Wiring loom opposing currents

Submitted: Saturday, Jan 09, 2010 at 15:53
ThreadID: 75032 Views:2427 Replies:6 FollowUps:9
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Hi All,

Have a quick question about whether it is wise to put opposing currents in the same loom.

Example. I am looking at running my solar panel in the same loom as my compressor, fridge and other accesories I have attached to the back of the truck?

I suppose is what I am asking is current will be going one way creating magnetic force and current will be going the other way also creating magnetic force. I can only presume if it was AC then there would be no probs but because it is DC then there might be?

I hope I have explained my question well enough and somebody can answer me.

Peter
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Reply By: dbish - Saturday, Jan 09, 2010 at 16:07

Saturday, Jan 09, 2010 at 16:07
Hi Peter its AC currents that are induced into other wires not DC should be no problem at all. Daryl
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Reply By: Member - Allan B (QLD) - Saturday, Jan 09, 2010 at 16:14

Saturday, Jan 09, 2010 at 16:14
No problem at all Peter.

Cheers
Allan

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Reply By: Bonz (Vic) - Saturday, Jan 09, 2010 at 16:35

Saturday, Jan 09, 2010 at 16:35
You're only issue would be the amount of current that you'll be running. If it is in close proximity to another cable and they are at or near capacity you'll lose efficiency with the combined heat and that may cause problems, but nothing related to the electric fields,
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Follow Up By: Member - Fred B (NT) - Saturday, Jan 09, 2010 at 17:25

Saturday, Jan 09, 2010 at 17:25
Not if you run the correct cable sizes....
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Follow Up By: Bonz (Vic) - Saturday, Jan 09, 2010 at 17:29

Saturday, Jan 09, 2010 at 17:29
hahahaha Fred I didnt mention cable sizes, but at or near their rated capacity, I would be concerned. I always overrate cable sizes and run them well under capacity. You're spot on there.
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Follow Up By: olcoolone - Saturday, Jan 09, 2010 at 18:49

Saturday, Jan 09, 2010 at 18:49
Cable ratings are always less if run in a multi cable loom, this has nothing to do with the cable being the right size.

Rule of thumb is between 5 to 10% capacity per cable is lost.
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Follow Up By: Member - Fred B (NT) - Saturday, Jan 09, 2010 at 19:02

Saturday, Jan 09, 2010 at 19:02
that is corect... that is why you need to run the "correct' size for the situation at hand.... Something which most auto manufactures do not comprehend... they run the smallest cable size possible based on intermittent use theory... lol.
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Reply By: Member - Mike DID - Saturday, Jan 09, 2010 at 19:00

Saturday, Jan 09, 2010 at 19:00
Why do you think this could be a problem ?

Have you seen the size of the wiring looms in modern cars with more than 50 wires in one bundle ?

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Follow Up By: Member - extfilm (NSW) - Saturday, Jan 09, 2010 at 19:18

Saturday, Jan 09, 2010 at 19:18
Hi Mike,

This is why I am asking because if you think of water...... water flows in one direction..... All those 50 wires in one bundle, the current is flowing in one direction.......

Have you ever magnatised a screw driver by wrapping a wire round and round and round?

This is what I am asking........ will there be a problem with having current going from the solar panel in a south north direction in the loom and having power traveling in a north south direction. Hence Opposing force.

I have laid elec conduits in my time and one of the requirements of energy aus is to have the conduits 100mm apart because of the current traveling through......

I am just not sure this is why I am asking the question

Peter
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Follow Up By: dbish - Saturday, Jan 09, 2010 at 19:55

Saturday, Jan 09, 2010 at 19:55
Peter thats whyI posted its only a problem with AC not DC how many diferent answers do you want?
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Follow Up By: Member - extfilm (NSW) - Saturday, Jan 09, 2010 at 20:07

Saturday, Jan 09, 2010 at 20:07
No worries..... Thanks mate...... I only asked because on most vehicles the alternater has a seperate cable straight to the battery but I took it on board hours ago and have since got it wired.......

I was only explaining to mike as to why I asked in the first place.

Just don't want to destroy a 70k ute.

Thanks again dbish..... Lets hope the battery will last more than a week with fridge cranking ;)
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Reply By: Richard Kovac - Saturday, Jan 09, 2010 at 21:48

Saturday, Jan 09, 2010 at 21:48
Peter

The consensus today is that the electron do not flow at all the just rub against each other transmitting the energy a long the line - to +.

The magnetic forces you would get would be at there greatest when the wire is coiled (as in a solenoid) running straight they should be OK. just think about the cars charging system when not running the current flow would be in one direction and when charging it would be in the other. so if it works for them it should work for you..

Cheers

Richard
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Follow Up By: GlennD - Sunday, Jan 10, 2010 at 17:37

Sunday, Jan 10, 2010 at 17:37
I must be way off track , I thought the elctrons stayed still but the 'holes' between them moved , + to -.

LOL,

Glenn.
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Follow Up By: Richard Kovac - Sunday, Jan 10, 2010 at 18:16

Sunday, Jan 10, 2010 at 18:16
You maybe right Glenn who nose.. :-) but they will still travel - to +...

Cheers

Richard
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Reply By: Member - Mike DID - Sunday, Jan 10, 2010 at 17:55

Sunday, Jan 10, 2010 at 17:55
- "I have laid elec conduits in my time and one of the requirements of energy aus is to have the conduits 100mm apart because of the current traveling through...... "

The reason I asked why you raised this question, is because no-one has raised this as a possible issue in recent years. I was curious as to your background that would make this a possible issue.

Electrical conduits need to be separated because they could carry high currents - especailly fault currents in the thousands of amps - that could cause currents to be induced in other cables that are running parallel to them for very long runs.

The only vehicle wiring that carries really high currents is the starter motor, but there aren't any cables that run prallel and close to it.

Even though the current is DC, high currents can be induced in nearby wires whenever the Starter current starts or stops. The magnetic field changes dramatically when 300 amps is switched on or off. Because of the fast rise time, this will induce more current in other wires, than 300 amps of AC at 50 Hz.

In modern cars there are many circuits that carry AC rather than DC. Solenoids e.g. for EGR, can be pulse-width modulated with a 12 volt square wave so they can be progressivel opened with the CPU needing to put out a varying analogue voltage. Again this 12 volt square wave can induce a higher current than 12 volts of AC at 50Hz.
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