Hot answers tagged

48

In a 120/240V single split phase system, the two ungrounded (hot) legs are actually connected to the secondary winding of the distribution transformer. The transformer actually steps down the voltage to 240 volts, so the two legs are a complete 240 volt circuit. The grounded (neutral) conductor is connected to the center of the coil (center tap), which is ...


44

Edit: This is sounding more and more like a problem with either a neighbor's electrical or the utility's supply. See last entry. DON'T get in that hot tub again! The "very small" shock was due to high impedance between you and the current. Impedance is extremely luck-based. Someone getting out of the pool might splash water where it had not been before, ...


33

Wrong socket! Wrong socket! Wrong socket! That obsolete, dangerous NEMA 10 socket is bad news anywhere you see it. You wired this? Never use a NEMA 10 socket ever again. It should not have been sold to you, and make them take it back. It is illegal except for exact replacement of a broken one. Do these look like your numbers? That is wild-leg delta. ...


26

I bet if you go to your service panel, you're going to find a completely full service panel, and a unique creature we call a "double-stuff breaker". Quite likely the landlord does his own electrical work or pays a dumb handyman (naughty naughty). He's out of space in the panel, so he resorted to those double-stuffs. He moved the dryer from a 2-pole ...


23

For an old installation, there are some "shortcuts" grandfathered in, but even those are based on "no ground but have a neutral". You have the opposite - and much worse - problem of "no neutral but have a ground". Rip out the 8/2 and put 8/3 in place. That will give you two hots (typically black & red), neutral (white) and ground (bare or green). ...


22

Yeah, the root problem is, you see they are both tied together in the panel, but you don't know what that thing is... or you don't even realize that is a thing. Its name is the Neutral-Ground Equipotential Bond. Since we don't know what it is, let's get rid of it. SNIP! Life without an Equipotential Bond Now, your 2 hots are 240V apart, and neutral ...


20

Here's what 3-phase delta looks like. This happens to be 240V and uses the common 3-phase colors of black, red, blue. It's that simple, folks. 3 phases, No Neutral. One error of belief is thinking every service must have a neutral. It doesn't. This was Tesla's genius. Delta is used in industrial facilities where a few tools need a medium amount ...


20

Two issues: In the world of electrical power devices, there is a "Distribution Voltage" that your utility is providing to you, and there is a "Utilization Voltage" that your devices are designed to work on. They are not the same values, because it is EXPECTED that there will be a "voltage drop" that takes place between the utility transformer and the point ...


18

Power doesn't want to return to earth. It wants to return to source. For natural power, ESD and lightning, yeah, source is earth. However, for human power, source is the transformer or battery. So hot wants to get back to neutral or the other hot. As it happens, there's an equipotential bond to keep the three voltages (240V and neutral in the middle)...


15

It can be done, but you'll have to swap out the breaker. A "standard" US receptacle is rated for 125 volts, and 15 or 20 amperes. So you'll be going from a 30 ampere double pole breaker, to a 15 or 20 ampere single pole breaker. You could install a 15 or 20 ampere double pole breaker, but since you're not using the second line there's no point. In ...


14

Yes, you can certainly do this. It is referred to as a Multi-Wire Branch Circuit. The two hot legs share the neutral. It is quite common. Note: Make sure you pigtail the neutral and ground wires, do NOT daisy chain them through the receptacles. Here is a pertinent National Electrical Code reference: 210.4 Multiwire Branch Circuits. (A) General. ...


14

I had an electrician to check out the problem and: I am in the UK and there is only live and neutral at the meter (earth and neutral are the same wire at that point) The Hot Tub water is directly conncted to Earth The mains electrics in my property all checked out fine, incoming supply fine. No faults with the Hob Tub RCD's tested and working He is ...


13

tl;dr 15 Ampere cord-and-plug appliances can indeed, safely be connected to 20 Ampere receptacles. A deeper understanding NEMA 6 is a design standard for three wire grounded cord-and-plug devices and receptacles. The number after the dash (-), is the current rating of the device. For example. A NEMA 6-20 device, would be a three wire grounded cord-and-plug ...


13

220/230/240 are the same thing, really US single phase line-to-line mains voltage is interchangeably referred to as 220V, 230V, and 240V. This is because it started off as 220V, but was raised incrementally over time to deal with increasing demands on the grid; right now, it's said to be 240V at the service entrance, but 230V at loads to account for ...


13

In my humble opinion, I'd run #6-3 w/ground from the panel to a outlet box accessible from the outside and just cover it with a water tight cover. Wait until you get your car and then get the breaker and outlet according to the specs for your car. If you're running conduit, run a 1" conduit from panel to outlet box and pull the wire later on when you know ...


