Re-Wiring an Old California Home 1

[STEPE]

Gentlemen,
A new and larger circuit breaker panelboard with main breaker is needed to replace an existing breaker panel and sub-breaker panel in a single residential garage, in california. The plan is to use the sub-panel as a feed-thru j-box and remove the existing breakers, as the loads will be fed by the new main breaker panel.
The home was constructed circa 1955 and has no ground wire in the house's receptacles, they all being 2 prong.
Is a reference earthground needed to be established with this new panelboard as well as a water pipeline ground? There are no ground wires in the home.

 

[lyledunn]

Stepe,
Let me tell you how it would be in UK. An earth would be provided by utility or consumer would provide his own, an earth spike usually (with additional residual current protection). Each receptacle (socket outlet) would have an appropriately sized circuit protective conductor (earth wire) run to it.
The water pipes (if metallic) and other incoming services would be bonded to the installation earth.
The idea is to provide co-ordination between the protective devices employed and the earth fault current so that disconnection occurs in a stipulated time. The bonding is designed to minimise any voltages that might appear between installation metalwork and other services metalwork during the earth fault.
(Remember our nominal voltage to earth is 230v) Regards,

Lyledunn

 

[meihm]

Several items for your consideration:

1. Although you do not mention it, if the the existing panel was the original service panel for the structure, it was required to have a ground to earth (probably via a cold water pipe). This original ground must be isolated from the old panel's neutral bus and equipment ground (to avoid multiple ground points for the service neutral).

2. Yes, the new service panel must be grounded (equipment ground and neural must be grounded), and yes the equipment ground must be extended to the original panel enclosure (used as a junction box)and effectively bonded.

3. As you are probably aware, replacement 2 wire receptacles are rare and not easily found.

4. The National Electrical Code (and the California Electrical Code) allow the existing 2 wire receptacles to be replaced with grounded type (3 wire receptacles) providing the existing 2 wire receptacle circuits are ground fault protected and the 3 wire receptacles are noted (with a label or sticker) as ground fault protected.

5. The downside is that devices (such as computers) are not properly protected (by the absence of the ground conductor) when plugged into such a ground fault protected 3 wire receptacle connected to a 2 wire circuit. Further the absence of a ground conductor indicates that a surge protector does not have a ground path to divert the energy around (bypassing) the "protected" equipment.

6. I very strongly recomend that you discuss his situation with your local electrical inspector before proceeding.

meihm

 

[busbar]

Good points have been addressed here. As an alternative to conversing with the local inspector, {they tend to be heavily scheduled, and often prefer to talk in usual electrical-code terms} an electrical contractor should have his ear to the ground on local requirements. Recognize that neither seeing your building and wiring condition will limit accuracy of off-the-cuff advice. If safety is of concern, getting a remodel permit from the building authority {inspection department} will more readily assure completion to accepted standards.

Replacement of electrical panels is common, particularly if air conditioning has been added. Gutting of a subpanel is an accepted custom, but as mentioned needs to be by a person familiar with code practices.

 

[mainepepmp]

NEC is not my forte, but personal experiences like you're in the middle of, and experience with grounding qualify me to at least present a "sidewalk superintendent" view.

I believe NEC requires a separately-derived ground cable to be run between the new (new main) and existing (new sub-panel) panels.

You will want to use the earth ground at the new main panel as the single junction for all earth grounds in the building (for the reasons already pointed out, as well as to limit your risk of electric shock). NESC (maybe NEC, too, I'm unsure) requires single-point grounding.

Proceed as recommended above if contracting. If DIY, install new panel, have electric company move service from existing to new panel, run wire from new panel to main breaker of existing panel (along with new ground wire), remove existing earth ground connection to pipes, power new panel, and repower existing panel from new main panel.

Have an electrician do the work; the coordination with the electric company will be a nightmare if you're not perfectly clear on the details, expectations, and requirements.

You don't mention if existing panel is fuses or CBs; my guess is the former, given use of ungrounded outlets. Save yourself some hassle down the road -- upgrade the existing panel at the same time. (You may not be able to do what you propose without this, as '01/'02 changes to NEC required in-panel GFCI breakers for bedrooms, I think.)

 

[meihm]

Mainepepmp mentioned GFCI required circuit protection for bedrooms: right neighborhood; wrong address.

Starting with the 1999 National Electrical Code/2002 California Electrical Code, circuits serving bedrooms require AFCI (Arcing Fault Circuit Interrupter) protection.

