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/cgi-bin/YaBB.pl General Category >> The Cafe >> Vacuum line is not a good insulator!!!! /cgi-bin/YaBB.pl?num=1739966573 Message started by Dave on 02/19/25 at 04:02:53 |
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Title: Vacuum line is not a good insulator!!!! Post by Dave on 02/19/25 at 04:02:53 I just discovered something really weird. I have been adding some lights to my new (used) Jeep Wrangler. The first thing I discovered is that buying small rolls of colored wiring is really expensive - it is almost $13 for a 20' roll of 14 gauge, and I wanted 4 different colors. I discovered Harbor Freight has a wiring harness for trailers that is 25' long for $13.99 and it has red, yellow, green, brown and white - 125' of wire! You can split the wires as needed - I ran the red/yellow to the rear of the Jeep and the brown/green to the front, and I pulled off the white for use on another project someday. https://www.harborfreight.com/four-way-trailer-wiring-connection-kit-25-ft-64053.html?utm_source=google&utm_medium=cpc&utm_campaign=21901739258&campaignid=21901739258&utm_content=171677810582&adsetid=171677810582&product=64053&store=3150&gad_source=1&gclid=CjwKCAiAn9a9BhBtEiwAbKg6flN29ICoqHhwImCgoIXGEPQoO2m3tQMU7gwG1C_iezLsbMbrMme-vhoCUcEQAvD_BwE I installed a Lasfit control panel that had 4 switches and a relay box. The relay box wires extended to the right front frame rail at the firewall, and I used the new wires to extend the wires to reach the front/rear bumpers. When I attached my new wires to the wires coming from the relay box I stripped and soldered the wires together - I didn't have any heat shrink tubing so I cut a 1.5" piece of rubber vacuum hose glued in place with some RTV silicone to protect the bare wire in the soldered splice. I then wrapped both splices together with electrical tape and ran the wires through the frame rail (one pair to the front and one pair to the rear). Everything seemed just fine and I connected a set of white LED modular lights in the rear to use as backup lights. When I pushed button II on the bottom row of the switch panel the white lights came on. A few days later I installed RED led emergency beacon lights on the rear. My intent for them is to use them in the "steady on" mode in foggy conditions, and use the "strobe" function for emergencies. When I got them installed and connected to switch IV in the bottom row - the red lights came on.......but so did the white lights! When I pushed switch II in the lower panel the white lights came on - but so did the red lights! When the either lower switch was pushed ON - both lights would come on. The light corresponding to the switch was just a bit brighter than the other light - at first I believed I may have a ground issue. After checking the grounds and running a jumper ground wire nothing changed and that evidently was not the issue. The upper row switches (I & IV) ran to the front of the Jeep and were not yet connected to anything. When I hooked up a volt meter I discovered that with the switches OFF there was no power to either wire (like is should be) - but when I pushed either switch to ON I got 12V to both wires! Both the front and rear wires were activating the pair when any single switch was activated - however the rear wires did not activate the front, and similarly the front switches did not activate the rear. I decided I would go to the connections I had made at the Lasfit relay box wiring and my trailer wire extensions.......could the Harbor Freight wire insulation be faulty? I pulled out the spliced connections that were insulated with rubber vacuum tube, and I first cut off the electrical tape that was holding the splices together - and the wires worked as normal! Once the rubber vacuum tube was not touching each other the wires did not pass power across them!!!!! It turns out the rubber vacuum tube is conductive and was passing voltage across the soldered connections! I cut off the tubing and cleaned up the soldered joint, then applied liquid rubber insulation and silicone bonding electrical tape. The wiring now works as it should. (Good thing I had wrapped the tubing splice with electrical tape or it might have passed voltage to the frame!). So - don't use rubber vacuum line as electrical insulation.....turns out the darn stuff passes electricity nearly as well as it passes air!!! |
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Title: Re: Vacuum line is not a good insulator!!!! Post by ThumperPaul on 02/19/25 at 05:42:53 That is interesting. But I never would have been smart enough to try to insulate with vacuum hose. I’d just wrap 12ft of electrical tape around each little connection. That’ll do it!! Wire has gotten stupid expensive! I ran into the same sticker shock a few months ago when I wanted 14g in different colors. I only needed 2-3 ft of each color. I ended up at HF buying trailer harness wiring and separated it for what I needed it for. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by JOG on 02/20/25 at 07:28:57 Surprise,Surprise,Surprise! Rubber tubing is suddenly a conductor! The laws of nature, the laws of the Universe, have been rescinded! I wish I could have been a fly on the wall, watching the head scratching and the reaction to the moment when the troubleshooting identified the problem. WHUU? Rubber is now Conductive? When did they do Thaaaat? Did you try the ohm meter on it? |
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Title: Re: Vacuum line is not a good insulator!!!! Post by MMRanch on 02/20/25 at 09:03:58 Harbor Freight sells rolls of Heat shrink in different sizes (color coded even). Yes I've got all the sizes they sell but still need bigger size sometimes. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by ThumperPaul on 02/20/25 at 09:15:01 Because I don’t trust stuff or my work, I tend to overkill wire splicing. 1) Twist/Wad together 2) Solder 3) Install cute little heat shrink connectors (get in place b4 you solder) 4) Overkill with electrical tape That said, the little male/female bullet connectors are pretty tidy. Wrap those real good with electrical tape too! Lol. Hey! It works! ;D :o |
