Back To Square One: Updating House Electricals.

Factual Questions
1

Okay, in this thread I talk about upgrading my outlets and installing a new sub breaker box in order to accomodate some electrical goodies that I plan on putting into a room that I am rebuilding inside my house. I have a blank slate as far as this room is concerned. Hell, I barely have walls. But atleast I have the freedom to mold the room into exactly what I want it to be. My evil high tech lair.

It wasn’t long into the thread before I realized my achilles tendon: the old wiring. It is now apparent to me that I have to take a couple steps back before I do anything else.

Little background. My house was built in 1895. It is as sturdy as Fort Knox. The foundation at the base is something like 38 inches wide. Some plumbing and asbestos problems (removed) withstanding, we got a good deal on it. The only problem is that the wife and I are starting from the ground as far as rebuilding the inside. Very little, excluding the walls, but including the beautiful woodwork, is salvageable. Oh joy. But it’s a labor of love, definitely. I finally have a hobby. I don’t have hot water, but I atleast have a hobby.

The original wiring is Knob And Tube. How do I know this? Because some of the knobs are still bolted to the rafters in the basement. But sometime before the 1960s, the wiring was upgraded to two conductor, no ground, PVC wire. That is what I have in my house right now.

I plan on a lot of nice upgrades: recessed lighting, brand new grounded outlets, you know, the works. From what I understand, this type of wiring is grandfathered in under all of the new building and safety codes. I’ll be sure to tell that to my wife as we’re fleeing our bonfire of a house at 2 am. Really, Honey, it’s okay.

One bonus. Before we moved in, we had a brand new 200 amp breaker box installed in the basement. Unfortunately, it is the only grounded electrical item in the house. All of the wires coming out of it are two conductor.

Tearing into what existing walls we have is not a problem. The problem is that I have seen first hand some of the wiring in this house, and it resembles a spider web. I can isolate individual branches and maybe update them one by one. But as soon as I go one level deeper than that, it is apparent that the whole system will need to be replaced all at the same time. This is something that I neither have the time nor the money to accomplish, atleast in its entirety by the Spring. Plus it is out of the question to shut the power off to the house for more than a couple hours at a time.

My questions:

[ul]
[li]Exactly how dangerous is this two conductor, no ground, wiring?[/li][li]What must I replace?[/li][li]Would an extension of an existing wiring system, using new wires, still fall within the safety standard?[/li][li]How do you ground a three prong outlet with only two wires?[/li][/ul]

2

How do you ground a 3-prong outlet with only two wires? YOU DON’T. Not properly anyway. And if you’re not gonna do it properly you might as well leave the 2-prong outlets in there and cut of the grounding plug from your appliances. (You wouldn’t do THAT, would you? Ok you might, based on what I’m reading here.)

Really, wire is cheap. VERY cheap. Tape new romex to the old wire, pull it thru. Done. Only one small run at a time. You don’t have to do the entire circuit at a time, since you said you don’t have tons of time on your hands. Yeah you have to shut off that circuit while you’re doing your 20 mins of work, but so what? The key here is as long as you start from the breaker, properly connecting that bare ground conductor at each junction, when you get done with the entire circuit it’ll be proper. No reason your family has to be inconvenienced for days/weeks at a time.

Money is simply not an issue, when it comes to 3-conductor romex vs. whatever you have in there now. What is it, $15-20 a box? What’s your life worth? If you say less than $20, well I got a life insurance policy here I’d like you to sign. I’ll even pay ya $20 for your time. :wink:

But seriously, just do it right. To be honest I think you should be consulting some more professional resources at this point than a message board. I don’t mean you have to hire an electrician (you probably should), but at least read over some books on the subject. As I said above it won’t take that much longer to just do it right. Especially since you can destroy some walls.

In the other tread someone suggested running a pipe upstairs. That’s damn good advice. Even better though, I’d recommend running empty conduit to EVERY room while you have a chance, and leave a nylon string from junction to junction. That way when you need to run more low-voltage wire you just tie it onto the string and pull it thru… then pull the string back into place via similar means and leave it for next time. Much easier than fishing wire.

Oh, and you ARE running CAT-5 and multi-conductor wire (for intercoms, phone systems, etc) to every room too, right? :wink:

3

The wiring itself is not dangerous. It’s only a problem when you have an appliance that requires an earth ground. (This is not 100% true, as there is value to grounding the metallic junction boxes and conduit.) As I stated in your other thread, there is a “loophole” in the NEC that says you’re allowed to install a GFCI outlet (which has three prongs) in lieu of running a ground wire. (I did this in our previous home.) But there are disadvantages to doing this, namely 1) GFCI’s can fail. You should test them at least once per month. 2) Some equipment actually requires an earth ground to be present to even operate. Florescent shop lights and surge protectors come to mind.

I don’t know; you’ll have to get with an electrician on that.

There are no fabulous secrets I can share with you on this one. The only way is to run a ground wire. Or install a GFCI as described above.