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Rob2k
@217.148.114.x

Rob2k

Anon

[Electrical] NEMA standards

Dear all, I would like to know whether US houses have a 240V split-phase line, please. I am from Italy and I need to connect to a US 240V line without any kind of transformer. Moreover: is NEMA 14-20 an actual standard? Otherwise what would you please suggest to connect to a 240V split-phase line? There would be a 1A-current flowing only.
Thanks in advance!

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
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tschmidt

MVM

Correct: the US, unlike most of the rest of the world, uses a 120/240 volt system rather then 240v. Also the US system is 60Hz rather then 50Hz used by the rest of the world. Except for things like TVs the difference in frequency should not be an issue, but check the nameplate.

Since you are trying to connect a low current 240v device you could use a NEMA 14-20, but they are not in common use and it is overkill for your application. A NEMA 6 is more suitable. That is a 240V receptacle. To use it need to install a 240V branch circuit protected by a two-pole circuit breaker.

»en.wikipedia.org/wiki/NE ··· onnector

/tom

Rob2k
@217.148.114.x

Rob2k

Anon

Thanks, dear tschmidt!
One more question, please: as I have to connect the Neutral line too (while Ground is not necessary), on the link You posted I saw that all NEMA 6 don't meet my needs. What would You suggest then, please?

cybersaga
join:2011-12-19
Selby, ON

cybersaga

Member

The only reason to connect to a neutral is if the appliance uses 120V as well as 240V (such as the electronic controls for a stove or a clothes dryer). In North America, you get 240V by using two hot wires, without a neutral.

But if that is the case here and you do need a neutral, then take a look at the diagram on that Wikipedia article: »en.wikipedia.org/wiki/NE ··· pins.svg

The ones that start with "L" are locking, meaning you have to push the plug in and turn to lock it in place. You probably don't need that.

The 10-30 and 10-50 do not have grounds, but those are 30A and 50A outlets, which would mean that the wire running to them has to be rated for 30A or 50A, which will cost you more when you don't need that much current.

The 14-20 has both a ground and neutral, and would be cheaper to wire.

tschmidt
MVM
join:2000-11-12
Milford, NH

tschmidt to Rob2k

MVM

to Rob2k
Why don't you think a NEMA 6 is appropriate?

A US 240V device uses both "hots" for power and ground for safety, neutral is not needed. In the US Neutral is only needed for 120V.

/tom

Rob2k
@217.148.114.x

Rob2k

Anon

Thanks to all of you.

printscreen
join:2003-11-01
Juana Diaz, PR

printscreen to tschmidt

Member

to tschmidt
said by tschmidt:

Except for things like TVs the difference in frequency should not be an issue

That is not true for devices with AC motors in them. The motors will run faster on 60 Hz. Whether this is an issue or not depends on the device itself.

For a TV the issue is not with the frequency (provided you can actually use it on US power) but with the broadcast signals and video signals which are a different standard

leibold
MVM
join:2002-07-09
Sunnyvale, CA
Netgear CG3000DCR
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leibold

MVM

I think Tom is dating himself with his comment on TVs and line frequency. There were in fact very early TVs that used line frequency either directly or as a synchronization source for the vertical oscillator. I don't think this is the case for any TV made in this millennium

Besides the speed of AC motors, the most noticeable effect of a 50/60Hz line frequency switch are clocks that use it. Typically those are alarm clocks (clock radios) and clocks built into appliances (e.g. microwave, coffee maker).

SparkChaser
Premium Member
join:2000-06-06
Downingtown, PA

1 recommendation

SparkChaser

Premium Member

Tom did say "check the nameplate."

Can't cover it more than that.

printscreen
join:2003-11-01
Juana Diaz, PR

printscreen to leibold

Member

to leibold
said by leibold:

I think Tom is dating himself with his comment on TVs and line frequency. There were in fact very early TVs that used line frequency either directly or as a synchronization source for the vertical oscillator. I don't think this is the case for any TV made in this millennium

Just out of curiosity I looked at the manual for my 2007 HDTV interestingly enough, it is able to operate in Europe with just the proper cable of with a plug adapter. The manual says 100-240 VAC and 50/60Hz. But I don't think it can work with OTA signals across the pond and likely won't take PAL composite, S-Video or component video signals.

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
·Hollis Hosting

tschmidt to leibold

MVM

to leibold
said by leibold:

I think Tom is dating himself with his comment on TVs and line frequency.

Yea, I was thinking Vert sync on analog TVs.

But as others have posted anything with a synchronous motor will be affected by the difference in line frequency. Analog clocks are the first thing that comes to mind.

As printscreen See Profile pointed out the TV issue is not mains power but because rest of world uses a different standard.

/tom

leibold
MVM
join:2002-07-09
Sunnyvale, CA
Netgear CG3000DCR
ZyXEL P-663HN-51

1 recommendation

leibold to printscreen

MVM

to printscreen
Once upon a time the difference in TV standards was NTSC (North America) versus PAL & SECAM (Europe and many other countries). These days the difference is ATSC (North America) versus DVB (rest of the world). The former are analog standards and the latter are digital (where DVB is an entire suite of standards for terrestrial "over-the-air" TV (DVB-T), cable TV (DVB-C) and satellite TV (DVB-S)).

Composite and S-Video have color information encoded based on one of the analog standards (NTSC, PAL or SECAM).
However in Component video the color is not encoded and it is therefore likely to work universally (there is still the issue with different screen formats and the timing of horizontal and vertical synchronization).