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Old 05-29-2012, 12:18 AM   #1
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New Home: 2 Prong Outlets & K&T Wiring (Maybe)

My girlfriend and I are in the process of buying our first house and have possibly found one. Everything looks great (original woodwork has been preserved) except I have some questions regarding the wiring.

The house is a 2000 sq ft, 2.5 (3) story built in 1924. All of the receptacles in the home are 2 prong that are installed in the baseboards, with the exception of 2 outside receptacles (grounded, GFCI, under covers), and ungrounded GFCIs installed in the bathrooms & kitchen. There is also a 3 prong outlet near the breaker box that may or may not be grounded (can't remember). The house drop and breaker panel were updated last month to 200amp service.

When I saw the 2 prong outlets, I was worried that the house may have knob & tube wiring so I took a look under the house in the crawlspace. Without going completely under the house I could see the porcelain insulators and wiring running from them up and into the house. I don't know if this wiring is still in tact or if it has been disconnected and left there. There are 3 outlets per bedroom, which from what I've read didn't really happen with K&T.

Also, upon investigating the breaker panel, I noticed a single, 20amp breaker labeled "Upstairs Lights/Outlets". A quick assessment of the upstairs found: 9 outlets in bedrooms (3 per), 3 outlets in third floor (one of which for a window unit A/C), 7 ceiling light fixtures, 2 sconce lights by bathroom mirror, bathroom exhaust fan, 1 GFCI in the bath, and possibly 1 outlet in the upstairs hallway. All of these are connected to the same 20amp breaker.

There is a 60amp double breaker running to the old fuse subpanel in the workshop, a 40amp (I believe) double breaker for the stove, and 2 single 15amp breakers (both labeled A/C) for the central A/C unit. There are 2 20amp single breakers for the "Downstairs Outlets/Lights", a 20amp breaker for the "Outside Outlets", and a few others that escape my memory right now.

Sorry for the extra long post. I have been lurking for months while we are on the house hunt, and wanted to gather some advice/info from the decades (if not centuries) of experience on this forum before we decide what to do.

My questions are:
1. Is there an easy way to determine if the K&T is still in use?
2. Any ballpark figures on the $$ needed to rewire the house to add a ground?
3. Is it normal to have so many outlets on one 20amp breaker?
4. Are the 2 single 15 amp breakers for the A/C ok, or should that be 1 30amp double breaker?

Thank you in advance for any and all help you can provide. I appreciate it.

Future Home-Owner and DIYer


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Old 05-29-2012, 05:47 AM   #2
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Take the covers off of a few switches and receptacles and poke a flashlight inside to see if the incoming wires are from cables, a tiny amount of sheath or jacket showing (probably reasonably modern) or entering the box individually (probably knob and tube). Wires entering the box two through the same hole and therefore next to each other can still be knob and tube. An experienced home inspector should definitely be involved.

Some insurance companies will not insure homes with any active K&T wiring. So it is highly desirable to find this out in advance and perhaps not buy the house. Just getting an extra price concession from the seller is often not good enough because upgrading the K&T wiring then becomes a rush job, which you would not be able to do yourself, would not allow you to do even peripheral work such as opening up the wall yourself, would likely cost more than you expect, and worst of all be a major anxiety in the month after closing. (A price concession should take into account all four of the immediately preceding.)

In the U.S. there is no arbitrary limit on the number of receptacles a given branch circuit may have.

Fourteen gauge wiring, K&T or otherwise, may not be supplied by a 20 amp breaker; must be 15 amp.

If the air conditioner is fed by two 15 amp breakers, it would be better to have a 15 amp 240 volt rated double wide double breaker of a nature which, if one side trips, both side are forced off.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 05-29-2012 at 09:52 AM.
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Old 05-29-2012, 06:07 AM   #3
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You really need a home inspector to do a full report on this house. One you hire not one the realitor suggests.

Things I'd be looking at is the roof, plumbing and the wiring.

A home that old most likly will have old galv. or steel supply lines and cast iron drains, which at some point will all leak and close up from the inside out.

That's great the panel and main power line where up graded, but does nothing if all the other wires were not also replaced.
It's common to see a 3 prong outlet with propper ground installed near a new panel so there's an avalible outlet to use while the power is off to the rest of the house while it's being rewired.

Just because you see a 3 prong outlet or a GFI does not mean it's grounded.
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Old 05-29-2012, 07:50 AM   #4
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As yesterdays electrcial needs were less the circuits typically covered a larger area.

You can look near the panel for single conductors run either into the panel or nearby junction boxes. If metal boxes wer used there should be a slot cut between the two knockouts where the single conductors enter the box.

Instead of adding a ground I would look at adding new circuits or a rewire. This way the circuits are grounded and the circuitry will be up to todays standards. You will also be able to insulate once the K&T is gone.
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
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Old 05-29-2012, 07:56 AM   #5
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Call a local electrician in addition to a home inspector. He MIGHT be willing to give you a free quote on rewiring the house. That way, you can use the price quote to negotiate a lower price.
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