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Can I safely touch a hot 120 wire without touching ground and not get electrocut

Can I safely touch a hot 120 wire without touching ground and not get electrocut

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Old 11-26-12, 06:24 PM
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Can I safely touch a hot 120 wire without touching ground and not get electrocut

Ok, so this is why I'm asking this question. I've never touched a live hot 120v wire. I work in electrical boxes all the time. No real training though other than what I've learned from talking to people.

I've been trying to figure out how to get my wood stove's blower to turn on when the fire is going good and to turn back off when it goes out. My first attempt at it, I bought this sensor off ebay...

wood stove fan/blower thermostat 130F | eBay

The way it works is I need to put the hot 120 volt between the wall outlet to the blower, I need to insert this sensor and attach it to my stove. I got really nervous about doing this. It didn't seem like a smart idea to have a hot 120 volt drapped over a red hot wood stove. All that would need to happen is have the wire's protective sleve melt off and then ground out to the stove and then me touch the stove to open it and get electrocuted...

It does say it works AC and DC. But opening up the blower, there's no DC converter. The straight AC wire goes into the box and directly to the motor.

I first was switching it in the blower. Then I got to thinking, why don't I make a switched outlet. I wired one of those up. It worked. I plugged the blower into the outlet I had the switch on it. If I heated up the sensor with a lighter, the outlet turned on and then I put an ice pack on it and the outlet lost power. I was still very nervous of draping a cord over the stove though. The way I built that one is I used a heavy duty electrical extension cord and I cut it. I used the white wire to go from the incoming AC to the sensor, then the black wire to go back from the sensor to the outlet box to the hot side of the outlet. I put the white from the outlet on the wall to the "extension outlet" and same with ground. Only switched wire was the hot black wire.

(BTW, I didn't switch the outlet in the wall. I put an external switch that was hard wired in an external box that the otherside had a male plug that just plugged into the outlet in the wall.)

The way the sensor was I had to have the hot wire exposed where it connected to the sensor and I couldn't find a way to protect it from being touched with anything that would protect it but not melt when it's connected to a 600+ degree wood stove.

So, to be on the safe side, I bought this gadget...

SS-1 Stovestat | Northline Express

I figured it's factory made. It has to be safe. At least safer than I know how to make as an amature. It looks safe in the picture until you see the other side of the bracket...

I'm attaching a picture I took...Name:  photo.jpg
Views: 3895
Size:  24.9 KB

You can see in that picture out of the black box where it connects to the silver bracket, there's a head of a screw. I assumed that had to be a hot 120 v wire seeing I already bought the sensor without the professional setup. So, I took my DMM and then first checked voltage on the outlet. I stuck the red in what I assumed was hot and black in what I assumed neutral was. I got a +120v which told me I had my polarity right.

I then left the black in that outlet (while this gizmo was still plugged into another outet right above the outlet I'm using as a ground), then stuck the red lead on the screw that's visible on the top and I got a +120v.

I have little kids. Last thing I need them to do is walk over to my wood stove and touch this little box and get electrocuted.

But what would happen if someone touched it? It's a +120v but the person isn't grounded, are they? They're standing on a brick or wood floor in that spot. I guess if they're touching the wood stove's surface, it's cast iron, but it has a blower on the back that's connected to the whole body and the blower is plugged in and grounded... So, I don't know.
 
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Old 11-26-12, 06:34 PM
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Honestly confused by your post but there should be no exposed wires. The Stovestat plugs into the receptacle and your blower plugs in to the female receptacle built into the top of the plug. If the blower is hard wired then you need to connect a cord set to it instead of the hard wire connection.

Is the picture of the Stovestat? I can't see well enough to understand.
 
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Old 11-26-12, 06:36 PM
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You can see in my picture below, the only exposed wire is the wire they did out of the factory. The silver bracket coming out of the black box, there is a wire. That is there by the factory. If you check it with a DMM, it's 120v unprotected at that point. I did not modify it at all.
 
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Old 11-26-12, 06:43 PM
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I am also confused......and when I'm confused things sound dangerous.

What is that device ? Some kind of heat sensor ?

There should NEVER be anything exposed that has 120 volts on it......ever !!
 
