Not getting 120v from a wall wire

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Old 04-28-16, 07:01 PM
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Not getting 120v from a wall wire

We're doing rennovation on my neighbors house and he hired me to do the electrical. Today I wired a switch to his hall light from the wire coming out of the wall. The light didn't turn on, so I took everything apart and checked the voltage on the wire, it read 33v. Is that not enough for a simple CFL ligh to turn on? Also why isn't it 120? I also touched a piece of metal with one end of the multimeter while the other one to power rail, it also read 33v. What are my options on how to fix this? He definitely needs a light there as that's the only light for a whole flight of stairs and we definitely can't take the walls off to run new wiring.
 
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Old 04-28-16, 07:14 PM
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the voltage on the wire, it read 33v. Is that not enough for a simple CFL ligh to turn on
No. I have to ask what is your background to be helping him with electrical? You don't seem to know even the basics of home electrics.
Also why isn't it 120?
Because you have a bad connection somewhere. If you are using a digital multimeter the voltage may be zero.

Have you read http://www.doityourself.com/forum/el...ther-info.html
 
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Old 04-28-16, 07:20 PM
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I have absolutely no background with household electrical, I have a little knowledge of microchip electrical. But he knows that and he's ok, besides I youtube everything before I do it.

I am using a digital multi, is that a problem? Because the other light switch I did for him was just fine and reading 120.

So how can I fix this problem? Like I said rewiriing is not an option. I was actually thinking of getting a lighbulb that dones't require 120v, I read that you can get them anywhere from 1.2v to 40v. Is that a possible solution? Will it be really dim?

Edit: Another possible thing I thought about is that I can wire him into the neighbors switch. He shares a wall with someone and I have the wall open right now. Can I just cut in right before the switch wire to get the good 120v? He would be on his breaker and power bill but it's just a small light that probably won't be on more than 2 hours a day.
 
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Old 04-28-16, 07:52 PM
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I am using a digital multi, is that a problem?
It is not a problem if you understand what you are reading. Digital multimeter has very high impedance for voltmeter and because of this you can get a phantom reading (induced voltage).

checked the voltage on the wire, it read 33v.
Between what wires did you measure?

I also touched a piece of metal with one end of the multimeter while the other one to power rail
What are you referring to as a piece of metal and power rail?
Are you installing a tracking lighting? Or are you referring to a wire?

How and how wires did you wire?

33V you are reading and most likely a phantom voltage reading on a disconnected wire next to a live wire. This means you have bad connection somewhere.


Residential electrical is very simple and easy if you understand how electricity works. If not, it can be very difficult trouble shooting and can be dangerous.


I can wire him into the neighbors switch. He shares a wall with someone and I have the wall open right now.
That would be illegal and your neighbor can get sued or arrested.

He would be on his breaker and power bill but it's just a small light that probably won't be on more than 2 hours a day
Just tap before electric meter and you can get free electricity. That is until power company finds out. LOL
 
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Old 04-28-16, 08:09 PM
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<What are you referring to as a piece of metal and power rail?
Are you installing a tracking lighting? Or are you referring to a wire?>

Ok, so the first measure between the power and neutral (black and white) was 33v. There is no ground wire, only two wires, so I used a piece of metal to test power to ground, and that was also 33v.

<How and how [many] wires did you wire?>
I'm just wiring a live wire that's coming out of the wall into a regular SPST switch. Connect power cables to top and bottom screws, then piggyback the neutrals to the 3rd screw. It's a very simple job, I wouldn't do anything that I didn't feel confident I could do safely. But on one, I took all the wiring I did off, and just tested the main cable I was using that was running from the wall, and that's the voltage it's giving me, so it's definitely not my wiring.

<That would be illegal and your neighbor can get sued or arrested.>
I think this guy owns the whole house and he's just renting the other half. It might still bee illegal to make your tennants pay your bill, but I'll leave that concern up to him. For me it's important to get it working. Are there any safety reasons why I shouldn't do that? The only thing I can think of is someone who might work on this later and just trust the breakers without checking with multi, might get shocked since the wire won't be on the house breaker.

