Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wiring Question

  1. Sep 11, 2010 #1
    Hey guys, i have a few basic soldering and wire connecting questions and would like you guys' help since I am not familiar with wiring.

    Basically I have 2 wires that I want to tap into the "add-a-circuit" pictured below. What kind of connector is the one in blue? If I want to tap 2 wires into it, what would be the ideal way to do so and would it be a reliable connection?
    Add-A-Circuit.jpg


    Thanks in advance!!!
     
  2. jcsd
  3. Sep 11, 2010 #2

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    This looks like a way to add a fused circuit to an existing auto fuse block. One of the fuses is for the existing circuit and the other fuse protects the circuit attached to the red wire. The blue connector is a crimp-on type. The red wire has been crimped in one end and you supply the wire for the other end and use a crimping tool to make the connection.
    crimp-contacts-using-crimp-tool-200X200.jpg
     
  4. Sep 11, 2010 #3

    Averagesupernova

    User Avatar
    Gold Member

    If you want to tap 2 wires in and have them both protected by a fuse just connect those 2 wires to the one shown in your picture. The 2 wires together can draw no more current than what the fuse is. You have to determine if this will cause nuisance fuse blowing, etc. Also, do not size the fuse for more than either wire can safely carry. I'm not a big fan of this type of add on. I suppose it depends on how much current the extra wire will carry.
     
  5. Sep 11, 2010 #4
    Yep you got it. So if I wanted to connect 2 wires (as shown in the diagram i drew on the bottom) into the blue crimp-on connector, all i have to do is feed it all the way in there and the crimp it? If so, I have 2 question:

    1.) How will i know if the 2 wires have a strong connection with the wire inside the blue crimp-on connector?
    2.) Do i make a mechanical connection between the 2 wires first by twisting it into a single strand before putting it inside the blue crimp-on connector?

    [PLAIN]http://img210.imageshack.us/img210/2489/crimp.jpg [Broken]


    It's for a fusebox inside the car. The wires I'm about to connect draw very little current so I should be good. When you said not to size the fuse for more than either wire can carry, do you mean that if both the wires draw 5amp, i should use a 5amp fuse instead of a 10amp?
     
    Last edited by a moderator: May 4, 2017
  6. Sep 11, 2010 #5

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    Normally this type of crimp-on is intended for only one wire for is gauge range. But you might be able to use two smaller gauges.
    It would be best to keep the stripped ends of the wire parallel to each other, then insert and crimp.
    What Averagesupernova meant was that the fuse size shouldn't be more than the amp-capacity of the wire (how many amps it can carry without getting too hot). i.e. the wire would burn up before the fuse blows.
     
  7. Sep 11, 2010 #6
    I'm doing this for a car, and the fuse I pulled out of the car is 10amp. I replaced that fuse slot with the "add a circuit" and placed the 10amp fuse onto the "add a circuit."

    The wire I'm trying to connect it to is 24 awg.

    Would that be a problem?


    -------------------------------------------------------------------------
    I did some researching on how much current 24 awg wires can carry but I wasn't sure if I was researching the right material so I didn't post them on here to prevent from confusing you guys with my lack of understanding.
     
  8. Sep 11, 2010 #7

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    This http://www.powerstream.com/Wire_Size.htm" [Broken] indicates 24AWG copper wire is good for 3.5 amps. What load are you planning on for this circuit? It needs to be less than this. And your fuse would be too large for the wire. You would need 20AWG wire for a 10amp load.
     
    Last edited by a moderator: May 4, 2017
  9. Sep 12, 2010 #8
    Yeah that was the website I was on :)

    Well dlgoff, I'll explain what my overall intention for doing this wiring.

    Basically I bought an oil temperature gauge for my car so it can gauge how hot the oil is. The gauge came with a wire harness that has 4 strands of 24 awg wires. I plug the harness into the gauge, and I connect it into the "add a circuit" blue crimp-on connector.

