Whilst trying to lighten the load of certain breakers, I tapped into an existing line and installed a junction. But there was little slack in the existing line. I got all three wire connected and with wire nuts, but it was very tight.
Now wife tells me that power is out, but no breaker tripped. I'm assuming that the connections have come loose. (I'm at work)
Any tips on how to remedy other than running a longer line, or having next door neighbor junctions?

 

Any splice requires 6"-8" of wire. The best practice is to use two junction boxes about 12"-15" apart then run new cable between the two junction boxes so you have 6"-8" of wire to connect in each box. Note: the boxes must be permanently accessible.

Second beast is to replace one of the cut cables with a new longer cable from its point of origin.

 

I opened the junction to find this - sorry its blurry, but the nut connecting the neutral is partially melted. It hadn’t come undone, which was my theory. Why did the neutral short? Why not the hot? And why didn’t the breaker trip? It’s a 20A running a 12 gauge line. The reason I used 20 was i have a countertop convection oven on that line. It sucks some juice.

I did find a junction box in the basement ceiling. Wife doesn’t like the hole i made, but hey…

Was that a typo, or a hint?!

 

The current used in a circuit is the same on the white and black wire. The white connection melted because it was poorly made. Either the copper part of the wiring was too short or the wirenut was loose. It didn't trip the breaker as it wasn't a short. That connection could be burned enough to be open.

This is one reason why I prefer to twist my connections and use the wirenut as a cover.

 

Loose connections have excessive resistance. Current flowing and encountering resistance results in heat. You are lucky if the loose ends spring apart or melt so as to leave a gap large enough to stop the current flow, before starting a fire.

In a few cases jumper wires (pigtails) can be used to join too-short wires inside one junction box to avoid having to have two junction boxes with a length of cable in between. Usually soldering of the wires (first coil up one wire end and slip that over the other wire end) is needed.

Now, too tight could have been a problem in a completely different scenario. Two wires stretched tight as violin strings, touching each other in the middle (in a conduit otherwise they would be defined as knob & tube), and over the years as trucks rumbled by outside, the wires "twanged" and cut each other's insulation where they touched and a short circuit occurred.

Short circuit -- A "path of least resistance" (both literally and figuratively) formed when wires or metal parts touch that should not touch and the typical result is that a light or other device that should be energized is not and/or abnormally large amounts of current flow.

 

Why are there bare wires in the box? Maybe just my poor eyesight but looks like the blacks fell out of the wirenut. If not ....never mind.LOL

 

You may have seen the ground wires. None of the nuts came loose.

This morning, the power to the entire house flashed for about 5 seconds. Off then back on. They are doing road work the next street over, but I didn't see any active work an hour later. Is there anything that would make this happen without tripping any breakers? Or am I just getting paranoid from one mis-connection?

 

Breakers will trip on overload or a direct short. Did either of those occur?

 

No. But is there anything that would make the power shut off like that?

 

It does not look like the box is properly grounded and the cables are too short to be secured as required.

 

I have remedied the shortness, by adding another junction just 12" away with plenty of slack so there's no tension. Also pre-twisted all the wire together and trimmed the ends, placed caps, taped them off...

I've just received a txt from my wife - it seems the lights on the hood vent are flickering and buzzing. They are cfl's if that matters. I'll have to check when I get home, but when I moved one branch of an overloaded breaker to another (near)empty circuit, it is now occurring to me that I may have connected 12-2 to old 14-2. what effects will this have?

 

None of the old metal junction boxes are grounded in this house. Excuse the ignorance, but do the metal boxes need to be grounded as well as the wires inside? So I would 'pigtail' (proper term?) from the bare ground to the box?

 

If the cable does not have a ground there is no point in adding a grounding pigtail. It would do nothing.

Having larger wire than required on the circuit will not be a problem.

 

The cable does have a ground wire. It's the new line I installed. I would like to make everything safer, instead of running green wire from an outlet to a water pipe 30 feet from the original ground and calling it grounded.

