Manche757

Only circuit 1 should be on. Did you turn others on and 1 off?

Turn on heat and see if it comes on. I assume you have a gas furnace with electrical controls

In that same circuit, one box has just one cable with black and white? The other two boxes have two cables of black and white? No other wires?

No lights, fans ect, worked with just that breaker on?

Nothing that you know of was hard wired in circuit 1?

You probably have outlets in more than one room for circuits. That is so if one trips you don't lose all power in that room. The next step is to find that out. Turn off all breakers except 1. Go with your tester to other rooms and test hot slot to neutral slot to find others on circuit 1

You many have more than one circuit leaking hot to ground but you have made progress. Circuit 1 looks like the most corrupted. Is that the one that the dishwasher is hooked to?

That's quite a picture. Is that light hooked to two switches? Do you have more than two switches for any light in your house? If so, you would have 2 way and 4 way switches for that light.

Turn off all breakers. Test 1 alone. Turn it off Test 2

I tried to read the amp rating on 220 circuits but could not get them to come in clearly. One looks to be 20 amp. That might have been for a window air conditioner. Look for a 220v outlet by a window. The disconnected cable in lower right panel has a red conductor, a second hot. It also has the same insulation the stove circuit does. It may be the original stove circuit. Your house may originally have had separate oven and cooktop burners. That can be considered later; still in discovery mode for now.

When you are home and have time, turn off all breakers. Test from kitchen outlet box to the same water pipe you used before. Should get no power. Then turn on one breaker at a time and retest at same box to water pipe. If no power, leave breaker on and turn on next breaker. Continue on. If you get power at any time, turn off that breaker and test rest of breakers. Hopefully, this will isolate the problem circuit(s).

Ok. We do not have to worry about losing the prime on an above ground water pump that might have a leaking check valve, if power is turned off. Also you have already determed that your kitchen water pipe has continuity to ground. Copper pipe connected to metal city water main is assumed. Ground to cold water pipe used to be allowed until nonmetallic water pipe came along. No air condition circuits?

From what I can see of your panel, there are 4 220v circuits. Stove at top right? Shop lower left. What other two for? Are you on city water or well? Electric or gas water heater?

From the pic you sent, the neutral and grounding bars look to be connected. Are you back home?

Got time for a quick test? Turn off breaker to a bedroom that does not have known ground. Test an outlet hot to neutral slot. And box to neutral slot

Did you locate what the other ends of the two white wires were hooked to?

You do not have that many grounded boxes/outlets. Depending on how much more you are willing to do, I would suggest you go back to the kitchen

Chances are the problem did not exist when an electrician put in the new panel. You might want to look at changes that were made with after that. A next place to start would be in the kitchen

The results that I would expect normally would be hot to box or center screw: 120 with ground at box. zero or near without ground. Hypothesis: Current was passing to ground at kitchen locations before you started your back splash project.. So long as you did not remove covers and touch box and ground to something else you touch in the kitchen, you were not shocked or aware of it. When wet mortar came in contact with the box and at the same time you touched something that grounded you (in this case the stove), you felt a shock. Solution tried: isolate where the boxes are being energized and correct the feedback. So far the point of current to box has not been found

test hot to box while you are there

Do the test again on various outlet. Hot slot and metal in middle

Are you comfortable going to your main panel in your house and pulling away all 3 leads that go to the shop? Temporary.

In 1969 you most likely had a regular 3 prong outlet that was grounded to the electrical panel. Washer and refrigerators had 3 prongs usually at that time.

Man, let's all gather around at your house with a case of beer,

First off let me back track a little in a 220 circuit. Some appliances use both 110-120 /220-240. An electric clothes dryers might use 220 how the heating coils but 110-120 for timers and the motor that turns the drum. In that case, whether you call the third wire a ground or a neutral becomes pedantic. If the circuit runs all the way to the electric panel, it becomes a non-issue.