Thread: 110v between hot line and concrete floor

1. 110v between hot line and concrete floor

I was working on a oil furnace today and was testing the primary control, I has one probe of my meter on th line voltage and the other probe was touching the floor and meter started beeping. I look and it says 115 or whatever so I keep trying and every time the same thing. I guess it's possible but just thought it was wierd.

2. Hot to ground = 120v. Say your standing on concrete with rubber soled shoes. You can grab that hot wire and it wont shock you. Take your shoe off and grab that hot wire. zingg

3. Originally Posted by ar_hvac_man
Hot to ground = 120v. Say your standing on concrete with rubber soled shoes. You can grab that hot wire and it wont shock you. Take your shoe off and grab that hot wire. zingg
Ya I get it just surprised me, didn't think I would get 120 to the floor.

4. lol i learned the hard way, working on my washing machine in nothing but boxers

5. Originally Posted by ar_hvac_man
lol i learned the hard way, working on my washing machine in nothing but boxers
I guess that's when you know it's time to fix the washer, when all you have left is underwear lol.

6. I guess that's when you know it's time to fix the washer, when all you have left is underwear lol.

LMFAO...so true so true.....

7. Today, system grounds are bonded to piping, structural steel, and rebar embedded in concrete. You are reading 120v because those bonds are connected to the system neutral at the panel. In this case, your concrete is completing a high impedance circuit to your ground rod, and to the neutral at the panel.

8. Professional Member*
Join Date
Aug 2007
Location
Northern VA 38 degrees N by 76 degrees W
Posts
5,093
Post Likes
Originally Posted by timebuilder
Today, system grounds are bonded to piping, structural steel, and rebar embedded in concrete. You are reading 120v because those bonds are connected to the system neutral at the panel. In this case, your concrete is completing a high impedance circuit to your ground rod, and to the neutral at the panel.
That should be low impedance.

9. Originally Posted by second opinion
That should be low impedance.
It "should be," but in his case, it is not. HE has a high impedance path between his concrete and the neutral bar in his service panel, probably via the ground under the concrete and out to his grounding electrode, and back to the neutral bar.

10. Thanks timebuilder it makes sense now, at the time I didnt think of it like that, I feel dumb now for even mentioning it as I do some electrical work with our sparky sinking ground rods and such.

11. Originally Posted by timebuilder
It "should be," but in his case, it is not. HE has a high impedance path between his concrete and the neutral bar in his service panel, probably via the ground under the concrete and out to his grounding electrode, and back to the neutral bar.
I'm wondering if the fact that the floor was wet (100 year old house leaky basement) it helped the process?

12. concrete also loves humidity and acts like a sponge

13. Regular Guest
Join Date
Nov 2008
Posts
1,673
Post Likes
Concrete is a semiconductor and wet concrete is a pretty good conductor. See if you can light a 7-1/2W bulb that's hooked up between the hot line and the floor. If that works, try a 100W bulb.

Since you're not dead I guess the current flow, 120v through concrete resistance through skin resistance through body resistance and back through skin resistance was less than 20 mA or so. 10 mA is painful and 1 mA is a tingle.

Page 1 of 2 12 Last

Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

Related Forums

The place where Electrical professionals meet.