Older Breaker Box

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  #1  
Old 07-26-07, 11:47 AM
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Older Breaker Box

I have an older breaker box, probably installed circa 1962-64. It has no main disconnect --- instead, some two pole breakers feed other parts of the box where single pole breakers provide power to individual circuits.


I've yanked out the electric water heater and range, and the furnace is gas. So capacity isn't an issue for my use of this box.this box.


Any reason I couldn't expect to use this box indefinitely? I see no evidence of anydeterioration of the wire insulation.


However, I would like to upgrade some of the older wiring with no grounding wire, and otherwise upgrade the circuits to current standards.

My preference would be to start that by installing a sub panel near the kitchen to use in rewiring the kitchen. I'm concerned that the inspectors are going to want me to start by replacing the breaker box.


Any comments would be welcome.




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  #2  
Old 07-26-07, 02:22 PM
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> some two pole breakers feed other parts of the box

This is called a "split-bus" panel, and the design is considered obsolete. There are up to six 2-pole breakers which collectively serve as the main breaker. This design is no longer used, because it provides only a single layer of breaker protection to appliances like the range which are served from the live portion of the panel. In a modern panel, both the range breaker and the MAIN breaker would have to fail on before you could have unlimited current to the appliance; with the split bus panel, only one breaker needs to fail before the range is supplied with unlimited current. Be sure to mention you have a split-bus panel if you're asking for future advice.

> Any reason I couldn't expect to use this box indefinitely?

As long as you can get breakers which are listed or classified for use in the panel and the buses remain in good condition. This will become a problem when installing bedroom circuits, for example. Modern code requires AFCI breakers which are typically not available for old panels. Another example would be a spa which requires a 2-pole GFCI breaker which may not be available. You may need to add a modern subpanel (or replace the service) to accommodate AFCI or GFCI breakers. Furthermore, what is the amperage of your existing service: 60, 100, 150? Your electrical needs may outgrow the existing service which would then require an upgrade.

What is the manufacturer of the panel? If it is Federal Pacific (FPE) Stab-lok, then it should be replaced ASAP.

> I'm concerned that the inspectors are going to want me to start by
> replacing the breaker box.

Unless there is some very obvious safety hazard in the panel like arcing, the inspectors will allow you to use your old panel provided you can install the correct breakers in it.
 
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Old 07-26-07, 09:58 PM
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The Split Bus Panel is a Square D "QO" Load Center

Thank you kindly Ben for your comments.


This box is a Square D "QO" Load Center, so I've slipped the Zinsco problems. I Googled "split bus breaker box" to read up on what I have and found loads of problems with Zinsco, as you suggested.


I just retired as a furnace repairman selling off my repair business to a new man Memorial Day. I was once employed with a gas utility and self employed doing repairs on gas equipment and furnaces in recent years, and I have an Advanced Class Amateur Radio license.

Liike a lot of contractors, my own home tended to be neglected while I worked on everyone elses. I still enjoy doing home repairs and improvements, and one of the activities I have planned for retirement is doing the repairs and upgrades to my home and rental property that will put them in the pink.

I figure doing the new sub panel and rewiring the kitchen to the current code would be a good first electrical project, allowing me to go through the permitting and inspection process and see how my work appeals to the inspectors. If that goes OK, then I'd undertake additional projects until the wiring for the whole house is updated.

Because I've converted the range and water heater to gas, and the furnace is gas, there isn't a large electrical load in the house. One bedroom has electric baseboard for heating and a medium sized wall mounted AC on one 220 circuit (rated 10 amps), and I have a 2.5 HP air compressor wired in on another 220 circuit, but there isn't a lot beyond lighting and wall outlets other than that stuff.


I'm guessing that the incoming conductors are probably for 125 amps. When I get around to replacing the main panel, my bias would be to keep that same capacity in the new box rather than going to 200 amps. Any comments on that?

Is an inspector likely to accept replacing the panel but keeping the existing conductor and meter box that feeds it? That's one of the things I'd chat with an inspector about when I'm getting an earlier job checked out, but perhaps you can give me a general impression.

The electric utility replaced their portion of the conductors to the house a few years ago when one failed ---- I could understand that leaving forty year old conductors in place with a new box may be a poor practice.


Anyway, my aim is to learn some new skills, upgrade my house and enjoy the process.

I spent several hours today in the crawl space of my rental house, doing things like rehanging insulation in the joists that had fallen down. Crawl spaces are not one of my favorite places to be! Tomorrow I get to go back and remove the dried out dead cat I found, along with the skull of some other dead animal. Retirement is fun!


Anyway, thanks for the help. This is a great discussion board and I spent two or three hours reading through recent posts last night, and expect to read through a lot more old posts in the future. There is a world of practical electrician's wisdom and references to book learning in those posts, a particularly powerful combination.



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  #4  
Old 07-26-07, 10:32 PM
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One possible downside to increasing the service amperage is that many years ago Seattle passed a law that any increase in an electrical service size would require increases in the insulation and other "energy saving" improvements to a home's envelope.

This was done when so many people were converting to electric heat (at the time Seattle City Light had among the lowest electric rates in the country) and the politicians were concerned that the load increases would require SCL to increase their generating capacity or the amount of power that was purchased.

Of course no one is converting to electric heat these days so such a fear is unfounded. I do not know if this law/requirement is still in effect.
 
  #5  
Old 07-27-07, 06:30 AM
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> This box is a Square D "QO" Load Center

As far as I know old Q0 panels are still okay for use.

> my bias would be to keep that same capacity in the new box
> rather than going to 200 amps. Any comments on that?

That's a common practice called panel changeout instead of service upgrade. In some cases you don't even need to replace the metal box, just the "guts" of the panel.

> Is an inspector likely to accept replacing the panel but keeping the existing
> conductor and meter box that feeds it?

Yes, but you may need to do a demand load calculation to prove that your existing 100 or 125A service is adequate for your current needs. This is standard calculation defined in the code for determining the service size for a home. The only problem you may run into is if your existing service is only 60A; code now requires minimum 100A.
 
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