I discovered a shared neutral in my old house by working in a box that _should_ have been safe. Found the shared circuit is a yardlight on a
3 way switch in the back yard. I still haven't figured out how to correct it without running new wires underground. They only used 12/2 WG for the wiring.Harry K
Pardon me if I don't simply take your word for it. Got any calculations to back that up?
I didn't think so...
How much does it take to kill, Wade?
Hint: the trip threshold on a GFCI is 20 mA.
When are you going to figure out that neutral and ground are NOT the same?
Doug I hope you have all these responses canned in word or something. Seems we just had this thread about a month ago.
The only circuits that will be affected by that are the ones that share a neutral. Loads are not always perfectly balanced so the neutral will most likely always have current going to it.
I figured. End of discussion.
I'm sorry Doug, but my neutrals are tied to ground in the breaker box. Same was true of the last 2 houses I owned.
The service entrance is the *only* place where they *are* the same.
In branch circuits, the ground conductor does *not* carry current in normal operation. It carries current only if there has been a failure somewhere: either the hot or the neutral has faulted to ground somehow.
By contrast, the neutral *is* a current-carrying conductor under normal operation. And that's why you can't presume that it's safe to touch.
In the USA the trip threshold on a class A GFCI is five milliamperes. On a class B GFCI such as the ones built into AFCIs the trip level is thirty milliamperes. Class B GFCIs are only intended to protect equipment.
-- Tom Horne
I regularly install new switches and receptacles with the power on. I touch the black (hot) and white (neutral) wire regularly with the power on, just not at the same time. It is much faster and you don't have to reset any clocks.
If you are slightly cautious, there is absolutely no way you are going to get hurt.
There's a saying that there are old electricians, and there are bold electricians... but there are no old, bold electricians.
That's just foolish.
Make sure your life insurance is paid up.
Hmm. There are hundreds of electricians touching live wires every day. With the proper precautions, it's not only safe, but required.
Think those who maintain the high-voltage distribution network.
Very famous words.
Last words.
Of course -- but you're talking about professionals, who do that on a daily basis. *And* have had proper safety training, besides. This is a homeowner forum. Most of the posters here are *not* pros, and have not had the training and experience that the pros do.
Furthermore, I expect that the guys here who *are* pros would never advise a non-professional that it's safe to work "hot".
I don't do it anymore, cause I really don't like the feeling when I do get shocked. BUT , when I was 13, my parents built on to the house. The electrician was a man my dad worked with. I personally landed some 40-45 duplex outlets and a dozen or more switches all with the power on. Like was said, stand on wood, touch one wire at a time and no problem. AND like I also said, I don't do it anymore.
There was another electrician where my dad worked (a large steel fab plant) who would probe voltages with one hand up to 440v. It all depends on the individual's personal resistance .
There was a hired hand on the farm he grew up on who would shut down the 4 cylinder tractor by putting his arm across all 4 bare spark plug terminals.
According to Doug Miller :
I'll repeat what I said. In those circumstances, the voltage between neutral and ground is at most a volt or two, dependent on IR voltage drop on the neutral due to the load. It doesn't matter how sweaty you are, you're not going to feel it. How sweaty do you have to be to feel 3V off two AA batteries?
The minimum "feel voltage" is at least 10V, and usually considerably higher. If the neutral was connected to ground yet was still showing
10V or more relative to the ground, it'd probably be glowing red hot.Now, if you skewered yourself in the heart muscle with the ground and neutral, you'd feel it. But people tend to avoid that.
The hazard with shared neutrals is contacting a disconnected-from-the-main neutral without having all the hots shut off.
According to Larry Caldwell :
I'd put that a different way. Shared neutrals are incompatible with single pole GFIs. They aren't incompatible with double-pole GFIs, and single GFIs can be used _after_ you split the neutral.
Shared neutral double pole GFIs would be code here for kitchen counters, except that they're so bloody expensive. Shared neutral non-GFI _were_ code, but not anymore.
We've adopted a modified version of the NEC for kitchen counter outlets. You can still use shared neutral, IF you're willing to pay for the dual GFIs, but otherwise, you use 20A singles.
I have 5 split neutral circuits in my shop ;-)
Assuming all the connections in the neutral wire between that point and the service entrance are good.... no imperfectly-formed splices, no high-resistance connections due to corrosion, or improper Al-Cu splices... nothing of that sort...
yes, there are high voltage techs that touch wires, but just once.
The usual useless homemoanershub post where all the others are 15 years old. And the thread is probably stolen from alt.home.repair without attribution.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.