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39 votes

What type of cable should I bury for a small utility shed?

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 ...
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39 votes
Accepted

Half of house power voltage drops during storms

There are two tests you can do when this happens. Check the voltage of the good circuits. If their voltage is over 120V by an equivalent amount (e.g. 100/140V or 90/150V), that confirms you lost a ...
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30 votes

Can a 240V light fixture be used in the US with a 120V light bulb?

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 ...
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  • 14.5k
29 votes

Half of house power voltage drops during storms

Because it is a storm, this is almost certainly an outside your home problem, which almost always is a utility company issue. Because it is "half" and "intermittent", this is most ...
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25 votes

What type of cable should I bury for a small utility shed?

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 ...
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  • 20.8k
21 votes

Confusion over 220 and 230 volt outlets

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 ...
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  • 14.5k
20 votes

Which terminal to use on my multimeter

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 ...
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20 votes
Accepted

Why bother referencing neutral to ground in residential transformer?

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 ...
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19 votes
Accepted

Can I replace a bulb with one with more watt?

The wattage limit on a light fitting is related to the amount of heat generated by a tungsten bulb of that wattage. Putting a 60W bulb in a 40W or 25W fitting is definitely not recommended. However, ...
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  • 5,166
15 votes

Confusion over 220 and 230 volt outlets

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 ...
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14 votes

Can a 240V light fixture be used in the US with a 120V light bulb?

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 ...
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  • 526
14 votes

Is it possible to downconvert 30A/240V to 15A/110V by replacing a circuit breaker?

Well, first, you can't do work in a rental property without 2 things. Landlord's permission to do the work AND Local government permission to do the work, which will only happen if the work is a) ...
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13 votes

Can I replace a 115 V doorbell transformer with a 120 V doorbell transformer?

There are 3 issues here. The one in the title is actually the least of the concerns: 115V to 120V The US electric supply has gradually increased the standard voltage over the past century from 110V ...
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12 votes

Which terminal to use on my multimeter

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 ...
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12 votes

When running a bigger wire to deal with voltage drop on a 240V circuit, do I now need to run a neutral as well?

My question is now that I'm running a 30 amp wire and only using 20 amps, do I need to run a neutral to send the unused 10 amps back the supply? There is no 'unused 10 A'. However (and this is ...
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  • 584
10 votes

What type of cable should I bury for a small utility shed?

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 ...
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  • 107k
10 votes

Strange Voltage at Receptacle

Open ground somewhere. Digital multimeters are very sensitive and the tiniest of leaks can mislead you. Best to put some sort of small load (like a 25 watt incandescent light bulb, NOT LED) across the ...
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9 votes

When running a bigger wire to deal with voltage drop on a 240V circuit, do I now need to run a neutral as well?

There is no "unused" 10 amps. You use the #10 wire because it's big enough to handle the 20 amps without overheating and in your case, without dropping the voltage. If you are running ...
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  • 18.8k
9 votes
Accepted

Why is there voltage between the hot and traveler or other wires when all switches and fixtures are disconnected?

This is the normal confusing issue of voltages with very high source impedance. Also named phantom voltages, which may be a little bit confusing, since the voltage is completely real, but it can't ...
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  • 2,368
8 votes

When running a bigger wire to deal with voltage drop on a 240V circuit, do I now need to run a neutral as well?

A 30A circuit does not push 30 amps. It pushes 230 volts, and the appliance draws however much it needs. As such, no need to return any extra amps... they just won't be taken. The circuit breaker is ...
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7 votes

Electrical hook up for new stove top

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 ...
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7 votes
Accepted

Lights go dim with a moderate load imposed: how to troubleshoot?

Poke in wire connections on switches and outlets are notoriously failure prone. Whilst it may be practical to troubleshoot and find the worst connection in your room causing the voltage drop be aware ...
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  • 61.9k
6 votes

If using an old 240v cable to make two 120v circuits, is there a risk of overheating the shared neutral return?

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 ...
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6 votes
Accepted

How to determine if a light bulb is compatible with a lamp?

Those LED replacement bulbs are not a drop-in replacement for TL tubes. You will need to do a bit of rewire to the fixture to take the starter out of the picture. If you are uncomfortable with that ...
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6 votes

Why do I measure high and low voltage on a shop panel circuit?

Watch your tail! The grounds in the shop will be energized! This. This is why 3-wire feeders were outlawed in NEC 2008. Anytime a neutral wire breaks, it is pulled up to the voltage of a hot wire. ...
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6 votes

When running a bigger wire to deal with voltage drop on a 240V circuit, do I now need to run a neutral as well?

As others have said, there is no "unused" power to return. Think about it on a simple 15 amp 120v circuit: You plug a 100 watt lamp into it that uses just under an amp (old style ...
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6 votes

All wires in thermostat junction box have high voltage

There are two very different types of thermostats: Low Voltage These use low voltage, typically 24 volts from a transformer. Generally they use 18 AWG wire, though thicker wire is perfectly fine. ...
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6 votes

Half of house power voltage drops during storms

I've had a similar issue occur with one phase drooping at times. After calling out the power company they rapidly diagnosed it as a damaged transformer a block up the street. Once they replaced that ...
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  • 61
5 votes
Accepted

Temporary (multi-hour) voltage drop that seems instigated by running an appliance?

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.
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