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@REPLYADDR Bob La Londe <none@none.com99>
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On 9/28/2023 4:10 PM, Jim Wilkins wrote:
> "Bob La Londe" wrote in message news:uf4bic$3p2la$
3@dont-email.me...
>
> In the US residential and non-industrial is usually split phase. We
> have a single phase coming in, but its got a half tap at the service
> transformer for 120V nominal which is what most small to medium devices
> are designed to work with. The 120V device can be wire from either leg
> to the half tap or neutral. It makes for some interesting conversations
> with other do-it-yourselfers. In the past there were house which only
> received half phase. That is their service entrance was 120V nominal
> only.
>
> I may not have the terms exactly right, but that`s the gist of it. Like
> I said, it makes wiring in extra stuff interesting.
>
> -------------------------
> I remember the single drop and 60A screw-in fusebox. My father bought
> and remodeled old houses as a sideline, I think because it gave him
> problems he could solve with a hammer. He became pretty good at
> everything except 3-way light switches. I might have helped him more if
> my role hadn`t been the nail.
The internet solved three way switches for me. The first time I saw a
circuit diagram I understood it.
>
> I would describe the US residential service as coming from a
> center-tapped transformer secondary winding with the center tap defined
> as neutral and grounded, thus the two ends of the secondary are 120V at
> 180 degrees apart, each is 120V to neutral and 240V to the other one. In
> the breaker box the connecting tabs to the two hot "phases"
I never said two phases, because its not. I said split phase. You are
literally half tapping one transformer. No different than multiple tap
transformers for power supplies or commercial sound systems.
are
> interleaved such that a double breaker connects to both for 240V, a
> single breaker to one for 120V, and the single breakers above and below
> it are the opposite phase so hopefully the electrician will more or less
> balance the loads between them as he works his way down. >
> Large loads such as the kitchen stove, water heater and clothes dryer
> use double breakers for 240V, wall outlets and room overhead lighting
> uses single ones for 120V, with the loads connected in series unlike the
> British loop that feeds from both ends. The wall outlets and switched
> ceiling lighting in each room are supposed to be on different breakers
> so the room can be lit with one while the other is shut off for
> maintenance. Back when I learned this the wall outlet circuits were
> wired for 20A and the lighting for 15A, with thinner wire. Sometimes a
> wall switch controls an outlet meant for a lamp, especially if there
> isn`t an overhead ceiling lamp which could cause a leak in the insulation.
Are you saying all of that because you think I don`t know it, or to help
somebody else who might be reading it? I was taught basic res/com
electrical at a young age by my dad. Before I learned refrigeration
(also at a young age). Its kind of a requirement to know basic
electrical before working on refrigeration equipment.
>
> There can be variations. My house has a separate meter and breaker box
> for the water heater which is billed at a lower rate. The main drop is
> 200A for the baseboard electric heating that was expected to be cheap
> nuclear in 1970. Rooftop solar uses a different meter that records power
> bought and sold by the customer separately. Determining the direction of
> AC is actually easy, a phone does it with voice to send and receive on a
> single pair of wires.
Now that`s interesting. I have heard of farm shops with a residence and
a shop on different services, but some farm shops also have three phase
power. I`ve even seen well pumps on their own service, but two
different service on a single residence is a new one on me. When I
installed the sub panel on my shop I did install a meter, but its not a
separate service. I just installed the meter so I could track power
usage for tax purposes.
>
> Another difference from British practice is the fuse isn`t in the plug,
> unless it`s a built-in ground fault interrupter. It protects the house
> wiring, the appliance is its designers problem. Old fuse boxes were
> meant to have the center contact of the screw-in fuse hot so that once
> you unscrewed the fuse part way the more accessible threaded shell was
> safe to accidentally touch, which it wouldn`t be with a ring main.
> Holders for cylindrical glass automotive fuses that can be used for 120V
> should be wired the same way, hot at the inner end.
>
> You can identify which breaker controls an outlet without a helper by
> plugging in a vacuum cleaner that vibrates the floor and can be heard
> from far away.
Ha Ha Ha... okay. Or I could use my circuit tracer. If its a panel
I`ve worked in before most of the breakers are marked with a paint
marker anyway.
>
> Although house wiring is sometimes considered two phase,
I never said two phase, and I`ve never heard anybody call it that. Well
nobody I consider knowledgeable. I said split phase. I do not know
that is technically a correct term, but its fairly descriptive, and I
have heard that term used before.
that term is
> formally reserved for separate circuits 90 degrees apart which was
> Tesla`s original sine and cosine supply that created a smoothly rotating
> magnetic field to eliminate DC motor brushes. It required four
> distribution wires while 3 phases at 120 degrees apart could be done
> more cheaply with three and so replaced it.
>
> Industrial schematics label the phases and the wires themselves L1, L2
> and L3 (L=Line) ,and each succeeding wire connection takes an increasing
> numerical prefix, so that the wires coming from the 3 phase breaker may
> be 1L1, 1L2, 1L3, then 2L1, 2L2, 2L3 from a contactor to a motor, etc.
> The parallel lines that look like a capacitor are normally open relay
> contacts that should have their associated Control Relay (CR) indicated
> with a circle for the coil. The N-like variant is a normally closed
> contact, normally meaning powered off. This is called a ladder diagram
> because the power lines are usually vertical and the relay contacts and
> coils etc drawn horizontally between them.
>
> -jsw
--
Bob La Londe
CNC Molds N Stuff
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