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Title: Re: Vacuum line is not a good insulator!!!! Post by verslagen1 on 02/20/25 at 11:08:35 don't let cheap get in the way of good. ;) years ago I thought rtv should be an insulator, hey it's rubber right? nope. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Dave on 02/20/25 at 16:40:52 Quote:
Not before using - but I did afterwards. If you just touch the meter electrodes to the rubber it doesn't show conductivity - but it does if you push on them a little bit. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Dave on 02/20/25 at 16:44:01 714D504855405775445049250 wrote:
I did all of the other connectors using the bullet connectors and insulators - but the wire splice inside the frame rails is not accessible once the job is complete, and I wanted them soldered and permanent. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Serowbot on 02/20/25 at 16:59:43 Get crazy and use two layers of shrink wrap :-? |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Dave on 02/20/25 at 17:36:26 2F392E332B3E33285C0 wrote:
I didn't have enough shrink wrap - I used most of what I had on Valentine's Day! ;D |
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Title: Re: Vacuum line is not a good insulator!!!! Post by MMRanch on 02/20/25 at 19:32:54 I used most of what I had on Valentine's Day! ::) :-? :-[ Do we want to know :-[? :-? :-? :-? |
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Title: Re: Vacuum line is not a good insulator!!!! Post by DragBikeMike on 02/20/25 at 19:35:40 Thanks for sharing. Who woulda thunk that rubber vacuum hose is a conductor. Good luck with the project. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by MMRanch on 02/20/25 at 19:35:44 OK , :-? I can see a hair dryer getting hot enough to shrink it ... But do we want to know what was it fastened to ? ::) |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Dave on 02/21/25 at 03:07:43 5D4F5D4F42515E5358100 wrote:
Cling Wrap......not Heat Shrink Tubing! :o https://www.youtube.com/watch?v=hPsaN3hOQFM [media]http://www.youtube.com/watch?v=hPsaN3hOQFM[/media] |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Serowbot on 02/21/25 at 15:41:41 102B2631202C37312A222F30430 wrote:
I didn't have enough shrink wrap - I used most of what I had on Valentine's Day! ;D[/quote] You know that's gotta' sting :o |
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Title: Re: Vacuum line is not a good insulator!!!! Post by SoC on 02/22/25 at 13:40:12 Ok, so why does it not work as insulator, the laws of physics have not been suspended. It turns out that not only isn't "vacuum hose" a suitable insulator for the application, it is rubber hose in general. But you will say rubber is an effective insulator, everyone knows that and yes it is, the issue is with hose and how it is manufactured and its compound. Is if you take a piece of most rubber hose and a VOM meter and you check resistance from the inside of the hose to the outside you will find there is in fact and in-effect completely resistance, i.e. isolation. Rubber is a fully effective insulator in that capacity. Now try an experiment that I can pretty much guarantee virtually no one has tried and place one probe of your VOM at one end of the hose and the other at the opposite end, making sure you are inside to inside, or outside to outside and what you will find is a circuit exists from end to end. Now if you wonder about this, and do some research it has mostly to do with the carbon that is used in rubber formulation, carbon is conductive and it is what makes rubber hose black. If you read up, it turns out that GM discovered this back in the day when they had problems with some aluminum parts in their cooling systems getting eaten by stray current. Interesting read if you look it up. It turns out you can get rubber hose without carbon in formulation, but it is not readily available and is pretty expensive. I discovered this phenomenon on my boat actually which has an aluminum saildrive which requires total electrical isolation from the engine itself. It turns out Volvo provides the OEM hose from the engine water pick-up in the sail drive to the engine water pump (yes I realize it is a stupid design to pull the cooling water thru the sail drive, but it cools the drive also), the OEM hose is special rubber formulation. Over time salt from the raw sea water it draws gets deposited on the interior walls of the hose and this creates a more conductive pathway. But that's another story. Take away is rubber hose is basically conductive along it's length and current will pass along it, but not through it. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Dave on 02/23/25 at 03:07:25 2B2A2F3D3E3D322F37355C0 wrote:
Im this case the electricity was passing through the tubing. The bare wire was positioned inside the tubing and was passing the voltage through the tubing, across to the other piece of tubing it was taped to, and then to the other wire (Thankfully I had fastened them together with electrical tape or they might have passed the voltage/current to the frame and created a short). When one wire was energized it passed sufficient voltage/current through two layers of the tubing and it would operate the other set of lights - which was not connected to the other wire. This situation occurred when either switch was energized - however the lights that were not directly connected were slightly dimmer (which indicates there was some resistance in the tubing). I will do a test with my Ohmeter and post it later today. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by zevenenergie on 02/23/25 at 04:54:01 It is better to get a real one. You can buy them online in all the values [ch8203][ch8203]you want. http://https://i.imgur.com/1T2RocUt.png The advantage over a rubber hose is that there is a barcode on it from which you can deduce the resistance. I have yet to see the first rubber hose with such a code. I hope you are not civil servants because this might look bad on your weekly report. |
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Title: Re: Vacuum line is not a good insulator!!!! Post by Ruttly on 02/24/25 at 14:52:16 It always sucks learning the hard way ! |
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