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 !!!

[krobbe]

If measuring voltage on the same 15amp circuit that the 12.5amp elect heater is plugged into, there will definitely be voltage dropped on that circuit. A 15amp circuit that uses #14 wire and has several receptacles between the heater and the circuit breaker is a hazard unless all the receptacles are wired pigtailed. The common method of wiring receptacles in RVs as Myredracer shows uses a 2 piece compression receptacle that has very little contact surface with the wire. Under high loads(heaters) the small contact area gets hot causing metal expansion and loose connections which then causes even more heat. People, these outlets are JUNK! I've replaced mine with 20A with screw and pinch plates and wired them using pigtails.

[dougrainer]

BobnSofi wrote:
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

AS I STATED--- those meters are NOT accurate. The ONLY thing they are good for is to indicate you have AC volts in the RV. I had a customer come in years ago and he was upset because on Genset his voltage was dropping to 105 volts. My $200 Fluke meter showed he had 119 volts at the same plug that POS meter was plugged into. Doug

[myredracer]

IMO as an EE, it's not the RV "SCD" type receptacles that are a problem. They have to meet extremely rigorous testing under UL requirements. And they can't be worse than the commonplace residential receptacles where you push a stripped wire into a hole in rear of it.

The bigger issue is the wiring and installation done at the RV factories. Below is a photo of a receptacle I removed from a previous TT. Not the only one I've seen similar to that in 3 TTs we've owned. Note that there are two "prongs" that the wires are supposed to be pushed down into and the hot wire is only pushed onto one of the prongs/stabs. One of the prongs was damaged. This means that this particular receptacle would only be able to carry 1/2 of it's 15 amp rating. Imagine having a 1500 watt electric heater plugged into it and running continuously for extended periods. A fire waiting to happen...

There is a proper tool for terminating the wires on RV receptacles and they are expensive so either the installer doesn't have one or doesn't have it with him and uses a screwdriver or pliers instead. I doubt the guys installing these are licensed electricians too. Inexcusable...

[MrWizard]

What you say is true of many RVs

But the Safari we had and the Bounder we have now, have screw on outlets
With the wires screwed on
Not pushed in

[wa8yxm]

That is a SERIOUS voltager drop.. But as I said the outlets (Save for the GFCI itself) in an RV. are NOT high current devices. oh they are rated for 15 amps but the resistance where the wire is connected is too high due to the knife edge type connection.. WHich is why I have dedicated outlets with 12ga wire BENT AROUND A SCREW for my space heaters.. Oh the 15/20s are a different color (Brown on my rig) so as to make them clearly "Different" from the off-white jobs the factory installed.

[myredracer]

Dusty R wrote:
Last I knew the National Electric Code states that from the meter to the main panel the Voltage Drop shall not be more than 3%. And from the panel to the furthest outlet the VD shall not be more than 3%. And from the meter to the furthest outlet the VD shall not be more than 5%.

Interestingly, the NEC says it's a recommendation, not a requirement. That's one big reason we see such large voltage drops in CGs. You can find a discussion on the Mike Holt forum here. In comparison, the Canadian electrical code (CEC) specifies voltage maximum allowable voltage drops, not recommendations.

Power companies have to comply with ANSI C84.1 and provide voltage within certain limits. Explanation here. Service voltage can get down to 104.4 volts (on 120 volts nominal) and still meet regulatory requirements, and that's before considering voltage drop under the NEC.

[stevenal]

BobnSofi wrote:
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

You have a resistive leg. The problem could be in your RV, cord, plug, 50 A receptacle you're attached to, breaker feeding the receptacle, etc.

You say you are full timing. In one place, or does the problem show in multiple locations?

Might want to avoid using a receptacle that causes the drop until it's fixed, since some heating is occurring at the resistive point.

[road-runner]

As dougrainer stated a couple of pages ago, the plug-in analog meters are not accurate. I consider the readings from them close to worthless, and would not base any conclusions on them. It's not an analog-vs-digital meter thing. It's just that most plug-in analog meters have lousy accuracy. Use a digital meter, or a good analog meter.

[MrWizard]

10 volt drop for one heater, on one leg of 50 amps , with the meter on a different circuit breaker, seems like too much

He said he was using the 50 amp service, he did not say it was a 50 amp RV

MrWizard wrote:
Op is your rig 50 amp

Or are you using a 50/30 adapter on a 30 RV

If so that explains the voltage drop

If your RV is 50 amp, there is a problem someplace
Could be your shoe cord or the pedestal socket

OP indicated 50A and he figured out what was going on 4 posts up.

Cheers,
Scott

[DrewE]

Hmmm...so there's maybe about a 9V drop on just that circuit when using the heater.

I would strongly suggest unplugging the RV temporarily, opening the breaker box (and the inner cover so you can see all the wires), and checking that all the screws are snug and the wires do not show signs of overheating. It seems like there is excess resistance somewhere on at least one of the circuits, and that generally means a bad connection or bad wire somewhere, and heating due to the power the poor connection or conductor dissipates.

If the heater is using about 12A (roughly typical on high), and the voltage drop is at a single connection, then there is around 100W being dissipated at that point. That's a lot of localized heating, as anyone who has touched a hot 100W light bulb knows.

[Dusty_R]

Last I knew the National Electric Code states that from the meter to the main panel the Voltage Drop shall not be more than 3%. And from the panel to the furthest outlet the VD shall not be more than 3%. And from the meter to the furthest outlet the VD shall not be more than 5%.

[wa8yxm]

A Couple of things
First ANY load will cause a slight voltage drop. HOW slight depends on the size of the wire (Starting with the winding on the power company transformer, the wire down the pole or out of the ground to the park meter. the wire from the meter to the distribution panel and from there to your site.

Also the length of those wires
The condition of the plugs outlets and connections

And of course the size of the load.. Seeing a drop when sucking 12 amps is not uncommon HOW BIG A DROP matters Some places I've been it is scary.

Next: What worries me about your post
You mention plugging space heaters into your RV.. The odds are the outlet boxes in your Rig are Uni-box style.. In this type of outlet box instead of bending wire around a well tightened screw They push the still insulated wire down in a "Wedge" that slices through the wire and makes a KNIFE EDGE connection with the wire.. 10 amps (Space heaters are 12.5) is a lot of current to pull through that small a contact.

I smelled hot wire
Others have posted photos of even hotter (As in melted) wires

I installed some 15/20 amp outlets 12ga wire stripped back and bent around a well tightened screw.. Each of these outlets has a dedicated circuit breaker (Either 15 or 20 amp) also I added a kitchen circuit. other than the outlets (And breaker) are 15 amp type still 12ga wire bent around a screw.. Less voltage drop. NO overheating of wires.

[ScottG]

MrWizard wrote:
Op is your rig 50 amp

Or are you using a 50/30 adapter on a 30 RV

If so that explains the voltage drop

If your RV is 50 amp, there is a problem someplace
Could be your shoe cord or the pedestal socket

OP indicated 50A and he figured out what was going on 4 posts up.

Cheers,
Scott

[MrWizard]

Op is your rig 50 amp

Or are you using a 50/30 adapter on a 30 RV

If so that explains the voltage drop

If your RV is 50 amp, there is a problem someplace
Could be your shore cord or the pedestal socket