Did I just cook my preamp?

@obarrett 

https://youtube.com/shorts/t1jazBAT3M4?si=uweJOKoK0xRxrYDH

In your video, when you measured for voltage from the receptacle ground contact to the heat radiator the test probe connection to the receptacle ground contact was poor. The 120Vac reading was not a solid contact connection.

You should have used the OEM power cord ground. Insert the mm probe into the center ground contact. That also frees up your hand and you can focus your eyes on the probe connection to the radiator valve and the meter.

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WARNING: I hope you saved the plastic outlet cover plate you removed from the receptacle. When you remove the 2 to 6 outlet extender everything metal you see is HOT 120Vac to anything grounded. Don’t put your body between them.

** EDIT: On second thought. Don’t remove this one. Just leave it be.

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Also in case you haven’t thought of it. You are going to have to move the speakers and audio equipment out of area the electrician will be working. Take some pictures first of the equipment where it normally is sitting. Just in case he asks.

The Electrician needs a minimum of 3ft working space in front of the wall outlets. The more the better. A happy Electrician is a productive Electrician.

Did you watch this video?   Reverse Polarity Bootleg Ground Testing 

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Yes, I watched the video. I should get one of those no contact voltimeters, they’re $10 and apparently can detect a hot ground.

some photos from today

P.S. it’s hard to make good contact with the radiator ground. The conducting part is only a small little band in the knob. That’s why the reading is unstable in the video.

Old rubber cloth covered insulated copper wire. This is why I advise a non electrician do not pull an outlet out of a wall or ceiling box in a really old apartment building, or an old house. 

The building Landlord has mess. An expensive mess. And more than likely the whole building’s wiring is in the same shape. 

Just a guess the electrician didn’t find a bootleg ground jumper wire on the neutral contact side terminal screw to equipment ground terminal screw on the Hot / neutral reversed polarity outlet. (outlet 1.)

I doubt he found a jumper on any of the outlets. The rubber/cloth insulation deteriorated over the years causing the bared copper wire to contact the wire support bracket. There was a 50/50 chance whether the Hot wire or the neutral wire faulted to the steel bracket / box. It’s kind of amazing that both didn’t fault to the box. Dead short.

Neutral fault to the box it’s an earth grounded box. Hot fault to box, a HOT 120Vac to ground box.

The odds are good that there are other outlets in the apartment the electrical wiring is in the same condition

Did the electrician say what type of branch circuit wiring it is? It could be BX steel armored cable. It probably comes through a hole in the back of the box and the clamp holds it in place. In the third picture I thing I can see the cut end of the armor.

 I see brick on walls in your photos. Just a guess the building is constructed of brick. ???

Did the electrician say what wiring method he will use to rewire the apartment? The only thing I can see is install surface mount Wiremold.

Wiremold steel raceway. 500 / 700 series   Start on page 47.  

I’m really curious, find out who manufactured the electrical panel that feeds your apartment. 

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@obarrett 

Correction: Edit:

Did the electrician say what type of branch circuit wiring it is? It could be BX steel armored cable. It probably comes through a hole in the back of the box and the clamp holds it in place. In the third photo I think I can see the cut end of the armor.

I looked again at the photos this morning. I am not sure that is the end of a steel armored BX cable. The empty hole in the clamp beside the one with the wires  appears to have a raised ring as well.

Also I do not think the conductors enter from the back of the box. The empty hole in the clamp shows the back of the box solid, no hole, or knock out.

I think the wiring could be old, really old, cloth covered NM cable with rubber/cloth insulation. The cable enters the box from the bottom.

What type of old wiring did the electrician say it is?

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