 

Connecting the new ground will not do anything. Still is no path back to the panel in the old wiring. You would have a floating ground.

Water pipes cannot be used to provide a receptacle ground.

 

1. Something such as a transformer or a street utility line needed to be changed. They got almost all of the equipment and wiring in place. Finally they quickly disconnected your home (or more likely) your pole transformer input from the old circuit and then connected it to the new circuit.

2. A tree branch or some other object caused a short circuit between two wires outside. The resulting massive abnormal current succeeded in burning through that object before other breakers upstream tripped, the short circuit current then stopped, and current resumed* its normal flow to the various homes.

* Current to homes did not stop completely. The nature of this kind of short circuit usually results in a substantial voltage drop so your house might be getting, say, 30/60 volts instead of the normal 120/240 volts. The flow in amperes also changes, in this case markedly downwards; the technical reason (utilizing Ohm's Law) is too complicated to describe here. After the short circuit was eliminated, the voltage and amperes went back to normal. If current in any given branch circuit did not exceed that circuit's breaker rating at any time then that breaker would not trip.

 

Right now there are no ground wires (equipment grounding conductors) except in the short length of cable between the "next door neighbor" junction boxes(?)

For now, curl up the required 6" or so bare wire at each end of this short cable inside the respective boxes.

Eventually EGCs (whether in cables or in conduits or coming out of the box to run separately to an appropriate ground) need to be bonded* to each other and to each metal box they enter. Use wire nuts and short lengths (called pigtails when wholly within one box) as needed.

If you run an EGC out of a box and to the nearest water pipe that is not a proper EGC but you may run it down to the main panel (to the neutral bus inside)

Technically you were not allowed to add on to the circuit lacking EGCs so there would have been no good reason to cut the cable and create that next door neighbor box setup. You could lighten the load on a circuit by removing a branch leaving the rest of that circuit unchanged, but a code compliant line (with EGC) would be needed to re-energize the cut branch. Adding a separately run EGC does not make the circuit eligible for additions.

* The box needs just one screw or approved clip holding just one ground wire end, said wire may come from a wire nutted cluster. Note: the screw may not be shared with something else such as a cable clamp.

 

Does it originate at a breaker? If it originates at an ungrounded cable it is not code compliant. Ungrounded circuits can not by code be extended. Also if you made a non compliant extension all receptacles would have to be either ungrounded, two prong receptacles, or GFCI protected three prong receptacles.

You can use a GFCI receptacle to make a ungrounded circuit safer. It does not provide an equipment ground needed for things like surge protectors but it allows the use of three prong plugs and increase personal safety. If you place it as first in a daisy chain of receptacles and connect the downstream receptacles to the load side using grounded receptacles marked No Equipment Ground is code compliant. Stickers for marking the receptacles including the GFCI receptacle should be included with the GFCI.

 

On this circuit, thereis new wire, with ground cable, coming from the panel. I was just uncertain of the grounding of the box. All of the old, ungrounded wire is at the end of the leg, inside the walls, stapled to the studs or else I'd remove it.

 

Since you chose to use a metal box instead of a plastic box you will need to ground each of the boxes.

 

That's an awesome diagram Ray! I actually use the blue plastic boxes, but the metal one was already in place.

So
1. All receptacles should be grounded. Any that are not should be GFCI and be noted 'No Appliance Ground'
2. All metal junction boxes need to be grounded, with a screw solely for that purpose.
3. It is unsafe, and against code, to extend an ungrounded line.
4. To properly, safely, and code-ly add a ground, it must be run from the neutral bus in the panel. Can this line be continued on from one junction/receptacle to another?
5. 6"-8" needed for any splice - don't pull wires tight.
6. Secure wires together before placing the nut.
7. Twist abandoned wires together so they cannot be reenergized accidentally.

Thanks for all the help folks! Any other tips or advice?

 

I would not splice abandoned wires to create an intentional fault.