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Grandparents' Basement Wiring BEFORE I Rewired It

Grandparents' Basement Wiring BEFORE I Rewired It

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Here's a simplified diagram of the old electrical layout of just that one circuit, which controlled all the lights, all the outlets, and the entire garage. I will post an AFTER diagram soon.

Note now the BX cable just curved across the ceiling (nothing wrong with that since it was notched into the joists and secured properly) but it was just spliced to the K&T wiring with no junction box with tape and tar. The K&T wiring, while just a short run of less than 10ft, was missing chunks of insulation and was a major shock hazard. The pull chain light at the end of the K&T run had no junction box (not really surprising considering it's K&T).

Most of the wiring was done with the cable represented in black. Some issues I had with that was that the outer jacket was frayed in parts and looked like it was patched with some sort of glue years ago. And somehow the insulation on the neutral had split lengthwise around the conductor, leaving a bare neutral. Fortunately everything was polarized, even the K&T.

Everything you see here is gone except for the runs represented in white. The blue and red boxes were retained as well.

022016_002.jpg 022016_003.jpg Meme___Pepe_Basement_Lighting.png 021516_006.jpg

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Date added:Feb 15, 2016
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Ash
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Feb 16, 2016 at 10:49 AM Author: Ash
What about the run from the basement to the garage ? You could replace it all or there is part underground etc that you cannot reach ?
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Feb 16, 2016 at 11:27 AM Author: streetlight98
The run toward the garage up until the blue box at the top of the diagram is all I replaced. I simply disconnected and removed the BX cable and ran a new 14/2 NM cable along the main support beam of the house (shown by the dotted line down the middle of the diagram; it's a solid wood beam about 6" X 6". Modern houses just use three 2X6 planks sandwiched together).

Once you get to that blue box, there was rigid metal conduit going down into the foundation at an angle and there was two stranded single conductors with gummy-feeling insulation on them. I didn't replace the underground feed since there has never been an issue with it. It's clear that the cable used is not suitable for direct bury so I assume the conduit continues for the whole buried length (about 10ft) to the garage. In the garage, the same looking pipe comes up out of the ground and then the people who rewired the garage picked up from there. I bonded the ground wire of the new NM cable I ran to the box and did the same in the garage (since the people who rewired the garage didn't connect the ground to anything). Although there is no equipment ground running through the conduit, I don't think it's necessary since the rigid steel conduit has the grounds bonded to it (so basically using the conduit as the ground) and since the conduit is buried, it's technically grounded on its own. There have never been any shock incidents in the past 50 years so I'd say it's OK.

I will make a diagram showing the new wiring layout next week. I haven't finished wiring the part of the basement represented by the top half of this diagram yet. Right now, the bottom half of the diagram is all finished with the four troffers. For the top half, we installed the fixtures but have not wired them in yet. I have to figure out the best way to hook them up with the least amount of wire. I don't want to disturb what I've already done since those connections were a real PITA to make since 12 gauge cable is hard to connect together with wirenuts when you're talking about three or four wires together.

Please check out my newly-updated website! McCann Lighting Company is where my street light collection is displayed in detail.

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Feb 16, 2016 at 11:56 AM Author: Ash
I dont think it is good thing to use that as PE. In case of short Phase to Earth in the garage, the return path is thrugh that pipe. Who knows how good its continuity is. If the short circuit curent will be less than 150A..300A, the breaker won't trip immediately. If it is less than ~20A (on 15A breaker) it may heat up for as long as hours

In that time you may have potential difference between the metal box and structure, and even some big arcing in the spots where a less than acceptable contact is

If it is the same pipe, you might be able to pull in new cable - See if the old moves freely when somebody gives it a tug from the other side
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Feb 16, 2016 at 12:52 PM Author: streetlight98
What if I was to install a grounding rod in the garage? Or would that cause issues because the ground wouldn't be tied in with the common at the breaker?

Please check out my newly-updated website! McCann Lighting Company is where my street light collection is displayed in detail.

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Feb 16, 2016 at 03:22 PM Author: Ash
That would be an option, to supply Phase/Neutralfrom the home and Earth locally. Then the local Earth is only ever connected to metal stuff that needs Earthing - the Neutral is completely separated from it

This system is called T-T (localised Earth at the premises, not connected to upstream Earth) and is common in older installations in Europe, and works well. It is pretty safe, with the following BUTs :

1. There may be a few volts difference between the local Earth and the Neutral. As long as you keep them separated and use each correctly, this is not a problem

2. If upstream Neutral is disconnected, Neutral conductors (so screw shells of lamps, ...) become at full line voltage. Since in normal use you dont touch stuff connected to Neutral, this is not a shock hazard except when you go and mess with stuff

3. For a time when you do mess with stuff, it is good idea to cut both Phase and Neutral to the circuit, and this way avoid the problem in 2. A double pole breaker (Phase and Neutral) will sort out the problem

4. What about overcurrent from Neutral to Earth ? There are 2 pole breakers where the Phase pole is a breaker and Neutral pole is a switch (so, overcurrent on Phase will disconnect both, overcurrent on Neutral won't trip anythig at all), and there are 2 pole breakers which are really 2 pole breakers. The latter will trip in case of shorts between Neutral and Earth that pull high current for whatever reason

GFCI breaker for this entire circuit in the panel will address Neutral currents too, though reading the other discussion i understand you dont have Magnetic GFCIs readily available over there, and i trust them much better than the Electronic



And finally, i dont know if T-T especially T-T part in a bigger TN-C system is allowed in the US

(TN-C means one Grounded conductor, which acts as a Neutral. This basically means the messenger wire of the service drop. The Grounded conductor comes up to the Neutral bar in the panel, and only in the final branch circuits Earth and Neutral are separate. This is the normal way how panels are wired in the US. In Europe nowadays the common variation is TN-CS, where the Grounded conductor splits into Earth and Neutral before the Neutral bar and not on the Neutral bar itself)
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