Generic electrical question Do volts drop when a load is on the circuit

[hombrewdude]

I have one of these Kill A Watt meters.

In the socket it is showing 120volts I put a load on it, that is about 5 amps. I would not think the volts should drop to 118?

Does this make sense?

[Toller]

It is called voltage drop. Your cable has resistance, so it uses up some of the energy.

[homebrewdude]

The reason why I bothered to check...

We are having storms high wind in my area now. The lights flickered like the power was off. But this one particular circuit was actually off (my fish tank)

Could I have had a voltage drop in my entire house, then compounded with the fish tank draw cause it to go out?

[Nate Nagel]

is this a very long run?

nate

[homebrewdude]

Not really..

I ran 20 amp service about 50 feet

Nate Nagel wrote:

[dpb]

What size wire?

--

[homebrewdude]

12 gage

dpb wrote:

[homebrewdude]

I really messed that up...

I ran 20 amp on another project.

My basement and garage were on the same breaker. I ran wire to isolate the basement from the garage. Now they are on their own 15 breaker.

The basement service with the fish tank is probably pulling 10 amp at full load. Fish tank, lights and TV

homebrewdude wrote:

[Toller]

Most unlikely. The voltage drop is pretty constant, unless you have a large motor go on and it spikes. But it can't trip a circuit breaker or damage a circuit. (it can damage a motor, but that's another story.) More likely you had some voltage transients hit you with the storm. They could easily trip a GFCI or less likely a circuit breaker. I would look around for GFCIs that have to be reset.

[Terry]

I don't think the distance had anything to do with the breaker tripping. If it only happened once I would not sweat it.

I can't think of a scenario where a storm could trip an individual breaker unless lightning directly hit something on the circuit.

A 5 amp load can cause that much dr>I really messed that up...

[homebrewdude]

The breaker never tripped.

The power dropped and lights went out, pumps turned off.

But all the other lights and TV stayed on.

All on one breaker, which did not trip.

Terry wrote:

[Beachcomber]

Voltage drop means the whole overall circuit will be drawing less current , not more (due to the added resistance). If the voltage gets too low, you might have problems with dim bulbs and a slow-to-heat fish tank, but it sounds like you are not there yet.

If you continue to add load, you will be drawing more current and may reach the tripping point of the breaker. (It may not be exactly 15 amps). The reason it trips can be a complex function involving time, thermal delay, and factors like surge intensity. Residential circuits are usually derated to 80% of the breaker rating for maximum continuous load.

If the breaker is a GFCI breaker, it might trip for apparently no reason at all. Usually, though it is caused by actual leakage to the ground circuit. I've also had several trips due to nearby lightning strikes, but the new GFCI's are supposed to be better for this.

[bud--]

Voltage drop on a 15A circuit (#14 wire), 50 feet of Romex, is 3 volts.

[hallerb]

simple most homes are 220 volt breakers are fed from both sides of power line.

A supply transformer up the street fried once knocking out one side of the line, while the other side continued to work fine.

thats probably what happened to you, power company breaker on transformner tripped knocking out that outlet and others you hadnt noticed, then reset.......

its happened here once and can be very confusing

[Stormin Mormon]

Voltage drops when a load is applied. Yes, that's how it happens. In flash lights, automobiles, and appliances. More load, more voltage drop.