12

This is a fairly "common" issue, that typically occurs due to high resistance at the terminal. The high resistance can be caused by corrosion, or a loose connection. The high resistance causes heating, which causes higher resistance, which leads to more heating. Eventually the insulation on the wire starts to melt, and/or burn. Usually the heat ...


12

Input Phase Angle and number of transformers needed. For High-Delta, type of transformer. All voltages below are expressed in RMS Average, not Peak... I find it really hard to refer to Split-Phase as Residential or "House" Power. It is used in business where you're not running a lot of heavy motorized equipment. 240VAC Split Phase is produced off a single ...


12

First you need to figure out the parts you need. Turn the power to the circuit off and remove the outlet. You need to figure out the gauge of the existing wiring. Since it is a 30 amp circuit, the wire should be 10 gauge, so my answer will mostly assume that. Now you can go to the store and buy a 20 amp outlet, a face plate, a 20 amp breaker, and a breaker ...


12

One possibility is that the two hots, labelled X and Y, are on the same line or leg of the service. The 240V electrical service typical in the US is a three wire Edison circuit, with two of the service wires, commonly called the legs or lines, designated L1 and L2, are at 240VAC at 60Hz, with the neutral tapped midway between the two - 120V L1 to N and ...


11

You can't do that. It'll fry your equipment. What you have is 240V "wild leg delta" (orange phase). This is 240V delta with a neutral point inserted halfway between red and black phases. It is 240V specifically, so it will be 120V from neutral to red and black hots, and 208V from neutral to orange hot. This gives it compatibility with 120/240V split ...


10

You are correct. The issues at hand are common maintenance shutoff (to solve the problem of which you speak) and common trip (to entirely remove power from a device with a problem). If the circuit serves a device that uses only 240V and does not supply neutral, then common maintenance shutoff will suffice. Go to an electrical supply house that deals in ...


9

A subpanel is probably the safest bet. It will allow easier access to cut power in an emergency, and it will offer better protection of the wiring. If you go with option 1, you'll have to step down to #12 or #14 wire at some point to feed 120V receptacles. Which means you'll potentially be able to draw 30 amps on a #12/#14 wire, before the breaker trips. ...


9

Yes, you are correct. You can wire the heater across any two of the three phases.


9

What everyone has said is fine, but here is an optional method I would use. First straighten the wire out as best you can. I usually us a pair of lineman's pliers our a heavy duty needle nose. Then you can purchase some shrink insulation from your local hardware store or electrical supplier and shrink a new piece of insulation around the nicked area. I ...


9

You can't do that. That's been outlawed since 1989. You need to redo the circuit using 8/3 cable (or 6/3 if you aim to breaker it for 50A). You need to wire a separate neutral/ground and bring it into a NEMA 14-50 receptacle (if you use receptacles, that's not required). You also need to jumper the oven for a 4-wire connection, which means removing a ...


9

That white wire can just...go Since your new range doesn't use a neutral, and this circuit appears to be run in conduit, I would turn off the feeder to the subpanel box at the main panel, make sure the power's off in the sub, then unhook the white wire headed rangeward from the neutral bar of the subpanel and pull it out as a starting point. While this may ...


8

There should be no problem with opening the box, removing the outlet fixture and then putting wire nuts on the ends of the wires. It may be necessary to straighten the wire ends and trimming slightly if the bare wire ends are too long to be nicely covered by the wire nut. Some folks go the extra step of wrapping the wire nut and the end of the wire with ...


8

Be sure you use a 30A double-pole breaker to adequately protect your wiring. Make sure you provide an equipment ground and use a NEMA 14-30 receptacle. The box can be metal or plastic. Some form of cable clamp is always required, it's just that most plastic boxes have an integrated clamp (that finger-trap style door). If using NM cable, The cable must be ...


8

In NYC, you will have 208V power. It's 3-phase, but that won't be an issue. Grounding path Through discussion, we've determined fairly conclusively that a) this complex's wiring is grounded, and b) the grounding is via conduit or AC cable jackets, NOT individually run ground wires. OP reports that his "sub?" Panel has no ground wires at all, yet ...


8

Yes, just be sure to run a 4 wire circuit (2 hots, neutral and ground), if the current garage is attached you don't need extra ground rods. In fact, since you are planning for the future, you might install a sub-panel now that would supply your EVSE outlet as well as other circuits in the future. As many others have said here, go bigger than you expect to ...


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