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Want to monitor Trailer amp draw on my 50 amp. 5er


Ed ke6bnl

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I go to a lot of 30 amp. campgrounds and want to monitor the amps to keep them under the 30 amp max of the panel.

I am going to put an AMP meter with a inductive coil

 https://www.ebay.com/itm/AC-Digital-Ammeter-Voltmeter-LCD-Panel-Amp-Volt-Meter-100A-300V-110V-220V-New/182728925264?ssPageName=STRK%3AMEBIDX%3AIT&var=690045695923&_trksid=p2057872.m2749.l2649

I order two of them one for L1 and L2 leg of the 120 volt. BUT my question is can you put one induction coil around both L1 and L2 wires to get the total amp draw of the trailer. 

2000 National RV Sea Breeze 5th wheel 30ft.

So.California

1950 F1 street rod

1949 F1 stock V8 flathead

1948 F6 350 chevy/rest stock, no dump bed shortened frame.

1953 chevy 3100 AD for 85 S10 frame

1968 Baha Bug with 2.2 ecotec motor 170 hp, king coil-overs,etc

1970 Baha Bug wihg 2332cc, King coil overs and everything else there is.

1998.5 Dodge 2500 4x4 Cummins, turbo, trans, injectors, lockers, bigger turbo,edge EZ upgrades for towing 35" BFG's, air dog lift pump etc.

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Yes, you can when you're plugged into a 30 amp socket so the two hot wires are in phase with each other.  When you're plugged into to a 50 amp 240 / 120 volt socket the two hot wires will be out of phase and you'll read the difference between the leg currents ... which is the same as the neutral current.

Don't ask what happens if the campground is sending you two legs of a 208 / 120 volt wye feed ... the math becomes more complicated than what I can do on my fingers.  :rolleyes:

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There is little need to be exact to keep below 30amps.

Only use 2 high current devices. 

--  air conditioner plus microwave, or water heater, or toaster.

You can still run your TV, computers or such.

Or you could install a surge protector which will also monitor your total amps, display the amps on the remote and keep your RV safe with this:  https://www.amazon.com/Progressive-Industries-HW30C-Electrical-Protection/dp/B002UC6RSA/ref=sr_1_5/141-0908316-8726314?ie=UTF8&qid=1508965832&sr=8-5&keywords=progressive+rv+surge+protectors

I am assuming you have a 30amp RV since you have a 30' 5th wheel.  If you have a 50amp RV you will need to 50 surge protector.

Al & Sharon
2006 Winnebago Journey 36G 
2020 Chevy Colorado Toad
San Antonio, TX

http://downtheroadaroundthebend.blogspot.com/

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7 minutes ago, Al F said:

There is little need to be exact to keep below 30amps.

Only use 2 high current devices. 

--  air conditioner plus microwave, or water heater, or toaster.

You can still run your TV, computers or such.

Or you could install a surge protector which will also monitor your total amps, display the amps on the remote and keep your RV safe with this:  https://www.amazon.com/Progressive-Industries-HW30C-Electrical-Protection/dp/B002UC6RSA/ref=sr_1_5/141-0908316-8726314?ie=UTF8&qid=1508965832&sr=8-5&keywords=progressive+rv+surge+protectors

I am assuming you have a 30amp RV since you have a 30' 5th wheel.  If you have a 50amp RV you will need to 50 surge protector.

I do have a 50 amp service and a 50 amp portable surge protector and was going outside to monitor the amps. I want to run 2 heater because the temps were going into the teens.  and I would keep checking the progressive surge for amp on what leg. that is when I decided I wanted those reading at the panel that is below the refrigerator to simplify things

2000 National RV Sea Breeze 5th wheel 30ft.

So.California

1950 F1 street rod

1949 F1 stock V8 flathead

1948 F6 350 chevy/rest stock, no dump bed shortened frame.

1953 chevy 3100 AD for 85 S10 frame

1968 Baha Bug with 2.2 ecotec motor 170 hp, king coil-overs,etc

1970 Baha Bug wihg 2332cc, King coil overs and everything else there is.

1998.5 Dodge 2500 4x4 Cummins, turbo, trans, injectors, lockers, bigger turbo,edge EZ upgrades for towing 35" BFG's, air dog lift pump etc.

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6 hours ago, Ed ke6bnl said:

BUT my question is can you put one induction coil around both L1 and L2 wires to get the total amp draw of the trailer. 

