Electric Heater lowers Voltage ??? HARMFUL ???

[BobnSofi]

Hi All,

we are full timing and use and electric space heater. This causes a voltage drop (according to the cheap voltage meter plugged into a bathroom outlet).

The space we are in has 50amp, 30amp, and two 15amp. We are plugged into 50amp.

Of course, we do not want to hurt our RV.

So...

How do you all pros handle this perceived voltage drop occurring when using an electric space heater?

??? Is this an actual problem ???

Alternative suggestions of using the A/C heat pumps, or LP furnace are obvious, thus not needed.

!!! Thanks in Advance !!!

[time2roll]

110+ is fine. However I would not implicitly trust that meter. Get a regular hand held digital meter.

Need to check voltage to neutral on each of the main breakers. If voltage drops on one side and rises on the other you have a poor neutral connection. If voltage just sags or hangs steady you may have a loose hot connection. Look for evidence of heat in the breaker box. Need to remove the cover to see the wires connected to the breakers and bus. OK to just check and snug them all up tight. Also check for heat or connection issues in your transfer switch.

[ScottG]

myredracer wrote:

road-runner wrote:

ScottG wrote:

50A is also single phase 😉
It's split phase Discription

From the wikipedia link:

"This results in two 120 V AC line voltages which are out of phase by 180 degrees with each other." (Sounds like 2 phases to me.)

"Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system."

Contradiction? That's because "two-phase system" has a formal definition of 2 phases being 90 degrees apart. Split-phase has 2 phases 180 degrees apart. So while split-phase can't be called two-phase, it's not single phase either. It's a supply that has 2 phases and it's called split-phase.

A 120/240 volt system is always referred to as single phase and never as having phases. In power systems, there is either single phase or 3-phase systems (as in commercial/industrial systems), never "two-phase". In 3-phase systems, it is very important to understand the phases of conductors because it affects things like motor rotation but switching the two hot legs on a 120/240 system isn't all that important.

A 50 amp service in an RV or a 200 amp service in a house are identical except for current rating. In the electrical industry these are referred to simply as 120/240 volt, single phase. There is Line 1 and Line 2 and a neutral (grounded). L1-L2 is 240 volts and either L1 or L2 to neutral (or ground) is 120 volts.

Phasors, or more correctly phasers, only exist in Star Wars movies. People should stop going to Wikipedia or Google on this stuff.

jkwilson wrote:
That's because people use different definitions of the word phase.

To an engineer or a technician, there are two phases on the user's side of the transformer because they use the term phase to describe the timing relationship between the sine waves.

If you're talking about an ordinary 120/240 volt system, strongly disagree.

Sorry but I have to disagree as well (and I was both a tech and an EE). There is only one defintion of phase; a 120/240 system is always a split singe phase and never two phase. The two sides of the phase are 180 out from each other or you could think of them as a continuation of each other. Or another way to think of it is that it's one signal that's devided. Wiki's wording is imprecise.
As was already pointed out, there is no 2 phase power in the USA.

OP, I would use a digital meter to verify what your analog meter is telling you.

[BobnSofi]

before and after below

The good news is I looked around and found a plug on a different breaker, and turning the heater on, on a different breaker, did not alter the volt meter reading at all.

We would have never known this was happening, except we keep a volt meter plugged into a bathroom plug at all times

[Chris_Bryant]

On a 50 amp rig I wouldn't like to see a voltage drop with just a heater. The only way a small drop would be acceptable is if the meter is on the same branch circuit, and even then it would have to be small.

It's a matter of finding where you are loosing the voltage.

[road-runner]

Split-phase power cannot be called 2-phase because that name has been defined to mean something else. If you want to argue that split-phase power is single phase, then by applying the exact same logic, you're arguing that 6-phase power is incorrectly named. 6-phase power can be derived from 3-phase power exactly the same way split-phase is derived from a single phase, yet it's not called split-3-phase. It's called 6-phase because that's what it is, and the name wasn't taken beforehand to mean something else.

[myredracer]

road-runner wrote:

ScottG wrote:

50A is also single phase 😉
It's split phase Discription

From the wikipedia link:

"This results in two 120 V AC line voltages which are out of phase by 180 degrees with each other." (Sounds like 2 phases to me.)

"Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system."

Contradiction? That's because "two-phase system" has a formal definition of 2 phases being 90 degrees apart. Split-phase has 2 phases 180 degrees apart. So while split-phase can't be called two-phase, it's not single phase either. It's a supply that has 2 phases and it's called split-phase.

A 120/240 volt system is always referred to as single phase and never as having phases. In power systems, there is either single phase or 3-phase systems (as in commercial/industrial systems), never "two-phase". In 3-phase systems, it is very important to understand the phases of conductors because it affects things like motor rotation but switching the two hot legs on a 120/240 system isn't all that important.

A 50 amp service in an RV or a 200 amp service in a house are identical except for current rating. In the electrical industry these are referred to simply as 120/240 volt, single phase. There is Line 1 and Line 2 and a neutral (grounded). L1-L2 is 240 volts and either L1 or L2 to neutral (or ground) is 120 volts.

Phasors, or more correctly phasers, only exist in Star Wars movies. People should stop going to Wikipedia or Google on this stuff.

jkwilson wrote:
That's because people use different definitions of the word phase.

To an engineer or a technician, there are two phases on the user's side of the transformer because they use the term phase to describe the timing relationship between the sine waves.

If you're talking about an ordinary 120/240 volt system, strongly disagree.

