Hot answers tagged

39

Why bury a cable when you can be future-proof? The primary issue with direct buried cables is that you have to dig them up in order to upgrade them, a costly proposition. Hence, it's a far better choice to spend the money to lay a couple of fat PVC conduits now and then pull wires through them, than to have to dig things up 5 years down the road because ...


30

Hard to say without details. If it is an incandescent lamp with a replaceable screw-in bulb, and the socket fits a bulb made for here and 120V, then yes, it shouldn't matter. But again, the devil is in the details. If we are discussing screw-in base bulbs, Europeans mainly use E14 and E27 bases. E14 is equivalent to what we in North America call a "...


25

I'm going to be a bit contrarian and say 10/3 UF. It's pricier and overkill for your existing setup, but here's why it could be worth doing it now. A single 12/2 means you only get 20 amps at your shed. Period. Next year, you buy some power tools and you start taxing your 20 amp. If the breaker pops, you get to walk back to your main panel. Pop it multiple ...


21

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 ...


20

Stay away from the 10A terminal. That is for amp measurements ONLY, and creates a dead short between the 10A terminal and the common. This will blow your fuse, burn up your probes, and/or destroy the meter. Never use that unless/until you know exactly what you are doing.


20

I know you're looking for a "tweet" of an answer, a simplistic reason "Oh, it's this". There's actually a lot to it. It's not an ideology, it's hard empirical data culled from a sea of accident reports. They are using field data to "min-max" for minimum casualties. What you're talking about is an isolated system. That is a ...


14

Answer is that probably you can, but you really shouldn't. Cables, switches and contacts inside the lamp are rated for specific voltage and current. You can go lower on both, but not higher. Ampers go up if you want the same power with lower voltage. For example , if your lamp accepts 60 watt light bulb at 240V, then cables etc are rated for 0.25A. Similar ...


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 ...


12

Keep in mind that using a meter that's not rated for the task can be dangerous! Even with relatively low risk things like residential receptacles. Right off the bat - if you got this meter for free with a purchase of a blue tarp at Horrible Freight, just throw it out. Next, make sure the meter is properly rated for the task. Meters have CAT ratings ...


10

I've built several such sheds, and a #12 UF-B (moisture and UV light resistant) cable (usually gray) is appropriate on a 20A breaker (or smaller). Depending on where you are it may need to be buried to a particular depth. Conduit is a good idea and may reduce the depth requirement. Otherwise, use your best judgement to prevent damage in the future. Because ...


7

You can keep the existing wiring and breaker Range loads are computed from their wattage, based on the rules in NEC's Table 220.55. In particular, since 422.10(A) paragraph 4 explicitly permits range loads to be sized as per Table 220.55: Branch circuits and branch-circuit conductors for household ranges and cooking appliances shall be permitted to be in ...


6

Actually, it would result in a net 0 A on the neutral. So this actually can work quite well and is called a Multiwire Branch Circuit or MWBC. The one catch is that the breakers powering the circuit need to be set up for common shutoff - i.e., if you turn off one, you always turn off the other. If the breakers are actually set up for common trip, which is ...


5

The issue was with the breaker at the service panel. I replaced the breaker with a new one and since then we've not had any voltage drops.


5

History of that dangerous socket When they started grounding things in the 1960s, the appliance industry asked for a "pass" on dryers and ranges connecting via NEMA 10 receps (hot-hot-neutral). They were afraid a compulsory conversion to the modern NEMA 14 series (hot-hot-neutral-ground) would result in customer confusion and lost appliance sales. ...


5

Just to expand the explanation in the answer from @manassehkatz: On a USA-type 240 volt circuit, you actually have two 120 volt hots, as you know, but the AC signal is 180 degrees out of phase. So when one hot is at +170 volts (peak voltage for 120 volts RMS), the other hot is at -170 volts and when one hot is at 0 volts, the other hot is also at zero. The ...