Good question Ed, I agree with Lou, here's my explanation. If you place a coil around one wire, it will of course, measure the amp flow in that wire but you already know that. HOWEVER if you circle it around TWO wires that are 180 out of phase with the other, since they cancel each other out, YOU WOULD ONLY BE MEASURING THE CURRENT FLOW DIFFERENCE I!!!! The meter would read ZERO if both legs were drawing the same current. If one drew 5 amps the other one 10, the meter would read 5 amps (difference).

In a 120/240 Volt Single Phase Three Wire Service typical of homes and many RV parks distribution scheme, if L1 & L2 each were supplying the SAME amps the Neutral current would be zero. It is good practice to balance the L1 & L2 loads to avoid unnecessary I Squared R wasted heat losses in the Neutral conductor. That was always the goal in our shop.

The main circuit breaker in the RV's panel will only allow x amps (30 or 50) to flow downstream of and after it so you cant draw more then that for long before tripping. The overcurrent protection device (usually a circuit breaker) in the RV Parks pedestal will similarly only allows X amps of current flow which the devices and wire downstream and after is capable of passing without damage.

A coil around each wire/leg in a 120/240 volt Single Phase Three Wire system sounds like what you need.   

DISCLAIMER I'm a longgggggggggg retired EE and rusty on this so NO WARRANTY but I think it still holds true.

 

John T

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4 hours ago, Ed ke6bnl said:

I do have a 50 amp service and a 50 amp portable surge protector and was going outside to monitor the amps. I want to run 2 heater because the temps were going into the teens.  and I would keep checking the progressive surge for amp on what leg. that is when I decided I wanted those reading at the panel that is below the refrigerator to simplify things

We have often run 2 heaters, one front, one back, when on 30 amps.   First, both are on low, so drawing about 7.5 amps on the 15 amp circuit.  Second.  THEY ARE ON DIFFERENT CIRCUITS.   In fact, we use one in the bedroom which goes through the inverter, and the second in the living area on a circuit THAT DOES NOT GO THROUGH THE INVERTER.  

2 heaters the biggest concern should be total amps pulled, and what circuits are they on and what else is on that circuit.    Isn't your furnace working?

Barb & Dave O'Keeffe
2002 Alpine 36 MDDS (Figment II), 2018 Ford C-Max HYBRID
Blog: http://www.barbanddave.net
SPK# 90761 FMCA #F337834

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Well the two Amp meters are coming by the slow mail from china and when they come I look forward to mounting them. I do appreciate all the knowledgeable people that answered my question.

2000 National RV Sea Breeze 5th wheel 30ft.

So.California

1950 F1 street rod

1949 F1 stock V8 flathead

1948 F6 350 chevy/rest stock, no dump bed shortened frame.

1953 chevy 3100 AD for 85 S10 frame

1968 Baha Bug with 2.2 ecotec motor 170 hp, king coil-overs,etc

1970 Baha Bug wihg 2332cc, King coil overs and everything else there is.

1998.5 Dodge 2500 4x4 Cummins, turbo, trans, injectors, lockers, bigger turbo,edge EZ upgrades for towing 35" BFG's, air dog lift pump etc.

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2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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10 hours ago, Ed ke6bnl said:

Well the two Amp meters are coming by the slow mail from china and when they come I look forward to mounting them. I do appreciate all the knowledgeable people that answered my question.

Ed, I have ordered several Flea Bay items from China, some came quick others Oh Well lol so you may be surprised. I have been pleased with many of their low priced electronic gadgets other then at times the instruction were only in Chinese grrrrrrrrrrrrrr  but even if in  English they weren't the best I've ever seen.

Best wishes and God Bless, thank for the update

John T  Live from Cracker Barrel Parking Lot in Hot Springs Arkansas

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8 hours ago, Mntom said:

Be careful there, John. The last time I was in Hot Springs it wound up costing me about $13,000 in one day. I broke my truck and wife broke her wrist!

Thanks for the warning, were back at the campground all done at Hot Springs, so far its only cost me a glass water jug, two Ride the Duck tickets, two bottles of wine and a Senior $15 campsite fee. Last night we ate at Cracker Barrel and stayed overnight in their parking lot, headed for Marshall Texas then SKP headquarters in Livingston then Austin. If I get further north in Texas I may get to visit Kirk. 

John T

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