I'm relocating a battery in my son's Impreza (from the front to the back). I have to run the positive battery cable from the rear up to the front in order to power the electrics which need to be powered. To run the new cable, I want to use line clamps to provide support for the cable and so it will not rub on the frame and create a short circuit. For reference, here's what a line clamp looks like:

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I want to ensure I'm doing it correctly, so my question is, How do you properly size the line clamp to what you are trying to support? In my case, the cable I'm running has a width of ~.41". I selected 1/2" clamps. What I'm worried about is whether the extra space left in the clamps will allow for wiggle room and cause abrasion to the cable. Should I have picked a smaller size which would stretch the clamp around the cable and hold it more firmly or would have that been a mistake? Is there a rule of thumb for selecting these regardless of the size of what is being supported?

  • You could use heatshrink tube, duct tape or some rubber from the inner tube of a bicycle tire to fill the gap...
    – Hobbes
    Jan 26, 2017 at 14:28
  • @Hobbes - I'll keep it in mind, depending on how much space there actually is to soak up. It may just be it'll work peachie. Jan 26, 2017 at 14:31
  • I'd add a fuse near the battery in case that 20 ft power line gets damaged at some point. It might save a fire.
    – cory
    Jan 26, 2017 at 14:59
  • 2
    @cory - Not my car ... can go up in smoke for all I care ... I guess I'll ensure the door handles work, though :o) Good idea, though, really. I also bought some grommets to put into place I can run the cable through the body with. I still have to mount the battery in the trunk ... not exactly sure how I want to accomplish that. Probably just find a battery box which will work for it. Jan 26, 2017 at 15:04

1 Answer 1


If your goal is to hold the cable in place and to avoid chaffing, then you need a clamp that will grasp the cable. They make the same clamps you've pictured in 3/8" which would be a little snug, but wouldn't allow movement. The larger cables have more insulation (typically), so the snug fit should not damage it.

These work great. I have used these in aircraft applications, as well as automotive.

An alternate would be a nylon clamp which would not react if chafed through the insulation.

enter image description here

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