), each carrying two hots, one neutral (AWG #2 AL) and one ground (AWG #10 CU) to two Zinsco-compatible distribution panels. In each townhouse, one green wire (AWG #6 CU) goes from the the panel ground bar to a cold water inlet somewhere in the unit.
　
Can the RMC between the (double) disconnect panel and an inside panel take the place of a separate ground conductor? If the green #10 CU were replaced with #6 CU (for only one distribution panel), would this be enough? (My neighbor does not want to put any money into his rental.)
　
There are two cold water inlets that now connect to the inside panels. Should one of these cold water inlet conductors go all the way to the (double) disconnect panel without touching the ground bar in the associated distribution panel?
　
Thanks. Hope this makes sense.

Mod Note: I removed the formatting from this post before I read Ray's note about the formatting!

 

Lynx please use the forum editor to write your post. If you look at your post you will see all the improper, unneeded formatting the editor you are using is adding. I partly edited your first post. I am leaving your second post so you can see the problems.

 

You cannot modify the electrical system of a property unless you own it.

 

Clarification: My common-wall neighbor is the owner of his townhouse. He does not live there; he rents it.

 

Local code may not permit unlicensed electrical work on a multifamily residence even if you own your half. Even if allowed you are taking on a lot of liability and may void any insurance.

Is this a shared meter?

 

Two meters, Ray.

I started out getting bids from several licensed electricians. All of them were not familiar with NEC (Article 440) sections relating to my "Hermetic Refrigerant Motor-Compressor", including the HVAC contractor's electrician, and estimated nearly $900 to run a new circuit to the condenser. They also provided mis-information on the availability of a suitable breaker (for the condenser circuit) that would fit in my panel and instead proposed panel replacement.

I am pretty disgusted, but grateful that I have found this wonderful resource. I am holding off for now while I think about other issues raised.

Thanks,
Lynnx

PS... I only use forum links to post now, so I should avoid spurious formatting. Thank you.

Mod Note: If you click on "Reply" and type directly into the dialogue window that opens, you should avoid including extraneous format controls. You can use the tools in the bar at the top of that window to add any formatting you actually need.

 

Sorry. What do I have to do to exclude formatting when I cut and paste? I will try passing it through Notepad a/o look around the forum for help.

 

Why are you cutting and pasting? If you have to use another editor compose as text only. No rich text or HTML. Composing in Notepad would be okay.

 

I think I missed something, what was the question about your condenser? Was it just sizing the breaker and circuit?

I think most on this forum would agree with panel replacement.

 

Joe, it is in his other thread. He had his A/C condensing unit replaced and then the 30 ampere circuit breaker would occasionally trip. The HVAC contractor installed a 40 ampere CB and then Lynnx questioned the advisability of putting a 40 ampere CB on #10 conductors. He asked several electricians who told him it was wrong but finally found out that it WAS acceptable. Then he stated the CB didn't properly fit the panel cover and that the proper CB was unavailable. That lead into his looking at a full panel replacement.

 

Ohhh, OK, gotcha, I must have missed the other thread. And yes, it is acceptable to have #10 conductors and a 40 amp circuit breaker under some circumstances when motors are involved.

 

This thread: http://www.doityourself.com/forum/ai...l-conduct.html

 

I definitely didn't see that thread. I don't generally look at the A-C forum while my heat is on. Well, I might, but don't usually have the extra time (yet).