Also do you know if it's possible to get a low voltage light bulb, I can't understand why a simple cfl requires 120v. Is there some kind of transformer that I could get to maybe run a LED or something?

I just need to hear some options so I can present this to him tomorrow and he'll make the decision, because I have to install the wall and paint it, he's constantly complaining that it's taking too long. (But it has been 6 months already so he might have a point there). In other words I need to finish ASAP.

Edit: So you're saying that there could be no voltage at all on the cable I'm using but I'm still getting a reading of 33v? This "ghosting" is that large? I've seen my multi read 0.1v before on a wire I knew was dead, but only for a few seconds then it goes back to zero. This one variates between 33 and 34 volts.
 

Last edited by Tim Akgayev; 04-28-16 at 08:29 PM.
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Old 04-28-16, 08:33 PM
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No polite way to say this but you reveal you do not know enough to be doing any electrical wiring every time you post. Stop now and tell your friend to call an electrician.
besides I youtube everything before I do it.
They are often good for a laugh but not learning how to do it. You might want to buy Wiring Simplified to get the basics.
 
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Old 04-28-16, 08:34 PM
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There is no ground wire, only two wires, so I used a piece of metal to test power to ground, and that was also 33v.
What type of wire is used in the house? If wire is run in a metallic conduit or AC (BX) cable with bonding wire, the conduit serves as ground and metal junction box is grounded through it.
What is a piece of metal you tested connected to?

If the existing wire does not have ground at all, you are not allowed to extend it.

I'm just wiring a live wire that's coming out of the wall into a regular SPST switch. Connect power cables to top and bottom screws, then piggyback the neutrals to the 3rd screw.
Do you have 120V at this live wire before the switch? If not, you don't have live wire to begin with. You will have to trace this wire back and check the connections.
You will probably have to open up junction boxes and check the voltages.

If you cannot figure it out, it is the time to call a licensed electrician.

then piggyback the neutrals to the 3rd screw.
What 3rd screw? There is only 2 screws on SPST. Are you referring to ground (green) screw?
You should not connect neutral to ground wire.

I can't understand why a simple cfl requires 120v.
Because that is the voltage it is designed to work at. CFL actually runs at much higher voltage and frequency than 120V AC. That is what driver circuit (ballast) does.

Is there some kind of transformer that I could get to maybe run a LED or something?
33V you are getting is probably a induced voltage. A wire running next to a live AC power will have electromagnetically induced voltage. It won't be able to power anything. Current it can provide is probably in uA range.
 

Last edited by lambition; 04-28-16 at 08:56 PM.
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Old 04-28-16, 08:51 PM
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Today I wired a switch to his hall light from the wire coming out of the wall. The light didn't turn on,
I have a feeling that what you think is source power coming out of the wall, the "33 volts", is a switch leg. In other words there is no neutral even though you have a white wire.

If I'm wrong, you still need to understand why I would guess that or you shouldn't be working with electric. My apologies for being frank.
 
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Old 04-28-16, 09:49 PM
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I just rewatched the video I was following, it looks like I mixed up my neutral and ground, I should have been piggybacking the ground the the 3rd green screw, I did that with neutral. Thank you for point that out, I will have to fix the switch I installed today. By the way I ran jammed the ground wire in between the screws in the box, so I hope it's grounded for now.

<What type of wire is used in the house? If wire is run in a metallic conduit or AC (BX)> It is a conduit, the lady at home depot said it was BX I think, I tried to pick one that looks like the rest of the wires in the house.

<What is the piece of metal you tested connected to>
There are a bunch of wire conduits in the wall, so I just touched the shell of the conduit.

<Do you have 120V at this live wire before the switch? If not, you don't have live wire to begin with. You will have to trace this wire back and check the connections.
You will probably have to open up junction boxes and check the voltages.>

I don't have 120v, this wire is reading as 33v. How can I trace the wire back if it's in the wall? I'm not sure what a junction box is though, there is a breaker panel in the kitchen, but it's all the way at the back of the house and this wire is by the front door, so that's a lot of places where it could have gotten damaged. I don't see any way I can actually fix the wire itself.

