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Wiring in 80+ yo house

Posted by grandmum (My Page) on
Fri, Apr 19, 13 at 7:42

Daughter is considering buying a 80+ year old home. Was told the wiring was upgraded 25 years ago. While deciding to place an offer on the property, what can she do herself prior to an inspection to insure that indeed it was modernized? How would you approach such situation and what questions would you ask?

I ask here since I am impressed by the knowledge presented by many of the regular forum members.


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RE: Wiring in 80+ yo house

Her best bet would be to make the offer contingent on a professional inspection and find an inspector (and this is going to be the hard part) that has a clue about older electrical systems.

At 80 years (depending on where you are), you are in the end of the knob and tube era.

1. Check the main panel. At 25 years ago, it probably should have been replaced with one with breakers. Is this now the service disconnect? Is the panel one of the few from the era that are known to be problematic (FPE, etc..)
Was the service properly upgraded with the panel change?

2. Are there any vestiges of the old fused main service left. Are the energized?

3. What is the nature of the redone wiring (look at the cable jackets coming out of the new panel). Most likely it is NM. Are there is any older BX or connections to K&T?
Any aluminum on the smaller branch circuits?

4. Poke around in the basement and attic. Are there any K&T left that isn't assuredly deenergized.

5. Are there grounded (three prong receptacles). Are the ones present properly grounded.

6. Where the kitchen and bathroom circuits brought up to a more modern code or at least GFCI's installed where appropriate.


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RE: Wiring in 80+ yo house

The best answer is inspection of the main breaker box.

First, bare copper quarter inch wires must connect from the box to cold water pipes (where that pipe enters the building), and to an earth ground rod just outside.

Second, the breaker box must be circuit breakers - no fuses.

Third, wires to the breaker box would be three wire type. Typically Romex wires, colored white (back then), and similar to what is viewed in Home Depot, Lowes, etc. That cable must contain three wires. Otherwise wall receptacles cannot be three prong type.

Fourth, in most jurisdictions, a breaker box may have an inspection sticker dated by the electrical inspector.


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RE: Wiring in 80+ yo house

"First, bare copper quarter inch wires must connect from the box to cold water pipes (where that pipe enters the building), and to an earth ground rod just outside. "

This may not actually have been a code requirement at that location 80 years ago.

If the panel has been upgraded to breakers, a single bond to the cold water pipe may be all that is required.

A pair of grounding electrodes is actually a relatively new requirement and wiring (with a very few exceptions) is only REQUIRED to meet the code in effect when they are installed.

Upgrades must meet the code in affect when that work was performed, but you are still not required to tear your house apart every three years when the next code revision occurs.

Grandfathering allows the continued use of even old systems (like knob & tube) that are in good condition.

This post was edited by brickeyee on Sun, Apr 21, 13 at 13:40


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reRE: Wiring in 80+ yo house

Get an actual electrician to inspect the wiring.

Very few 'home inspectors' now what they are actually looking at and the eledctrical code that was in effect at any particular time (letalone the most recetn code in effect now for NEW work).

Some electricians have no idea also (often the younger ones who do only 'production' type new work).

You need a real old fart that has been around through a lot of code revisions ad can recognize correctly executed old work.

Grounding requirements for general use branch circuits did not arrive until the 1950s.


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RE: Wiring in 80+ yo house

Without a friendly reference or "knowing a guy" how should she approach finding an electrician (in addition to the all-around home inspection).

Roll the dice and call a contractor and hope they send someone compentent out or maybe contact the city's electrical inspector/ code inforcer or what??

BTW: Unexperienced Father saw that the panel is 100 amp GE breakers, no date of installation. Did not open panel. Wiring in attic and basement enclosed in metal conduit and examination of a few outlets said it was grounded with his tester. No wiring in cloth or not in conduit viewed anwhere on general look in basement and attic. There was no evidence of old fuse box or wiring. Of course we cant see what is in the walls.


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RE: Wiring in 80+ yo house

add to above post:

I mention 2 options to my daughter and we are concerned:

If we call a contractor to inspect the wiring we fear he might be influenced by turning it into a chance to garner an upgrade/business.

or if we call the City's inspector, would we be opening up a can of worms in some other way?


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RE: Wiring in 80+ yo house

By any chance, are you Chicago? I think that's where everything has to be in conduit.

I can't actually give you any help, but I was just wondering if there is a reason that you suspect that the wiring wasn't updated properly? Or is this just due diligence?

If there isn't any particular reason for you to be suspicious, then based on what you've observed, I would assume everything was done properly and move on to other issues. It has obviously been updated since the house was built and since it's all in conduit it probably means that a licensed electrician did it.

I'm sure others will jump in here and still insist that you get a proper electrical inspection, and there's nothing wrong with that if it will put your mind at ease, but I personally wouldn't bother.

To each his own.


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RE: Wiring in 80+ yo house

Yes I am in the Chicago suburbs greg and this is indeed due dillegence. There is no reason we are suspicious other than the age of the home.


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