[jkwilson]

MrWizard wrote:
50 amp is 230vac Single Phase
Two hot legs one neutral, standard residential service

(technically 120v is split phase, only one leg of the power that is coming to your house)

Industrial / Commercial 3 phase uses three Hot Legs and NO NEUTRAL
There is no such thing as two phase power in the USA

This discussion comes up almost every time somebody mentions 50 service

That's because people use different definitions of the word phase.

To an electrician or power company worker, the 120/240 is a single phase even with the center tap for the neutral because they use the term phase to describe the service that the power provided to the customer is derived from.

To an engineer or a technician, there are two phases on the user's side of the transformer because they use the term phase to describe the timing relationship between the sine waves.

Having fixed phase relationships is critical to a power grid, so the idea of variable timing relationships seldom enters a lineman's world. Except at generating stations.

BTW, on 3-phase Wye circuits, there is a neutral created from the joining of the phases. Often referred to as a virtual neutral, it can do some bizarre things when the load becomes unbalanced. You'd be amazed at the amount of smoke created when a large motor winding fails.

[MrWizard]

50 amp is 230vac Single Phase
Two hot legs one neutral, standard residential service

(technically 120v is split phase, only one leg of the power that is coming to your house)

Industrial / Commercial 3 phase uses three Hot Legs and NO NEUTRAL
There is no such thing as two phase power in the USA

This discussion comes up almost every time somebody mentions 50 service

[rk911]

BobnSofi wrote:
Hi All,

we are full timing and use and electric space heater. This causes a voltage drop (according to the cheap voltage meter plugged into a bathroom outlet).

The space we are in has 50amp, 30amp, and two 15amp. We are plugged into 50amp.

Of course, we do not want to hurt our RV.

So...

How do you all pros handle this perceived voltage drop occurring when using an electric space heater?

??? Is this an actual problem ???

Alternative suggestions of using the A/C heat pumps, or LP furnace are obvious, thus not needed.

!!! Thanks in Advance !!!

what was the voltage before and after running the heater. nominal voltage is 120 +/- 10% or 108-132 volts.

[2oldman]

Your turn OP.

[time2roll]

BobnSofi wrote:
??? Is this an actual problem ???

Voltage 110+ is fine. When you see 105 or less please give another post.

[DrewE]

ScottG wrote:

DrewE wrote:

Of course, the 30A and 20A receptacles in the campground power box are only single phase, so measuring the voltage at them only checks one of the two legs. Often they are wired to opposite legs so checking both can verify both legs, but I'm sure that's not universally the case.

50A is also single phase 😉
It's split phase Discription

You're right. I should have written "single leg."

[road-runner]

ScottG wrote:

50A is also single phase 😉
It's split phase Discription

From the wikipedia link:

"This results in two 120 V AC line voltages which are out of phase by 180 degrees with each other." (Sounds like 2 phases to me.)

"Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system."

Contradiction? That's because "two-phase system" has a formal definition of 2 phases being 90 degrees apart. Split-phase has 2 phases 180 degrees apart. So while split-phase can't be called two-phase, it's not single phase either. It's a supply that has 2 phases and it's called split-phase.

[naturist]

Everything you might plug in causes a voltage drop. The larger the draw and the smaller the wires or poorer the connection to the mains, the larger that drop will be. If you plug a single LED light (very small draw) into a circuit capable of carrying 50 amps, that drop will be undetectable with any voltmeter. But if you put an electric space heater (large draw) on a 15 amp circuit with corroded plug or slightly burnt receptacle, you will easily find a significant voltage drop.

Whether the drop is significant of a problem, however, is another matter.

[myredracer]

If you knew how poor the workmanship can be when they wire outlets at the factories, you'd definitely want a dedicated outlet when running heaters for extended periods.

Cords on 1500 watt/15 amp portable heaters are often only 16 gauge wire (and meet UL). Do not coil the cords up and/or hide them under carpets or they can overheat. Follow the heater's clearance requirements.

Low voltage is very common in the summertime from many RV-ers in a CG running AC units and how low the voltage gets depends on a few factors, including how old the CG is and how it was wired. Low voltage won't hurt an electric heater but it will lead to damage in AC units.

Note that the heat output of an electric (resistive) heater varies as the square of the voltage as per Ohms Law, based on a nominal line voltage of 120 volts (the industry standard). Say the voltage got down to 104 volts, the point at which an EMS will cut you off, the heater output would be down to 104/120 x 104/120 = 75% of it's rating. If it seems like you aren't as warm as you'd expect, it could be the voltage is getting rather low. Plugging in or turning on another heater may only cause each heater put out even less heat (from more voltage drop).

The condition of a pedestal can also be a factor in voltage drop. 50 amp pedestals are generally in much better condition than 30 amps though. A 50 amp RV should not have a problem with a couple of plug-in portable electric heaters as far as the 50 amp service goes. Your AC units probably draw as much current and maybe more. There can also be some voltage drop on the wiring from your panel inside to a receptacle. Having a permanent voltmeter mounted inside is always a good idea so you can keep tabs on voltage at any time. There are some good plug-in LED ones or install a hard-wired type. An EMS is a good thing to have and will automatically protect you against low voltage (and a few other anomalies).

If doing a lot of RV-ing in cold weather and you want to use electric heat, there are several options for installing permanently mounted electric heat. I installed 2 KW of permanent electric heat in our TT which is 30 amps but I also installed a custom demand controller. If you are coming across CGs with low voltage, you can always use an autoformer to boost the voltage.