On Monday, February 19, 2018 at 3:17:15 PM UTC-5, Diesel wrote:
trader_4
Thu, 15
Feb 2018 12:57:54 GMT in alt.home.repair, wrote:
Why would you ever connect the two wires period? YOU are the one
that started talking about connecting the two wires together. The
OP clearly stated what they were talking about. They were
proposing to connect the 240V load between the two circuits that
exist on opposite legs.
The OP mentioned 'combining' them...
The "combining them" is taking the two separate 120V hots that are in the
house now on circuits that are on different legs and bringing them into
a new 240V receptacle. From all that they posted, that's what they proposed
to do. And it will work, except you can't do it code compliant because
not all the conductors for the circuit would be in the same cable.
I agree that last sentence is confusing because they say they want to
combine the two 120V legs to one 240v leg. Reword that to say I will
combine the hots from two 120v legs to one 240V receptacle.
MID:
I bought two mahjong machines in China to use in the US but I forgot
they use 220 over there. So I want to install a US 220V 20A
female receptor by using two legs of 110V 15A circuits and
mounting a box next to one of my 110v outlets. That done I want to
convert that over to 220V, neutral, & ground to run my machines.
The cord into the machine has "L" "N" and "gnd". I want to combine
the two 110 legs to one 220 leg.
*** end paste
They can't combine the two 120volt legs into a single leg as they
wrote they wanted, simply by connecting the two legs to each other.
They never said they were going to simply connect them, they talked
about installing and wiring up a new 240V receptacle powered off of
two hots on separate legs. That's how you get 240V.
I mentioned that for the purposes of clarity, based on what the OP
wrote they would like to do.
If the two 120volts circuits are not fed by the same hot
leg/phase, you WILL most certainly get the arc flash I previously
wrote about if you just try to wire those hots together to create
240volts on a single wire. IE: make a pigtail.
And again, no one except you ever proposed connecting them
together.
Re-read the OPs post...
MID:
I bought two mahjong machines in China to use in the US but I forgot
they use 220 over there. So I want to install a US 220V 20A
female receptor by using two legs of 110V 15A circuits and
mounting a box next to one of my 110v outlets. That done I want to
convert that over to 220V, neutral, & ground to run my machines.
The cord into the machine has "L" "N" and "gnd". I want to combine
the two 110 legs to one 220 leg.
I clearly stated that while it will work, I don't see a way to do
it code compliant.
One, the supply is going to be 240volts across two seperate leg
fed hot wires, instead of one as originally called for.
As originally called for by whom?
The manufacturer who wired it for L,N,G 220volt/50hz
And they can provide it with 240V 60Hz. The 240V goes to the machine
between the L and N terminals.
Three,
neutral is now a hot wire. The direction of current flow does
matter with some things. The internal wiring would tell the tale,
though.
No, the neutral is not a hot wire, it's still a neutral. It
becomes a shared neutral or Edison circuit.
It's not going to be used for the device the OP wants to connect.
Why not?
The device will have two hots and a ground. As the device has line,
neutral, and ground connections intended for connection to an
electrical system that's different than ours. On the intended
electrical system, they get 220volts 50hz/ac on a single hot wire,
where as we get 120volts 60hz/ac on a residential systems hot wire.
We use two hot wires to get 240volts with residential, they don't.
What you fail to grasp is that the machine doesn't care exactly how
the 240V is derived. All it cares is that 240V AC appears between
it's line and neutral terminal. If you do what the poster proposed,
you get 240V.
We seem to have a miscommunication here. I was writing about the
mahjong table device, specifically. I wasn't writing about any
existing circuit taps, edison circuits, etc.
But the whole question posed involved using two existing circuits,
combining them to get 240V to use with the mahjong machine.
Also...
I was doing a tiny amount of researching these tables and came
across this:
https://www.alibaba.com/product-deta...419851227.html
That motor is rated for 220volt/110volt ac.
Rated Voltage:220V/110VAC
Rated Frequency: 50Hz/60Hz
Under product description.
I don't know that his table is using one of those motors
specifically, but, it's possible it is. And, it's also possible
whatever other electrical components are present are also okay with
110volts at 60hz. If it were my table, i'd look into it before I
went and ran another circuit to feed it. It could be nothing more
than attaching a standard american 3 prong power cord to it and
plugging it into a normal 120volt outlet here.
That's possible, depending on what's there.
MID:
I bought two mahjong machines in China to use in the US but I forgot
they use 220 over there. So I want to install a US 220V 20A
female receptor by using two legs of 110V 15A circuits and
mounting a box next to one of my 110v outlets. That done I want to
convert that over to 220V, neutral, & ground to run my machines.
The cord into the machine has "L" "N" and "gnd". I want to combine
the two 110 legs to one 220 leg.
If they are on opposite legs, which is
what the poster said they were going to do, then you have 240V
between them which is what the machine needs.
The machine is wired for 220volts at 50hz on a single hot wire.
And there you go again with the "single wire". That machine uses
two wires, so does a 120V light bulb.
Yes, single hot wire carrying 220volts (or so) at 50hz, where as our
residential ones carry 120 at 60hz...(or so). I didn't say the
machine didn't use two wires. I said it's using one live and one
neutral at 220volts 50hz, in it's current configuration. In order to
convert it to our system and give it 240volts, it won't have a
neutral connection anymore. It'll be our second hot leg, instead.
*shrug*
What is neutral is simply what is the grounded conductor. The eqpt
has a grounded plug, the ground connection will be maintained. There
should be no no electrical difference to the machine at that point as
to whether the wire marked neutral is connected to a grounded conductor
or not.
Like
you'd expect to see in commercial lighting and such here in the
states. 208/277 (at 60hz) etc on a single phase hot wire. As in:
208/277, etc, line to neutral. Not line to line, as you're
suggesting they reconfigure it to be.
Nonsense.
What specifically is nonsense?
It's all irrelevant to the application at hand.
The table has a single L, n, and
ground connection. In order to give it 240volts here from a
residential power source without using a converter is by connecting
our second hot leg to it's neutral. Line to line is what your
suggestion would become.
I'd be surprised if you were unaware of various electrical voltages
available via a single hot wire vs two in the states.
Again back to the one wire. You put 240V into that machine across
two wires. Always two wires. You cannot have a potential difference
and current flow unless there are TWO wires. That one side is called a neutral
in other wiring systems because they have it identified as the
grounded conductor doesn't change the fact that you have 240V AC
across those terminals. Hook up a meter or scope and you see
a 240V AC 60 Hz waveform here, 220V 50 Hz waveform there. Other
than the slight diff in voltage and freq, it looks and acts the
same.
And note that I said you can't use the existing circuits and make it
code compliant, so they instead can run a new 240V circuit. Several
other people recommended that too. Hire an electrician, run a new 240V
circuit. According to you, that can't work either, is that correct?