Only your local inspector can determine if he will allow the existing wiring to remain with GFCI protection and 3 wire receptacles or if the building must be re-wired with 3 wire circuits and AFCI circuit breakers.

Since you don't mention the community or the wiring method (flex conduit with wire vs Romex cable), I assume that the wiring is in Romex. If true, it should be obvious that you really DO NOT want to rewire the existing structure.

You haven't discussed how you are going to feed the new wiring from the new panel (and new circuit breakers) to the existing panel/junction box. If you run a single conduit with the branch circuit wires, a single grounding wire will probably be adequate. If, however, you decide to run multiple branch (Romex) cables you need to discuss how to terminate the individual grounding wires (in each cable) with the inspector.

If you are a homeowner doing your own work, your local inspection authority pobably has a homeowner permit process.

It is my experience that inspectors are more than wlling to discuss an issue beforehand, and less willing after its done. Asking costs little or nothing, but making changes after the fact may not be so easy or so cheap.

Meihm (PE, CA)

 

[STEPE]

Thank you gentlemen for taking the time to help on this issue. I would like to answer a couple questions asked by Meihm and ask a couple more myself on this matter.
Yes the house is wired in two wire romex, and the new panel will remove and replace the current main panel.
I am insisting that the owner maintain the ground connection of the current sub-panel connection to the new main panelboad, but he's against it. He feels that since he's going to pull out all of the breakers in the sub-panel and use it as a j-box, he won't need to ground it. There is currently a rsg conduit from the main panel to the sub-panel and I think the rule is to keep a ground connection, if one existed originally.
Another issue deals with installation of a ground bar, for an existing structure which qualifies for a MAKE ground. The NEC 99 mentions that a two square foot metal plate can be used as long as it's buried two and a half feet down. That would be far easier to install than an eight foot pipe. However the local electricians don't even consider that as an option.
The other question is about the sizing of the new ground connection wire with the new main panelboard.
A local electrician claims that if 4 awg wire is used, it can remain bare throughout its routing. However a 6 awg must remain insulated. It got a different impression from the NEC. Any suggestions?

 

[meihm]

STEPE:
1. Regarding the existing ground at the existing panel, soon to be a junction box:

A. The existing service ground must be lifted at this location. If you keep the existing earth ground and make another (proper earth ground at the main servic equipment, you wll have providedmultiple paths to ground for the neutral (grounded) conductor, which is prohibited by the NEC/CEC.
B. Yes, the junction box must be grounded. The 1996 NEC/1998 CEC states:
"250-33. Other Conductor Enclosures and Raceways.
Metal enclosures and raceways for other than service conductors shall be grounded."
C. If there is a rigid galvanized conduit between the exising panel enclosure/junction box and the new service panel enclosure, and IF the ground path is preserved, that is all that is required to ground the panel enclosure/junction box.

2. Regarding the Ground electrode:
A. The ultimate authority is the local building department, or Authority Having Jurisdiction (AHJ). You really must check withthem since local interpretations vary from locale to locale.
B. The main grounding electrode, if available, is a metallc cold water pipe having 10 eet or more contact with the soil. Many jurisdictions require an additional or auxiliary ground electrode, such as Ufer ground.
C. If these are not available, or not feasible, then "made" electrodes MAY be acceptable to the AHJ. In addition to plate elctrodes, other possible solutions include ground grids, ground rod(s), chemically enhanced ground rods (e.g. XIT rod), Bare wire in the service trench, etc, etc, etc.

The local electricians may know something you don't, such as the attitude of the AHJ, extreme soil corrosivity, etc.

Discuss this with your local inspector.

3. Regarding your last comment, the closest NEC/CEC language is:

"250-92. Installation.
Grounding conductors shall be installed as specified in (a), (b), and (c) below.
(a) Grounding Electrode Conductor. A grounding electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried. A No. 4, copper or aluminum, or larger conductor shall be protected if exposed to severe physical damage. A No. 6 grounding conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection where it is securely fastened to the construction; otherwise, it shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor. Grounding conductors smaller than No. 6 shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor."

As a professional engineer, you surely recognize superior authority. Stop listening to electricians, especially if you don't like their answers; take your questions to the people who will make the decisions regarding your installation. These same folks (the AHJ/building inspector/electrical inspector) can make your life easier with a little advance discussion, or make your life a living hell-until you meet their interpretations of the applicable codes, including the local additons to the NEC/CEC.

meihm

 

[STEPE]

Thank YOU, Meihm, for reinforcing my thoughts and conjecture on this situation.