\When I was working in the computer biz, one of the things we did was
lightning mitigation and analyzing grounding electrodes was a big part
of it. One of the first things you find is there is no such thing as
"ground". I have found up to 35 volts difference between building
ground electrode systems that were less than 50 feet apart and that
was using a low impedance meter. They had what seemed to be very
robust electrodes so the difference was in what earth potential was.
This is generally caused by current imposed on these electrodes. There
are a number of things that can cause this, not the least of which is
a compromised neutral.
Another problem is the voltage drop in the PoCo neutral conductors
I took my clamp on down the street looking at current in the ground
wire on the poles and got some surprising results. There was over 2
amps on some of them.
I had close to an amp on my grounding electrode conductor with my main
breaker turned OFF. (I had a similar number on the PoCo neutral)
I was providing the grounding for the grid.
Granted I have a better ground electrode system than most since it
integrates several thousand square feet of concrete slab, 5 ground
rods, many feet of buried copper wire and an inground concrete pool.
You have several (dryers, ranges and any other 240v appliance with a
120v load), get over it. There may also be some on the 120v circuits
you do not know about. It was common to wire bedrooms on a multiwire
if they were on the other end of the house and split them out in a
ceiling light box. It was just recently that the 2 pole breaker or any
other identification was necessary.
On 05/24/2015 07:57 AM, email@example.com wrote:
There's nothing to "get over".
The shared 120 volt control circuit contained within the metal cabinet of the 240 volt appliance is typically protected (current limited) by a 1 amp fuse or so.
The $10 chinese radio plugged into an Edison circuit wall outlet...not so much.
> There may also be some on the 120v circuits
Not in my home but you are welcome to as many Edison circuits as you like. I fully support your right to do so.
> It was common to wire bedrooms on a multiwire
It's also common and code compliant to use clamps on ground rods too but they always seem to corrode and become loose over time.
I always use an exothermic CADWELD connection. Does the fact I don't use mechanical clamps bother you too?
That is certainly not true in the dryer. The motor is generally 120v
and runs right off the 30a phase leg.
BTW your whole house is on a multiwire circuit from the utility and
they share the neutral and ground on a single, down sized wire.
Doesn't that bother you?
I have never seen a residential cadweld and I have inspected
thousands. I am not bothered by it. You seem to be the one who is
But I suspect there wasn't any wannabe electrician 17 yr old rewiring the
power company's pole-mounted transformers. I know that my house *had* been
rewired by a 17 yr old, so I would (and did) worry way more that any Edison
circuit I found wouldn't be wired correctly in my house, not on the poles
outside. Turns out I was right to worry.
I would guess that any house over 50 years old has had some sort of very
underqualified homeowner "electrician" do some sort of electrical work in
the house. From what people have posted elsewhere, I don't think Edison
circuits are well understood by weekend electricians. Anyone touching
anything they don't understand can lead to trouble. I know that multiwire
circuits are the way the whole power grid works. And I know that Edison
circuits it have some advantages and specific uses. But I think it's clear
that the original reason to use them, cost savings, is extinct, or nearly
That's because 12/3 is way more expensive than 12/2 almost everywhere I
looked (and that's not even using sale prices). 12/3 is SO much more
expensive (nearly twice as much at some sites) that there's no wire cost
savings and very little labor savings. And even if you did manage to save
$20 on wire, the dual pole (or multiple one pole) GFCIs you'll have to buy
to get proper GFCI protection will eat up those meager savings in a NY
there wasn't any wannabe electrician 17 yr old rewiring the
I would not knock the 17 year old. If I was 17 again, I would trust my
wiring more than a licensed electrician I know that is over 50 years old.
Seems like everyone makes a big deal out of wiring a house. As long as the
breakers and wire size is correct and the connections are tight, there is
not much to worry about. Just make sure it is done to code.
That done to code takes me back to the over 50 year old licensed
electrician. I worked with him in a large plant. Most everyone laughed at
himand the way he did things. Never did see why they did not let him go.
Well, I do as the only requirement at the plant was to show up every day.
That man would do outside work for people. Even when the electrical
inspector told him to do something a certain way, he would do it some other
way and complain about how the inspector was always turning his work down.
