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Questions tagged [120-240v]

For question dealing with 120/240V single split phase electrical circuits.

120/240V single (split) phase electrical distribution is a common method of electrical distribution in the United States. A 240V transformer is center tapped to provide 120V hot to "neutral" (center tapped lead), and 240V hot to hot.

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119 questions
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Why Do 240V Circuits Not Require Neutral?

Someone told me that a 240V circuit does not require a neutral wire in the cable. Can anyone explain this phenomenon from the electricity perspective and generally explain why circuits do and do not need a neutral wire?
amphibient
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What is a tandem breaker (aka duplex, cheater, twin, double-stuff, etc.)?

I keep hearing about tandem breakers, and how they won't work with 240V loads and how they should never be used for a multi-wire branch circuit. Aside from those issues... What is a tandem breaker? (note: they can be thrown independently).
Harper - Reinstate Monica
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240 V outlet is not delivering 240 V

I recently moved into an apartment with a 3-prong, NEMA 10-30 outlet. It looks like this: I bought an old dryer that I confirmed was working before purchasing it and hooked it up and unfortunately the dryer never heated up. I suspected something…
Clicquot the Dog
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6 answers

Should I run 240v for any supported appliances?

I am having my main circuit breaker panel replaced (by a licensed electrician) and he told me I can run new circuits for him to hook up to the new panel. Is there any benefit to running 240v circuits for computers, network equipment, other devices…
yakatz
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What are the advantages of running a power tool on 240 V vs 120 V?

I just purchased a band saw and I have the option of running it at 120 V or, by opening the cover on the motor and swapping around a couple of wires, running it at 240 V. In general, I understand that running it on 240 V is "better", but what are…
FreeMan
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Can I use 220 V outlets on a 15 ampere breaker and wire it up as 110 V?

I purchased a 220 V outlet and didn't realize it. My circuit is 15 amperes. I wanted to hook up a series of normal 15 ampere 110 V outlets. When I look at the outlet it looks exactly like a regular 15 ampere 110 V one?...but it has a red, blue, and…
Steve
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Why would replacing this 240 V outlet with a 120 V outlet trip my breaker?

I recently replaced a 20 A 250 V single outlet with a 20 A 125 V single outlet so that I could use it for my microwave in the kitchen. The original outlet had two gold screws and a grounding screw. However, the new outlet has one gold screw, one…
Amy B
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Do travel voltage transformers really not have grounding?

Example 220v-to-110v converter here. It seems like it accepts a 110V plug with grounding, and yet the converter itself only has a two-pronged plug (to a 240v outlet). Does this mean that plugging a device that needs grounding to this converter is…
ispiro
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Will installing European outlet in US change frequency to 50Hz?

I'm planning to buy a Siemens coffee machine from Europe. It uses 220-240V 50Hz. Previous models work just fine in USA using 240V outlet (my electrician was able to get it done, I bought leviton 5031-w). Recent models are different and apparently…
Anis
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Can you use a 2 pole 2-slot wide breaker to provide 240V?

Forgive my ignorance in terminology, I am a computer engineer but not an electrician. The concepts make sense to me, but I don't know all the industry standards and jargon. I recently had a 240V external outlet installed for an EV. Naturally this…
brenzo
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9
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Can I safely plug a 15A 100V appliance into a 20A 250V wall outlet?

I have a convection microwave oven that has a normal 15A 100V plug. I can only conveniently access a 20A 250V outlet, which looks like this: (I am located in Taiwan). Are there any safety issues with finding a way to connect them? What should I…
lifeformed
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Proper way to modernize 1940's cabin sub-panels

This cabin is located in the United States, and was built in the 1940's. However, it has obviously had various electrical panels added to it after its original construction. I'm starting this new question, after my original question opened a can of…
Jimmy
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What is the explicit difference between the ground and neutral wire in 110V systems?

So, I've put in or replaced several outlets following wiring instructions online and in the box. Nothing big. I know that if I fail to turn off the breaker then I shouldn't directly touch the black wire, but touching the white wire or the bare…
Sidney
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Electrical service sizing mix up in Mexico

Facts: The national electrical supply company of Mexico called "Comisión Federal de Electricidad" (CFE) oficially instructs users to install: A two pole one trip main interrupt behind the service drop of "250V/30A" capacity for single phase 120V…
Marian
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Why does my electric oven present the option of 40A and 50A breakers?

The oven in question states 40A with 120/240 volts. In the installation manual: This range is manufactured with the neutral terminal connected to the cabinet. Use a 3-wire, UL Listed. 40- or 50-amp power supply cord (pigtail) (see following…
Andrew Bannerman
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