<Because that is the voltage it is designed to work at. CFL actually runs at much higher voltage and frequency than 120V AC. That is what driver circuit (ballast) does.>
This is just a regular screw in cfl bulb, I guess compact CFL, it's not like a T5 long tube, so there is no ballast, it just screws in the the regular light bulb holder.

<33V you are getting is probably a induced voltage.> So is there any way to actually find out if it's this ghost voltage or actual power? If it was actually 33v would the cfl light up at least a little bit?

By the way I told the guy to call an electrician as I didn't want to mess with it, but he doesn't want to spend any money. The light switches I'm doing for free for him and I'll probably charge like 200 for 5 outlets in the kitchen. He says a pro will cost him a few thousands. Anyways, right now I'm the only person that he has and he's pushing me to finish, so I have to get it done and continue working on the rest of the house.

So right now the consensus is that I can't do anything about this faulty wire right?
 
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Old 04-28-16, 10:09 PM
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I'm just thinking over how I'm going to fix this mistake, I just want to make sure I do it right this time. The wire I bought is BX, it has 4 cables, white, black, red and a thin silver cable. The thin unshielded silver cable is the ground right? And the red wire I don't need at all? Also this silver cable is pretty thin compared to other wires is that normal, like it's so thin that it hard to twist it without snapping it off.

I'm thinking what I'm going to piggyback it with and I just remembered that the wire I'm using for power, that is the wire that came with the house, doesn't have a ground cable, it's got the BX conduit on it, so that's ground? So I have to just tie a piece of wire around the conduit then connect it to a ground wire on my new cable then piggyback an new wire and run it to the 3rd screw?

By the way I didn't stick the conduit portion all the way into the metal box is that a bad thing? I just peeled it back a little and stuck only the wires themselves into the box, the actual conduits are hanging about an inch away, should they be touching the box?

edit: Ok, just read that the bx shield is not a reliable ground and should not be used for that. So what do I ground it to? There is no third cable! And this wire was installed for a long time in this house and was always in use, we're just moving it, so what gives?
 
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Old 04-28-16, 10:35 PM
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Tim.... your getting yourself in a bind here and it's fairly obvious now that you really don't know what you are doing when it comes to electrical work. If your "electrical work" causes a fire.... what will happen then ?

The wire you just purchased is called AC metallic cable. It's like the old style BX. It requires that thin metal bond wire to be wrapped back on the flex before inserting into the connector. When you connect that wire to a box it requires a special connector. You can't just leave the metal jacket close to the box. It MUST be attached.

Now you're saying that none of the metallic jackets are attached to the box ?

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Old 04-28-16, 10:45 PM
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it's not like a T5 long tube, so there is no ballast,
No. The ballast is built into the base.
The thin unshielded silver cable is the ground right?
It is the bonding strip that makes the metallic cable sheath a good ground.
So I have to just tie a piece of wire around the conduit then connect it to a ground wire on my new cable then piggyback an new wire and run it to the 3rd screw?
The conduit itself is the ground. The metal clamp that holds it to the metal box is your grounding means. Devices are grounded by running a green or bare wire from a ground screw in the box to the fixture ground screw. (There are exceptions to what I wrote but that is the basics.)
By the way I didn't stick the conduit portion all the way into the metal box is that a bad thing?
Very bad. Very wrong. Very unsafe. The metallic cable, the bonding strip, the metal cable clamp, and the metal box are your grounding for the circuit. They must be assembled correctly. Metallic cable connector installed in to a metal box. Red hat insulator inserted into cable, bond wire wrapped around end of the cable, cable inserted into the connector.
 

Last edited by ray2047; 04-29-16 at 12:42 AM.
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Old 04-28-16, 11:33 PM
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Thanks for helping me out on this. My question is how do I know that conduit on the old cable is intact and continuous and can carry the current back to ground? It's a pretty old house, I'd say from the 70s, can I really just rely on that cable sheath?