Well, you didn't see this kid's work, notching joists at exactly the wrong
place, bringing a neutral from a different circuit into his bedroom because
all he had access to was a switch leg and no outlets. He had finished the
basement himself with no insulation or vapor barrier using spike nails that
caused massive damage to the very soft blue cinder block. He also
apparently used scraps of whatever junkheap wire he could find to make his
kluged connections. I had to rip much of it out and start over again. He
also put 20A breakers on old, 15A cloth covered wire because the 15A breaker
that was there "tripped too often."
Are you *still* sure I should trust this guy? (-:
That's not going to encourage your best quality workers to stick around.
The world is full of nitwits, some of them even hold licenses. (-: I am
going to have to relocate a message I saw posted in one of the electrical
forms by someone who makes even you nitwit look competent. He was wrong
about the basics but quoted scientists and legit (though woefully
misapplied) theories to back his claims.
Wiring a home has become a little more complicated with the advent of GFCIs
For me it was a question of what I needed to upgrade protection to the
latest NEC. I found that AFCI double pole breakers for MWC were
non-existent at the time, although now there are a few manufacturers making
Eventually every breaker in a panel will protect against arc faults, ground
faults, overloads and short-circuits because that's where it makes the most
sense to protect branch circuits.
I use GFCI's on the first outlet in circuits that I installed and used the
line connections to protect downstream but that turns out to make trouble
shooting more troublesome. Did the breaker blow? Check the panel. Did the
GFCI trip? Look behind the desk (actually I made damn sure all the GFCIs
were accessible easily, if not visually).
Then I had a devil of a time trying to work AFCIs into the mix and ended up
protecting only two outlets (space heater and A/C) with a discrete
outlet-format AFCI for each because the panel mounted AFCI's were, like 2
pole GFCI, incredibly expensive compared to their outlet-format
wrote: > > +1. To an electrician they are absolutely no problem when properly
He could be right if we're talking split receptacles. They might be
"disallowed" if the circuits were not fed with a tied breaker. The
expectation is that if you kill power to an outlet that both upper and lower
halves will be dead. In the split wire receptacle it requires a tied
But again, why would you want to feed an upper and lower duplex receptacle
from two different circuits when you could just add a second circuit and
outlet? Has anyone ever lived at a place that had *enough* outlets?
On Mon, 25 May 2015 00:44:55 -0400, "Robert Green"
You are arguing with the wrong guy. I am not the one who was promoting
that ancient Canadian split receptacle rule on the countertop.
There is still no good reason why you couldn't bring a MW circuit into
a 2 gang box, put 2 GFCIs in there and split put your counter top
receptacles from there.
That is not what we were originally talking about tho. It was using a
MW to feed the dishwasher and disposal.
To the point of the actual note you responded to, I was asking why
Clare thinks you can't have 2 separate branch circuits in the same
Wouldn't their breakers have to be either dual pole or tied-handle to
address the NEC's obvious concern with leaving something live that someone
might reasonably expect to be dead? I believe lots of people expect that
when they cut power to a breaker (using the plugged-in radio playing loudly
method, for example) that the outlet it controls will be completely dead.
Feeding two discrete circuits from different breakers into one duplex outlet
clearly re-creates that danger in a slightly different format.
Did the same here, running two 20 amp lines seemed silly to me. I did
run them both at the same time right after I installed them to see if it
would trip the breaker while I still had the downstairs wall open. No
problems showed up with both under load.
Here the disposal only runs while we are cleaning off the plates to put
in the dishwasher. The dishwasher isn't turned on until that step is
done so in reality they never run at the same time anyway.
For that kind of "Edison" circuit, the two breakers must be on opposite
sides of the incoming 240V supply. That way each 120V "hot" leg is out of
phase with the other as the AC cycles back and forth. When one leg is
positive, the other leg is negative. The neutral never has more than a
single load on it.
It's a safe and common way to wire some circuits, but I still prefer to run
separate cables for each circuit. That way breakers can be moved around in
the panel if needed without fear of overloading the cable (if both breakers
were placed on the same phase the neutral would carry twice the load). The
cost difference of two cables vs a three-wire cable is usually minimal for
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