Community Forums

schupaul · 09-21-2010, 06:22 AM

Well long story short, I had and exsisting spot I was going to put an 30A outlet for the RV but come to find out the Wire in that conduit it Service entrance wire and is not suitable. As a result I need to add and outlet on the other side of the house directly behind the main panel on the outside of the house. In doing this I will have to use either a 50ft + a 30ft 30A extention cords. I checked the voltage drop and it says that it will be at 7 volts. Is this going to harm my RV?

GaryKD · 09-21-2010, 06:50 AM

Hi schupaul,
Assuming the 7 VAC drop is correct, the short answer is no, it will not harm your RV. That being said, there are some things one needs to consider.

1. Is the incoming voltage 120 VAC?
2. Is it marginal or strong 120 VAC?
3. The important consideration is the WATTS you'll be using. Appliances will draw their rated WATTS or die trying. If the WATTS usage goes up and the VAC goes down then the AMPS draw must go up. This creates heat and stress on the electric system components making the power draw.

If the WATTS usage is monitored and controlled, you should be okay.

RJay · 09-21-2010, 07:08 AM

You should also add another 1 or 2 volts voltage drop for the wiring in the coach before the power ultimately reaches the appliances.

schupaul · 09-21-2010, 08:37 AM

I guess the watts would be strong. I have to put the outdoor plug box right on the outside of the garage behind the main electrical panel in the garage. Due to the way this 2 story house was constructed running wire all the way to the house just wouldn't be worth it and cost prohibative. The run from the Main box circuit breaker to the outlet would be not more than 3ft.

schupaul · 09-21-2010, 08:40 AM

I would be mainly running just the A/C and the fridge in the RV for about a day or so at a time. The way my driveway and alley are it makes it impossible for me to get a 30 footer in my rear driveway. As a result I am forced to pull it in front of my house the night before using it to load up and let the fridge cool down.

Gary RVRoamer · 09-21-2010, 03:08 PM

A drop of 7 volts may or may not be a problem, depending on what voltage it starts out at. A 7 volt drop from 120 is fine, but a 7 volt drop from 110 is a problem for air conditioners. You need to end up at the coach with at least 108-110v.

schupaul · 09-22-2010, 04:08 AM

I will check the voltage at the termination point. If it is low, how would I go about bumping it up?

Route 66 · 09-22-2010, 05:10 AM

As noted in previous posts anything below 108v is not advisable. The accepted tolerance for 120v is +/- 10% which is 108v.

If you have low voltage to start with, once a load is added the voltage could drop to an unacceptable level.

The easiest way to reduce voltage drop is by using a larger gauge wire.

The other option is a voltage booster.

frankdamp · 09-22-2010, 10:30 AM

Couldn't you run outside conduit from behind the breaker box to where you'd origially planned to put the outlet? That way you could use heavier gauge, solid conductor Romex wire instead of the thinner, stranded wire that extension cords usually have and get a minimal voltage drop.

Luv2go · 09-22-2010, 10:55 AM

Quote:

Originally Posted by schupaul

Well long story short, I had and exsisting spot I was going to put an 30A outlet for the RV but come to find out the Wire in that conduit it Service entrance wire and is not suitable. As a result I need to add and outlet on the other side of the house directly behind the main panel on the outside of the house. In doing this I will have to use either a 50ft + a 30ft 30A extention cords. I checked the voltage drop and it says that it will be at 7 volts. Is this going to harm my RV?

How about putting a 50A outlet in and running 50' of 50A extensions? This way you don't have the voltage drop. Of course the cords cost a lot more.

Stewart

Always-RVing · 09-22-2010, 11:45 AM

Heavy Duty 30-amp 10/3 STW Cord, 50

10 awg copper, 30 amp rating, 50 ft Heavy Duty

Voltage Drop Calculator

At maximum load 30 amps.. The drop is only 3.6 volts

Luv2go · 09-22-2010, 12:35 PM

Quote:

Originally Posted by Batman_777

Heavy Duty 30-amp 10/3 STW Cord, 50

10 awg copper, 30 amp rating, 50 ft Heavy Duty

Voltage Drop Calculator

At maximum load 30 amps.. The drop is only 3.6 volts

Yes, I believe the 7V comes from about 100' of 10ga wire, that is 50' ext. cord + 30' ext cord + 20' from the power cord of schupaul's coach. He did mention that he was using a 50' plus a 30' cord, though you could read his post the other way.

If he use used a 50A (6AWG) cord for the first 50', voltage drop would be 1.4V + 3.6V = 5V. If he used 50A cord for the first 80', 2.3V + 1.4V = 4.7V. Either case is better if his line voltage is marginal with a 30A load.

Stewart

schupaul · 09-25-2010, 06:44 PM

OK. Is something wrong with my multimeter. Here are the reading that I got.

Right at the outlet which is 2ft of wire from the main box = 166.6
With a 50ft 10/3 extention plugged in= 166
with another 30ft 10/3 extention added=166.

These are the reading before even plugging in the RV to the extiontions.

Shouldn't I be getting 120 +/- on the multimeter. By the way, I have a HF digital one. I am thinking maybe something is wrong with it????

jwomack · 09-25-2010, 08:26 PM

you are reading peak-to-peak voltage. set your meter to read rms. you will not read any voltdrop until you put a load on the conductors. voltdrop is the product of current flowing in the circuit times the resistance (more precisely the impeadence) of the circuit conductors.