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Old 11-26-12, 06:44 PM
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Name:  photo2.jpg
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Size:  40.4 KBHere is a zoomed out picture of the setup. There are no exposed wires except where the bracket meets the wood stove...
 
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Old 11-26-12, 06:48 PM
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Here's a pic really zoomed in. That silver wire coming out of the black box going to the circle is a hot 120v wire.Name:  photo3.jpg
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Old 11-26-12, 06:48 PM
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What voltage measuring between the screws on the sensor?
 
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Old 11-26-12, 06:49 PM
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It just hit me what you are doing......you are checking from 120v to that thermostat device which looks to be grounded. Of course you're going to see voltage. Check from ground....like the ground screw on the electrical box to that screw. You should see 0 v.
 
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Old 11-26-12, 06:51 PM
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the voltage reading going between the two screws on the bracket are like .01... tiny. But I'd expect that. Going between the bracket and ground is 120v.
 
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Old 11-26-12, 06:54 PM
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no, my test that i showed 120 v, I stuck the black lead in the neutral of the 120v outlet just below where my gizmo is plugged in the wall. The red lead, I touched the top of the stove stat where the screw is on the bracket completely open to the world.
 
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Old 11-26-12, 06:55 PM
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How did you determine this wire was hot? What measuring method are you using. Are you using a multimeter? If so what are you grounding to? Is this thing magnetic? Are there two cords coming off this unit? One to the fan and one to the receptacle?

Cardinal rule.......no shock. Don't try it, even for a rush. It ain't fun.

You were typing and I am slow and old. Test from that wire to a known ground, not neutral. Use the grounding lug on the extension cord if necessary.
 
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Old 11-26-12, 07:00 PM
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ok, i feel like everyone keeps asking me the same questions and I seem to give the same answers. If I'm explaining wrong, please let me know.

chandler


How did you determine this wire was hot? What measuring method are you using. Are you using a multimeter? If so what are you grounding to? Is this thing magnetic? Are there two cords coming off this unit? One to the fan and one to the receptacle?

Cardinal rule.......no shock. Don't try it, even for a rush. It ain't fun.


Read more: http://www.doityourself.com/forum/ne...#ixzz2DO7d4wUw
I used my digital mutimeter. I put the negative of the dmm to a neutral wire in an open outlet just one receptical down (same spot on the wall just the other of the two recepitcals.) The red wire I touched to the top of the screw that hooks to the bracket on the stove stat. It registered 120V AC.

It is magnetic. That's how it holds to the stove.

The fan of the stove plugs into the stove stat and the stove stat plugs into the wall. I attached a picture earlier zoomed out so you can see the overall setup.
 
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Old 11-26-12, 07:00 PM
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I'm not quite sure what the issue is here but if you're telling us that between a KNOWN ground and any part of that Stovestat you measure 120 V ..... that piece is defective. Send it back to the company or call them. I looked over the specs and design......it doesn't appear that there would be live voltage on it but it may be defective.

Also while we're on this subject.....Stovestat.....here is some data I got from their site :
  • Rated 4.4 amps at 115 volt, 2.2 amps at 230 volt
  • To be used only on double wall stoves. Cannot be used on single wall stoves.
  • Blower will start automatically when the stove heat exchanger reaches approx. 110 The blower will turn off when it reaches approx. 90 F
  • Are you using it on a single or double wall stove.
 
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Old 11-26-12, 07:03 PM
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We may be asking duplicate questions, but you should not have any exposed line voltage. Are you absolutely sure you had your probe in the neutral of the receptacle. It is the large slot. Please verify that, or retest using the grounding part of the receptacle. We don't want you or your kids hurt.
 
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Old 11-26-12, 07:08 PM
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I'm not quite sure what the issue is here but if you're telling us that between a KNOWN ground and any part of that Stovestat you measure 120 V ..... that piece is defective. Send it back to the company or call them. I looked over the specs and design......it doesn't appear that there would be live voltage on it but it may be defective.

Also while we're on this subject.....Stovestat.....here is some data I got from their site :





Rated 4.4 amps at 115 volt, 2.2 amps at 230 volt
To be used only on double wall stoves. Cannot be used on single wall stoves.
Blower will start automatically when the stove heat exchanger reaches approx. 110 The blower will turn off when it reaches approx. 90 F
Are you using it on a single or double wall stove.