4

Volt meters are rated in mega ohms per volt. Most meters today are at least 1M ohm with many being 10M this so the meter won't load the circuit and provide an inaccurate reading. Since the impedance of the meter is so high it can detect voltage with almost no potential or what we call phantom voltage. There are low Z or low impedance meters out there that ...


4

Your dead phase is backfeeding via your 240V appliances. If your 240V appliances had 0 resistance, your dead-phase side would light up at full voltage. As things are, the 240V loads are in series with the 120V loads on the dead phase. That is causing the voltage to settle out where it is. You can manipulate that by turning on 240V resistive loads ...


4

Straight up You cannot afford to fall below 110V. Ok. Supply at your house is supposed to be 120V so we have a little room to play with. If you use 8 AWG cable, voltage drop will be limited to 8.29V on a full 20A load, giving 111.71V. That meets your criteria. If actual pulled amperage is less, voltage drop will be proportionately less, and ...


4

Adding transformers will not "stabilize" anything, I have no idea where you got that idea, but it's wrong. Sometimes people step up the voltage to a higher level (like 480V) and back down again for a long distance run so that the current is less, because less current results in less voltage drop since voltage drop is a function of I (current) Squared / R (...


4

If you go small - a single 20A multiwire branch circuit - you don't have to put a subpanel in at the shed. You will still want a disconnect, but they are cheap. At 100', 12/3 UF would do it. But then again, if you spend a few extra bucks, you could bury 8/3 UF instead of 12/3, and use it for that 20A multiwire branch circuit now, and have an easy ...


4

How dimmers work It sounds like you have some very common misconceptions of how dimmers work. The usual assumption is they reduce the voltage; however that would require either a) a Variac (about a 30 pound transformer bigger than a soda can), or b) a large power resistor about the size of a shoe box, that makes lots and lots of heat. That's not how it ...


4

6000W at 110VAC would equate to ~54.5A. It would be extremely unusual to see an 110VAC outlet supporting that level of current. You really need to show a picture of the outlet to allow members here to verify that this is a compatible outlet. A 55A circuit would require feed wires of at least 6 awg copper wire. You need to show evidence that the "really ...


4

Memory key: Because you want to measure voltage (V), use the VΩmA terminal. (Also use that terminal for measuring resistance (Ω) and small currents (mA).) The 10A terminal is special purpose, only for measuring very high current (up to 10 amps).


4

You've touched on the reason why electric utilities use high voltage for their distribution lines and also why you see transformers either on poles at your location or on the ground in a (usually) green box. They do this to avoid power loss in the wires which increases with the square of the current. Mathematically, you have: P = I^2 * R where P is power ...


4

Keep in mind that voltage drop in the wire is totally load dependent; when you measure voltage without load at the end of long wires, you won't see much if any voltage drop. If you use a splitter on the end of your chain of extension cords, and plug in your shop vac and turn it on, and test voltage on another receptacle on the splitter, you'll see voltage ...


4

Is that too many layers of things where it can be a problem safety wise? The number of "layers" isn't a huge concern, no. As long as each individual component is rated for the voltage and current that will be present, it should be fine. That said, you might not want to use this approach as a permanent solution. The travel adapters are useful, but ...


3

In Europe, there were various standards requiring either 220 V or 240 V in various places. Britain even had 250 V in some areas. This was all standardized to 230 V in the EU and surrounding areas (the European Network of Transmission System Operators) so they could be interconnected. Not much actually changed, as the voltages are all within acceptable ...


3

The voltage measured on the coax doesn't tell the whole story, especially if it's measured with a high-impedance digital multimeter. The two cable boxes will have isolated power supplies inside, meaning their low voltage circuitry is isolated from the high voltage mains. But there can be capacitive effects that would cause a voltage to appear between the ...


3

Sensitive voltmeters, including most cheapies, will read stray voltages where no voltage of importance is present. It is picking up stray EMF garbage from wires, radio, or you. Treat it like an idiot savant, write the numbers down and play them on a lottery ticket. That is probably the best use of such readings.


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