connect multiple items at +12v in fusebox
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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=107921
Printed Date: May 03, 2024 at 2:11 PM
Topic: connect multiple items at +12v in fusebox
Posted By: anewman
Subject: connect multiple items at +12v in fusebox
Date Posted: October 04, 2008 at 2:55 PM
To tidy things up I am planning to use a fuse holder rated up to 30a with a 30a fuse, connected to the positive wire at the fusebox and to have this connected up to a double bullet connector, and then to have that connected to a number of devices and another double bullet connector. Items connected will include 20a, 15a, 5a, 5a.
I am just wondering if this is a good idea, or if there's a better way? Thanks in advance.
Replies:
Posted By: i am an idiot
Date Posted: October 04, 2008 at 5:34 PM
An automobile manufacturer will not spend any extra money on wire. The wire supplying the fusebox is probably not large enough to handle an extra 30 amps of current. If you are wanting to have these items only hot when the key is in accessory or ignition position, You really need to run a 10 Ga wire to the battery with a fuse and fuse holder mounted at the battery, connect it to terminal 30 of a Bosch/Now Tyco automotive relay. Connect your new devices to terminal 87. Ground terminal 85 and connect 86 to a switched or accessory wire from the vehicle. If we knew what kind of car you had, we could even give you a wire color and location to find the wire.
Posted By: anewman
Date Posted: October 04, 2008 at 6:30 PM
The higher current ones (20a and 15a) are only used momentarily (central locking and parking light flasher input), and generally only used when the rest of the electrics are off. Don't know if that makes it acceptable to just connect up to the fusebox?
Should the battery -> fusebox feed wire ever get warm in normal use? I have noticed mine get quite warm - although doesn't appear to get warm enough to cause any kind of damage.
Car is Skoda Favorit but I have access to wiring diagrams so am able to determine location and colour of wires etc :)
Posted By: anewman
Date Posted: October 05, 2008 at 9:12 AM
This is what I had in mind with one device connected and 4 female receptacles for other devices.
Posted By: i am an idiot
Date Posted: October 05, 2008 at 11:17 AM
If the devices require constant voltage, You can run to battery without the relay. I had assumed you needed switched power since you wanted to go to the fuse box.
Posted By: 04nata
Date Posted: October 05, 2008 at 12:17 PM
I just ran a 10 gage wire direct to the battery, with a 15 amp fuse, then ran it back and spliced in toggles that lead to the different items, headrest monitors, dvd, cathode lights, etc.
Posted By: anewman
Date Posted: October 05, 2008 at 12:40 PM
If I remember correctly there is a way of passing an extra cable through the bulkhead without drilling, just means stripping everything down. Seems likely to be safer at battery. Fusebox is the lazy option as it is in the passenger compartment 
Posted By: i am an idiot
Date Posted: October 05, 2008 at 12:48 PM
If we knew what kind of a vehicle you had, we could probably tell you where you can run a wire through the firewall.
Posted By: anewman
Date Posted: October 05, 2008 at 1:14 PM
As mentioned above, Skoda Favorit. The newer Skoda Felicia has the same chassis - guessing neither were exported to the US though. I know I can definitely send a wire through the back of the instrument panel where the hydraulic headlight adjusters pass through, as the rubber grommet there has "nobbles" on that could be chopped off. Would be better passenger side though. I think with some exploring I'll find somewhere.
Posted By: i am an idiot
Date Posted: October 05, 2008 at 1:36 PM
Sorry, I did read that earlier, but they do not sell those here. I sent Howie a PM, he should be able to help you with a location.
Posted By: 04nata
Date Posted: October 05, 2008 at 1:42 PM
If you have any kind of stereo system with an amp you should have already have some 8 gauge or bigger going thru thru firewall, just go thru there,,,,if not, then there is no better time than the present to get that right angle drill out and put a nice 1/2"-3/4" hole in there, for this wire and any future wire you may need.................drill it, drill it, drill it, be sure to use some loom over the wire in the engine compartment
Posted By: i am an idiot
Date Posted: October 05, 2008 at 2:47 PM
OK It's either a a Golf or A3 basically or a Polo, if you can't see any grometts, 1) Look at firewall behind engine block, 1) If it's an auto there might be a gromett where the clutch cable would have gone through or behind the ABS box, as a last resort look up where the wiper gear is located, there might be a way in through the to the internal fusebox. The gGolf has a big nasty to get at gromett where main loom goes through but it hass niples you can cut off and get through. This is assuming it's a current shape
Posted By: anewman
Date Posted: October 06, 2008 at 8:17 AM
Thanks for the pointers so far guys. I have had a good look at how I might get a wire through the firewall, including underneath and this is what I have come up with...
I think I have three options. Try force the wire through the big hole in the existing rubber grommet. Make an additional hole in the big rubber grommet. Or drill a new hole via the hole on the left. I believe there is enough clearance behind there, the only thing is there is sound proofing material behind it.
Would be much easier on the driver's side though :)
Posted By: i am an idiot
Date Posted: October 07, 2008 at 9:06 AM
Bottom picture left hand grommet. See the nipple on the right side of said grommet? Cut it off and run wire through hole. That is why they are there.
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