Read more: http://www.doityourself.com/forum/el...#ixzz2DO9e3ZOJ
I know the device isn't defective. Seeing I attempted to wire one up, I know how they work inside and the way they did it was pretty much the way I did it because it has to be that way. What kind of protection can they put over it that can withstand 600+ degrees? I looked at all the pictures. No other ones have protection there. The sensor in that box is switching a hot 120v wire. So, it has to have the 120 v wire going to it. So, I don't know how they can get around the physics of it.

So, I cant imagine I have a defective one, but I can't imagine people touch these things and get killed constantly. I don't feel like being the guiney pig to see if I do get electrocuted (or worse one of my toddlers running around here.)
 
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Old 11-26-12, 07:14 PM
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We may be asking duplicate questions, but you should not have any exposed line voltage. Are you absolutely sure you had your probe in the neutral of the receptacle. It is the large slot. Please verify that, or retest using the grounding part of the receptacle. We don't want you or your kids hurt.

Read more: http://www.doityourself.com/forum/el...#ixzz2DOBThyBB
I know I tested it right at the outlet. If I would've tested it wrong and say had the negative prong of the dmm in the positive hot outlet and touched the red dmm prong to a hot lead on the sensor, i would've registered 0 volts.

If I were to accidently have the black lead in the hot wire of the outlet and the red lead on the sensor but it was ground, I would've registered a -120v. Because it showed +120v, I'm sure I measured it right.

The reason I'm looking at this close is because I did wire one up. Before doing it, I asked these questions. I posted the suggestion of why don't I switch the negative wire? In DC car electronics, I typically switch the DC because if it shorts out, no one is going to get hurt. But the response I got was I always have to switch AC on the hot wire. I can't switch the neutral wire. So, that's why I see a hot voltage at the top of the sensor.
 
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Old 11-26-12, 07:18 PM
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Of all the internet pictures of these, I have not seen one with an exposed wire. The electronics are in an enclosed housing, with the heat probe sticking out and a magnet to hold it to the metal stove. If you are reading -120 volts, you have your dmm in DC mode.
 
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Old 11-26-12, 07:22 PM
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I know the unit works BUT if you can measure hazardous voltage on it then it's defective.

You should have your meter on AC not DC. You should be measuring from a KNOWN ground like the plate screw. Don't stick any probes into the outlet.

That unit is NOT designed to be use on something that is that hot. That is why they highlight double wall stove.
 
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Old 11-26-12, 07:28 PM
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Ok, so maybe I'm wrong. I just did a little more testing. I think I tested it wrong. When putting the black lead of the DMM in the large slot in the wall and the red lead of the DMM to the base, I show 0 volts. When I take the red lead of the DMM and put it in the small slot in the wall and the black lead on the sensor, then I show 120 v. So, I think that's showing me the plate there is just acting as a ground.

I have one of those devices I can stick next to a circuit and it beeps if it's live. Maybe I'll try that tomorrow next to it. Although it probably will register no matter what. Might just have to do the touch test.... I don't know about that though.
 
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Old 11-26-12, 07:31 PM
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I have my DMM in AC mode. I'm sure of that. (The sine wave.) It's the other side of the bracket you're not seeing in this picture above. See that circle inside the magnet, other side of that there's a wire exposed running into the black box. That's what I'm worried about and the idea that exposed wire touches that metal bracket.
 
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Old 11-26-12, 07:32 PM
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It's not only acting like a ground....it is ground. That's why that t'stat has a 3 pin power cord on it.

That exposed wire is the ground wire because you can't ground to a plastic box.
 
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Old 11-26-12, 07:35 PM
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Alrighty, then, we'll stand down. We all, I feel, were concerned with you either having a defective unit, or mis measuring, which I am glad it was the latter. With a non contact device, it will beep, because the thing is energized within, so don't be alarmed. You have done the proper testing and there is no live line voltage there, and that's good.
I will not advocate the use of the human body to detect presence of current. We all know that if you touch a live wire with your fingers, your hand will clamp down on it and you may not be able to let go with high enough voltage......toast. Touching it with the back of the finger will cause your hand to jump off the wire by natural reaction and will not clamp on the wire. Now, that is a story from way back and may or may not have merit, so be prudent and do the "no shock" thing.

Bedtime, guys.....0500 comes early.
 
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