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Discuss Need help with earthing DC supplies in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

M

minimax1988

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I have an issue where i need to earth a high powered supply from a 12VDC car battery to a control cabinet. I was wondering is it safe to run a grounding cable from an engine frame to the supply cabinet without causing any hazards or accidents?

Can anyone help me to answer this?
 
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M

montybaber

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  • #2
Is this control cabinet in a van etc? what is it controlling?
 
S

sparkyork

it sounds like it might be in a car doesnt it (engine frame??)

cars and vans use a negative earth setup, so the feed goes to the cabinet thing from "+" on the battery (via a fuse), and the neutral (or commonly called earth in automotive setups) ends up going back to the "-" terminal on the battery, usually via a metalic part of the chassis. its not normal to attach straight on to the negative on the battery.

to earth the cabinet? trying to think about this logically....if you connect cabinet to car chassis then that connection ends up going back to the "-" on the battery, as well as the main power for whatever your running, not hundred percent sure but if yuou connect it like this then your making the cabinet part of the electrical system, if for some reaon something happens (i.e a 12v feed comes in contact with the cabinet) then this 12v feed should effectively blow its protective device as this would be a dead short?

what sort of problems are you thinking you may be getting? is this some kind of audio setup mounted in a cabinet?

bit more info and might be able to help further.

rich
 
M

montybaber

  • Thread Starter Thread Starter
  • #4
all components in a car/van are wired using a fused positive feed and the negative is wired to the chasis earth so all connections are in parrallel
 
S

sparkyork

what do you reckon then monty? like your post better than mine says the same thing sept ive got an essay!!

to be honest id be dubios about trying to creat an earth from the cabinet cos its not really an earth is it, how about an earth rod!!

rich
 
S

Shakey

  • Thread Starter Thread Starter
  • #6
all components in a car/van are wired using a fused positive feed and the negative is wired to the chasis earth so all connections are in parrallel
correct Monty, they are

now when i started out i worked on positive earth vehicles, and 'insulated return' petrol tankers etc, they even had earth leakage detection on them, great fun for fault finding!

To the original post, are you talking about extending a vehicles 12/24V supply out to an external load? And are you talking about extending the vehicles uninsulated chassis return system to a further uninsulated metallic return path, or insulated return and 'earthing' for safety purposes?

Again, more info would be good!
 
M

montybaber

  • Thread Starter Thread Starter
  • #7
what do you reckon then monty? like your post better than mine says the same thing sept ive got an essay!!

to be honest id be dubios about trying to creat an earth from the cabinet cos its not really an earth is it, how about an earth rod!!

rich
sorry lol :) im a bit thick, you will have to excuse me!
 
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