Understanding Electrical Power

These fundamentals we will apply to pop up campers. I wrote this cause I have seen a lot of questions on newsgroups pertaining to power consumption on a pop up camper.

There is five items we should address:

Voltage
Amperage
Wattage
BTU's
Wire Sizing

Almost all pop up's use a voltage of 120 volts and can plug into a 30 amp receptacle with a RV shore-line cord. This is normally connected to a power converter that converts 120 volts to 12 volts DC to operate lights and ect and even charges your RV battery.

In addition the converter contains normally 2 circuits of 120 volts to operate your appliances and outlets. DO NOT ALTER THE CONVERTER! I have heard of replacing the factory breakers with twin breakers so they can get two more additional circuits. I DO NOT RECOMMEND THIS! This will cause the converter to produce heat and will call for a early retirement of you converter.

Most converters have a 20 amp and a 15 amp circuit to power up your appliances. This will enable you to run 2 - 1500 watt heaters and some small appliances. A 13,500 btu AC and small appliances. One 1500 watt heater and water heater and very few small appliances. YOU CANNOT RUN 3 - 1500 WATT HEATERS! Just do your math and you can figure it out. Amperage is the key to unlocking the capacity of you pop up camper. Look at the following examples.

To Find Your Amperage

Divide your wattage by your voltage

Example:
1500 Watt Heater / 120 Volts = 12.5 Amps

1 - 1500 watt heater draws 12.5 Amps
This will work on either a 15 or 20 amp circuit.

2 - 1500 watt heaters draws 25 Amps
This situation you will have to run both on separate circuits. One on the 15 amp circuit and the other on the 20 amp circuit.

3 - 1500 watt heaters draws 37.5 Amps
This application will not work! Unless you add a new circuit.

Remember This (Great Information)

1 Watt = 3.412 BTU's
A 1500 Watt Heater = 5,118 BTU's

Wire sizing is another issue everyone should know.

15 Amp circuit use a #14 wire
20 Amp circuit use a #12 wire
30 Amp circuit use a #10 wire

Circuit breakers protect the appliance and ect. But the real purpose of the breaker is to protect the wire size. Example: A 30 amp breaker on a #14 wire could cause the wire to heat up and cause a fire before the breaker trips. Always protect your wire size with the proper amperage breaker. This applies at home as well.

DC Voltage Information

DC voltage flows in one direction only, while AC voltage flows in both directions (Example: 60 cycles) which means it has a return path of 60 times per second.

With DC voltage flowing in one direction there is a lot of voltage drop in the length of the wire. Now without getting tech'ky about this, use the following guide line to assure proper voltage at the source. This will give you the max wire length for proper voltage. I will be posting this on our website in a better format. This is a good guide line but sometimes you have to cheat.

Amperes	Wire Size	Length in feet
2.0	14	35
	12	56
	10	90
5.0	14	15
	12	24
	10	38
10.0	14	7
	12	12
	10	19

I did not write any of the above information. All electrical infomation was provided by Pop Up Camping in North Carolina
(http://members.tripod.com/nccamper/id15.htm)

Modifications - Backup Lights