    Then, the "add-a-circuit" gets plugged into one of the fuses in the fuse box in the car. Since I want the gauge to power on whenever I turn the car ignition to "ON", I find the fuse in the car that supplies power when the ignition is turned to "ON." That particular fuse is 10a. I then replace it with the "add-a-circuit" and place the ignition "ON" fuse onto the "add-a-circuit".

    The reason I used an "add-a-circuit" was so that I didn't have to solder the gauge wire into any wires in the car incase I want to remove the gauge in the future.

    -------------------------------------------------------------------------------------
    To answer your question, I honestly don't know what load I'm planning on for this circuit... The gauge draws about 1 ma.

    The gauge came with 24 awg wires so there's not much I can do...
     
    Last edited by a moderator: May 4, 2017
  10. Sep 12, 2010 #9

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    Okay. The picture in the OP shows two fuses. It looks like the fuse connecting the red wire is on the top. This one should be for no more than 3.5 amps. Since your gauges power wire is 24AWG then you should be okay with a 3 amp fuse. The bottom fuse, if I'm correct, should be the 10 amp fuse; to supply what ever it was intended for originally.

    So if you are just wanting to add one circuit, then all you need is to crimp the wire from the gauges into the connector. Or have I missed something?
     
  11. Sep 12, 2010 #10

    Averagesupernova

    User Avatar
    Gold Member

    Just curious, what type/brand gauge did you buy? Can you provide a link?
     
  12. Sep 12, 2010 #11
    No you got it 100%, and THANK YOU SOOOOOO MUCH for clearing this up for me. So I guess the fuse I should use depends on the size of the wire and not how much power the gauge actually draws? That makes sense.

    And you're right, all I have to do is crimp the wire into the add-a-circuit. But you mentioned that this type of crimp connector is generally intended for only one wire.

    If I wanted to connect two 24 awg wires into the blue crimp-on connector (and I have to since I have two gauges that have to go into the same fuse in the car), did you mean to keep the wires parallel without twisting it into a single strand, meaning just insert the two wires straight into the crimp-on connector and crimp?
     
  13. Sep 12, 2010 #12
    Hey! The brand of the gauges is called "Prosport Gauges." Here's their website: http://prosportgauges.com/

    I bought the "Performance Series" 52mm electrical water and oil temperature gauges.
     
  14. Sep 12, 2010 #13

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    Yes

    Looking at these, it appears that they are mechanical movements with the power being used for the lighting. If this is the case, I don't see any problem with putting both circuits together. i.e. Not much current is needed to light them. Just make sure that the crimp is good.
     
  15. Sep 13, 2010 #14
    Thanks.

    And about the add-a-circuit, the blue crimp-on connector only supports 18-16 AWG but my wire is 24 AWG. Someone suggested twisting my 2 wires together and double crimping the connector.

    What do you think? Or is there a better solution?


    Edit: What do you think if I bought 18 awg wires and solder it to the 24 awg wire?
     
    Last edited: Sep 13, 2010
  16. Sep 13, 2010 #15

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    It would be close, but I think you could get away with crimping both 24AWG wires together. I got to looking at the wire chart and it say 24 gauge wire has a 0.02" diameter and 18 gauge has a 0.04" diameter. So maybe you are right about twisting the stripped ends together in order to take up a little more cross-sectional area.

    Soldering them to an 18 gauge wire to be crimped will work too.
     
  17. Sep 15, 2010 #16
    If I use the 24 ga to 18 ga approach, can I still use 3.5 amp fuse (i only have 3.5a and no 3a fuse) for the 2nd slot of the "add-a-circuit"?

    Also, if I splice 2 wires (24 awg) to the add-a-circuit, would I need a 7 amp fuse since a single 24 awg wire's maximum amps is 3.5a and i'm connecting 2 wires? And if i had 3 wires, it'd be 10.5a (3.5x3) and so on...? Or would i just use a single 3.5a fuse regardless of how many 24 awg wires i'm connecting?
     
    Last edited: Sep 15, 2010
  18. Sep 15, 2010 #17

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    Yes since the weakest link is the 24 awg wire.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Wiring Question
  1. Home wiring question (Replies: 2)

  2. Wiring Question (Replies: 1)

Loading...