How can I safely and properly mount this resistor?

[FastKat]

I am finishing off an under-hood wiring harness on my Jag hotrod and I need to run a carbon film resistor "inline" on one of the wires inside the harness loom. In other words, I have to splice in a carbon film resistor in one of my wires under the hood of my hotrod. (picture of carbon film resistor below)

The catch is, I don't want to just solder it in and put some heat shrink tubing over it. I think I should make something a little more durable.

My best idea so far is to solder the resistor onto the wires, cover the resistor and the wires with hot glue, and then slide a piece of heat-shrink tubing over the glue-covered resistor and shrink it down. My concern is that 1) the hot glue might get soft when the under-hood temperatures start to go up, and 2) when I hit the heat-shrink tubing with a heat gun to shrink it, all of the glue is going to run out.

Any suggestions?

 

[Heavy Metal Doctor]

I deal with diodes in electrical systems that are installed in trucks / machinery which are installed pretty much just the way you are describing -- no hot glue, just good quality heat-shrink tubing and then wrap the wirng with split loom. It's fine as long as the heat you are talking about is not a spot like 2 inches away from the exhaust manifold or something extreme like that.

 

[Steve from Socal]

Hot melt will get soft at under hood temps; if you want to encase the resistor in a potting compound perhaps JB Weld? I really don't see why a soldered connection with shrink would be an issue. There are plug and socket designs that you could use sort of like an inline fuse holder.

Steve

 

[CraigFL]

The way I would do it is to use a terminal block. This doesn't allow the resistor to be stressed by pulling on the wires. The block can be mounted to the body and the resistor to the terminal strip securely.

 

[bgoodwin]

I work with outdoor construction equipment. When we need to make this type of connection I use a polyolefin heatshrink tubing that is lined with a thermoplastic adhesive. The adhesive melts when you shrink the tubing to give a completely weather proof seal. This type on shrink tubing should be available at most auto parts stores and is good to 260 degrees continuous temps.

 

[FastKat]

Thanks for the info guys. I do have some medium-wall adhesive lined polyolefin heat shrink tubing left. Most of the stuff I have used up to this point has been the thin-wall stuff, which is actually much more flexible. I will do a test with just the heat shrink tubing and see how it looks/feels.

I work with outdoor construction equipment. When we need to make this type of connection I use a polyolefin heatshrink tubing that is lined with a thermoplastic adhesive. The adhesive melts when you shrink the tubing to give a completely weather proof seal. This type on shrink tubing should be available at most auto parts stores and is good to 260 degrees continuous temps.

 

[jabberwoki]

I am finishing off an under-hood wiring harness on my Jag hotrod and I need to run a carbon film resistor "inline" on one of the wires inside the harness loom. In other words, I have to splice in a carbon film resistor in one of my wires under the hood of my hotrod. (picture of carbon film resistor below)

The catch is, I don't want to just solder it in and put some heat shrink tubing over it. I think I should make something a little more durable.

My best idea so far is to solder the resistor onto the wires, cover the resistor and the wires with hot glue, and then slide a piece of heat-shrink tubing over the glue-covered resistor and shrink it down. My concern is that 1) the hot glue might get soft when the under-hood temperatures start to go up, and 2) when I hit the heat-shrink tubing with a heat gun to shrink it, all of the glue is going to run out.

Any suggestions?

I would like to see your jag hot rod?

 

[FastKat]

I would like to see your jag hot rod?

Here is a link to my Jag's webpage:

http://www.buyrcars.com/jag.htm

It's still a work in progress, though there is now a light at the end of the tunnel. I am going to try to get the wiring and cooler lines on the transmission this weekend so it will finally move on it's own power... for the first time in the 6 or so years I've owned it!

 

[Steve from Socal]

You are doing a very nice job on your Jag. Everybody should have an "Uncle Buck" he seems like he saved the day many times over!

Steve

 

[FastKat]

Yea, Uncle Buck is definitely a big help. We worked together on parts of the project where we just didn't have a clear idea of what the solution would be.

You are doing a very nice job on your Jag. Everybody should have an "Uncle Buck" he seems like he saved the day many times over!

Steve

 

[Boiler]

Use a 2 circuit terminal strip like the 3 circuit one at the top left of this page;

http://www.mcmaster.com/#terminal-strips/=8zi9ec

put the wires both on one side, each opposite of one end of the diode or resistor. This allows you ease of test, replacement, visual confirmation, etc.

They also have insulated strips as well. You could use a din rail mounted terminal block (google wago) as well. They slip right into the wire holes.

 

[RM209]

FastKat: Well done! I'm particularly impressed with the wiring job, and how you integrated LS engine wiring into a 25 year old British car.

RM209

 

[FastKat]

Thanks! It took a lot of research but it's coming along nicely. Slowly, but nicely.

BTW, I mounted the resistor in a piece of medium-wall adhesive-lined heat shrink tubing. It seemed rigid and durable enough, and I am happy with the way it turned out. I would have used a terminal block or a piece of silicon board or something, but I am trying to hide as much as I can so I get a clean-looking install.

FastKat: Well done! I'm particularly impressed with the wiring job, and how you integrated LS engine wiring into a 25 year old British car.

RM209

 

[Torque1st]

When you embed resistors and other components in wiring harnesses derate them by a factor of 4 to avoid overheating them. The normal wattage or amperage ratings are based on free air in a consumer type electronic device with normal ambient temperatures.

 

[FastKat]

Can you explain that a little more please? Should I get a higher resistance (ex: take the desired 470 ohms x 4) or should I get a higher wattage (use a 2 watt resistor instead of a 1/2 watt resistor?)

When you embed resistors and other components in wiring harnesses derate them by a factor of 4 to avoid overheating them. The normal wattage or amperage ratings are based on free air in a consumer type electronic device with normal ambient temperatures.

 

[Torque1st]

Use a 2 watt resistor instead of a 1/2 watt resistor.

You need to figure the power dissipation your application requires. If you only require 1/8 watt then the 1/2 watt resistor would be OK.