40 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 ...
ThreePhaseEel's user avatar
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 ...
Harper - Reinstate Monica's user avatar
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 ...
JRaef's user avatar
  • 15k
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 ...
manassehkatz-Moving 2 Codidact's user avatar
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 ...
Machavity's user avatar
  • 24.7k
24 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 ...
JRaef's user avatar
  • 15k
21 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 ...
Harper - Reinstate Monica's user avatar
21 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 ...
Harper - Reinstate Monica's user avatar
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, ...
Tetsujin's user avatar
  • 11.5k
19 votes

Why does my tankless water heater fail when the HVAC is running?

In the words of Captain Kirk, We need more power! Update cancelled because OP commented that they have now verified the manual actually calls for 2 x 60A. All other issues of total load capacity still ...
manassehkatz-Moving 2 Codidact's user avatar
16 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 ...
ThreePhaseEel's user avatar
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 ...
Mołot's user avatar
  • 537
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) ...
Harper - Reinstate Monica's user avatar
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 ...
manassehkatz-Moving 2 Codidact's user avatar
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 ...
batsplatsterson's user avatar
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 ...
Neil_UK's user avatar
  • 583
11 votes
Accepted

Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2?

TL;DR 208V System This is characteristic of 3-phase power distribution. It is very common in large commercial and industrial use, and also in apartment buildings in many places. The typical numbers ...
manassehkatz-Moving 2 Codidact's user avatar
11 votes

220v Washer Dryer Machine Voltage Tolerance

I think you're doing it the hard way. Areas which are 127V nominal, choose that voltage for a very specific purpose: when you configure your power supply as 3-phase "wye", with 127V any ...
Harper - Reinstate Monica's user avatar
10 votes
Accepted

Why does one phase of my buildings mains line show a significant amount of voltage (~60V) when it goes down?

Most all residential power feeds in the USA are 120/240 Vac split-phase. You have two hot wires (L1, L2) and a neutral coming into your house or apartment or trailer. After passing through your power ...
Sparky256's user avatar
  • 226
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 ...
isherwood's user avatar
  • 137k
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 ...
George Anderson's user avatar
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 ...
jay613's user avatar
  • 37.4k
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 ...
xeeka's user avatar
  • 2,548
8 votes

How to protect house hold electric appliances from mishaps

Go through your house with a fine-tooth comb and make sure every aspect is fully compliant with modern European electrical codes. No exceptions. The classic thing in the developing world is shoddy ...
Harper - Reinstate Monica's user avatar
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 ...
Harper - Reinstate Monica's user avatar
8 votes

Is it possible to convert a (US) 240V 20A outlet into a single 120V 20A outlet using an adapter cable?

It should work as long as the 240 VAC outlet has neutral connected and the correct wire gauge. Some only have the two hots and ground. A four wire one should have both neutral and ground. This is ...
GodJihyo's user avatar
  • 181
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 ...
ThreePhaseEel's user avatar
7 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 ...
manassehkatz-Moving 2 Codidact's user avatar
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 ...
Michael Karas's user avatar
  • 64.6k
6 votes

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

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 ...
DoxyLover's user avatar
  • 12.6k

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