Sizing wire for a TruckFridge

[GreyDawg]

Hi --

I've ordered a portable Truckfridge -- TB41 -- which will plug into a 12V socket. The wire for the socket will run 5.5 feet up the passenger wall, 6 feet across the ceiling, and 5.5 feet down the driver's wall to the 12V fuse block. That's 17 feet, or 34 feet doubled.

The Truckfridge guy said that the label on the fridge says it pulls 3.x amps (I can't find my scribbled notes right now). Using the Blue Sea circuit wizard, and plugging in 4 amps and 34 feet, the suggested wire is 14AWG.

HOWEVER, I've also read on some forum or another that a fridge compressor will spike higher than the stated amp pull when it kicks in, and that you should wire and fuse for that.

Is that correct? And if so, how many amps should one allow? If, for example, I put in 7 amps and 34 feet, the BSCW comes back with 10AWG, and I assume I'd use a 10 amp fuse.

How do I figure out the right gauge wire for the fridge?

Thanks.

[Bbasso]

Personally I'd use 10 awg and a 10 amp fuse... but I would wire directly into the fuse block.

(I did that for my Engel, just much shorter distance)

[GreyDawg]

Right ... so what I read about a "spike" (which I guessed -- SWAG -- at 7amps) when the compressor turns on is correct?

[Bbasso]

I know there is a spike but I don't know how much, but 10 gauge should cover it with ease also a 10 amp fuse.

[86Scotty]

I would go with 12 or 14 gauge and a 15 or 20 amp fuse. 10 gauge wire supports 30 amp fuse but that's overkill IMO. When you have this wire in your hand you will see that it is gigantic for such a task. Compare it with the cord that comes with the fridge, which is 12 or 14. Your TF will have it's own fuse so don't worry about having a bigger fuse to the outlet. TF fuse is 15 or 20 amps I'm pretty sure. It is right on the panel by the plug in, easy to replace should you ever need to. It is not an internal fuse.

Why would you need to double it, for the ground? That's a huge waste of wire. Just ground the outlet right next to it with a self tapping screw and a ring terminal. Your whole van body is a ground. Ground should be close to the appliance.

[GreyDawg]

Thanks, all.

Well, the question is interesting but moot.

The TB41 has a 41 liter capacity.... or perhaps a 39 liter "gross capacity" per the IndelWebasto website.

Truckfridge says the capacity is 1.5 cubic feet., which is 42 liters.

Imagine my annoyance when I opened the TB and saw the very small capacity. I threw a tape on it: 2,075 cubic inches, or 33 liters, or 35 quarts , or 1.16 cu ft.

1.16 cu feet is only 77% of the advertised 1.5 cu ft. This thing is much smaller than advertised.

I'll call TruckFridge tomorrow about returning it. Guess I'll be driving from Texas to New Jersey next week via Kentucky....

Looks like another season with ice; I'll figure out a new plan for next year.

[arctictraveller]

Wow, sorry it turned out that way. As for the surge current, it's such a short amount of time (a second or two) that it's a non factor in sizing the fuse. Fuses are not instantanous, they take time to open. The higher the overload, the quicker they blow, but even a fast acting class T fuse takes a bit of time before opening.

[86Scotty]

Sorry to hear it Greydawg. I figured you did your homework but I was thinking that was awful small for full timing. My front door TF 130 is barely big enough for me but I stock it like a home fridge because, essentially, it's my home during the week nowadays. The big steel TF 70 liter I have is about the only way I could do a chest fridge for full timing. It's a rebranded IndelB TB74.

Travel Box & Cruise TB74 Steel - IndelB

[boywonder]

FWIW...I wired my TF49 with 12ga and it's a fairly long loop......been working great for a few years....and according to my battery monitor it pulls around 3 amps.

I think all of the Truckfridge sizes have the same compressor so same amps. The larger units will just run longer to keep things cold.

[hogasm]

Per Truckfridge website
Wire gauge sizes - Maximum length of cables in feet of stranded copper. DO NOT USE SOLID COPPER WIRE!
12 V
8 feet – 12 gauge AWG
12 feet – 10 gauge AWG
3.) Any switches must have a breaking load not less than 15 Amp (10 A if powered at 24 Volt).
4.) Make sure the polarity is right: connect the red cable to the positive terminal (+) and the black cable to the
negative terminal (-). NOTE: Even if the polarity is incorrect, the light may come on inside the fridge, but the
compressor and fan will not run. This will not damage the fridge if corrected promptly. Merely correct the
polarity and the fridge should run properly.
Attention! Never connect bare electric wires, and use only connectors of a size suitable to the gauge of the wire
being used.
5.) Protect the supply line with a maximum 15 A fuse. – Remember - fuses protect against wire overheating!