4 guage wire through firewall?

Question

i plan on drilling a hole, but i'm not sure what size it should be.

any ideas?

Answer 1

Drill the hole large enough so that the grommet will fit.

You were going to use a grommet weren't you?

Use a grommet large enough to fit the 4ga wire you will be using. This will protect the wire from being cut at the firewall from rubbing on the metal. If you don't use one (plastic or rubber) you could easily have a short, and the potential for a fire.

So, you need to drill a hole large enough for your grommet, and they vary in size and design...

Answer 2

just measure the wire with a ruler or put it next to some drill bits and see which bit is bigger than it.   or just to be safe drill a 1" hole then you can try putting a grommet in so the wire isnt resting on bare, sharp metal, or use electrical tape and put it around the edges of the metal.

Answer 3

If you are using the standard wire gauge sizing method, you will need a 15/64" diameter hole.  That is closest to a 1/4" drill bit.  You may have to go bigger if you have thickly insulated wire.  I would go with a larger 5/16" or even a 3/8" bit and caulk the hole around the wire with high temp silicone to avoid the wire sheathing rubbing off on the fire wall and causing a short.  Doing this will also help with possible water and air infiltration.  In addition, you may want to try to find some way to provide strain relief on both sides in case the wire gets pulled by something.  It could be as simple as tying a knot on both sides of the hole if the wire is stranded.   If the wire is solid, Radio Shack used to sell strain reliefs that clamp on.  I don't know if they still do.  Good luck!