Way to readily calculate amps?

TallTex

Member
Hi, folks! New to Heartland, and new to this forum. We just got a Caliber 265RLS, and had our shake-down voyage last weekend. Trailer has 30-amp service. Had air conditioner (AC) and refrigerator on electric; when I also turned the water heater on (with electric), the circuit breaker blew.

Called the dealer, talked with Service. Was advised that we need to run the AC on electric, the refrigerator & water heater on gas, as the AC alone takes 13 amps and the various other electrical systems (like the CD/DVD player) draw some amps even when not "on," so the amps add up rather quickly.

My question: is there a listing somewhere of what amperages all the things in the interior use n their "on" and "off" states, so I can maybe calculate what things I can use with what, without exceeding the 30 amps? I may have missed it in all the paperwork, but I didn't see a summary anywhere.

Thanks!
 

cookie

Administrator
Staff member
TallTex, welcome to the forum. And congrats on your new Caliber 265RLS.
You will need to calculate you current draw to find out how many amps you are using. Keep in mind that the AC has a start up draw as well as running draw.
Look on each item that you want to use and there will be a tag stating how many watts it uses. For example, look under your coffee pot or on a hair drier. They both draw considerable wattage. My coffee pot here draws 900 watts which is more than half of what your water heater draws at about 1,400 watts. Small items can use large amounts.
To calculate the amp draw, divide watts by volts and that will give you amps.
A water heater using 1,400 watts, divided by 120 volts would draw 11.6 amps.
You will have to find out how many watts your AC uses at start up and at run, then do the math.

Peace
Dave
 

57chevyconvt

Well-known member
In the Heartland Owners manual, i.e., Big Horn Manual, there is a section titled 'AMP Usage' that list the components such as A/C, water heater, Microwave, and their corresponding amp draw. Some of the users as noted: 15k A/C unit - 15 amps, water heater - 12 amps, Microwave - 15 amps, refigerator - 3.5 amps. I added an additional starting capacitor to my A/C unit to help reduce the in-rush volts/amp draw each time the A/C unit starts. You can find this modification at "ModMyRv.com. As noted in previous post reply, Ohm's Law is Watts=Volts X Amps; Amps = Watts divided by Volts.

I made me a chart of all the installed components and their amp draw, attached it to the inside surface of the door that covers all the lighting panel switches. This is quick reference for both wife and myself to review when we need to add additional items that use electricity. Also be aware that many of the older RV parks have poor, if any, maintenance on their electrical outlet post connectors. I try to keep my male plug stabs clean using fine grit sandpaper and dielectic grease (purchase at any auto parts store). Additionally, prior to setting up in a RV spot, I look at the electrical post box and inspect the female plugs. If it show to be discolored from excessive heat, I generally move to a different spot. A lot of the ware and tare of the female plugs come from people plugging in there RV cord with the breaker turned on and the A/C plus other uses are also turned on. This means that the male and female portions of the connection is the potential source of arcing, not so good over time.
 

WilmanJim

Well-known member
R stands for resistance measured in ohms
I stands for current measured in amperes
E stands for voltage measured in volts
P stands for power measured in watts

Ohmslaw.jpg


I've used this for over 40 years.
Jim
 
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