Note that the old cable doesn't have that "bonding strip" at least I don't see it coming out of the end.

I did a bunch of other reading and looked up "using neutral as equipment grounding conductor" and found some article that says it could be done in some cases. That is how I have it now, I wired neutral to the green screw on the switch. So should I just disconnect the neutral from that green screw and just have the metal sheath inserted all the way and it should be enough? What is that screw for anyway then? I looked at it and it's just connected to a metal jacket on the switch, which is screwed on the box, so if the box is grounded the screw doesn't have to be used?

Edit: I'm also thinking of my other switch that I have to install, that has a plastic box, so how do I ground the switch itself if there is no grounding cable and I can't use the sheath of the bx?
 
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Old 04-29-16, 12:23 AM
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"using neutral as equipment grounding conductor" and found some article that says it could be done in some cases.
Yes, if you want to kill someone otherwise NEVER. A bootleg ground can put dangerous electrical charges on the metal case and chassis of every device. They become part of the return path for your neutral.
how do I know that conduit on the old cable is intact and continuous and can carry the current back to ground
There should never be current on the ground. Its only function is to carry fault current long enough to trip the breaker if the hot shorts to the metal case of a device. No ground is needed for devices to function.
I'm also thinking of my other switch that I have to install, that has a plastic box, so how do I ground the switch itself if there is no grounding cable and I can't use the sheath of the bx?
BX cable can not be used with plastic boxes.

Please call an electrician. You do not know enough yet to safely do any electrical work.
 

Last edited by ray2047; 04-29-16 at 12:39 AM.
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Old 04-29-16, 01:17 AM
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...I'll probably charge like 200 for 5 outlets in the kitchen.
If all you charged was five CENTS you would most likely be breaking the law, acting as an electrical contractor. ANYONE that charges another for electrical work needs to comply with all the rules and regulations enforced in the area. I suspect that no permit has been pulled for any of this work either and therefore none of it will be inspected.

PLEASE fill out your forum profile data so we can tell where you live. Almost everywhere has LAWS concerning doing work for hire, especially electrical work. That your friend/neighbor is stingy is no excuse for YOU to be breaking the law.
 
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Old 04-29-16, 02:38 AM
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He appears to be in Brooklyn Furd so you know what that means, no way no how is he allowed to do this work.
 
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Old 04-29-16, 12:15 PM
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Ok, thank you. I will try to fix all of that today. That is remove the "bootleg ground" and get a metal box.
The only thing is that I'm worried that the shield of the old BX cable is not sufficient to ground anything. I think it actually is a real BX cable, in which case I read that it's not advisable to use it's shield as ground.

Any chance anyone can answer my OP question? What do people usually do when a cable goes bad in the wall and the nearest box is across the house? Hm?
 
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Old 04-29-16, 01:02 PM
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I'm worried that the shield of the old BX cable is not sufficient to ground anything.
It probably isn't but in that case you just treat it as an ungrounded circuit. Ungrounded circuits use to be the norm and are generally safe. They are grandfathered and normally can just be left as is. However by code ungrounded circuits can not be extended because there is no ground and any new circuit must meet current code which requires a ground. Any new circuit such as adding lights therefore must be run from the breaker box.
What do people usually do when a cable goes bad in the wall
You run a new cable from the breaker box. Sometimes wall or ceilings must be opened and then repaired if there is no access from an unfinished attic or basement. It is never DIY in an apartment building because it involves access to areas and sometimes opening of walls and ceilings that are not owned by the tenant. Of course if the tenant is not the apartment owner he has no legal right to even do work confined to his apartment.

A renter could be evicted for making repairs, loose his deposit, and be charged for any repairs the owner feels is needed to mitigate damage or liability because of his repairs and to bring the apartment back into code compliance.
 
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Old 04-29-16, 02:17 PM
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@ray247, thanks for the help. I will try to do as you say.
 
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