12/3 SJ Cable Repair

[ship]

20+ years ago I read a book (amongst many) describing a linesmen's method for cable splicing. As opposed to where I work in early methods of just tapping over a cut in cable - cut to copper, inpected or not etc. I developed a method/standard for cable repair which has worked. Unfortunately 20 years ago I loaned that book to someone and it's gone without me noting or remembering it's title.
Sub-Note, wraps of glued volcanizing tape is based on stretched cable jacket thickness in re-producing the outer jacket of a cable thickness. There is also other details on other cable types and repair which were not important to the question. Below was sent to a on-site Crew Chief about production cables in use - repairs to them.... Would they prefer electrical tape repairs in not knowing who did it or inspected it in doing so?

The Method I established for 12/3 SJOOW cable:

Any cut on a cable is inspected before repair.
-Any cut to the outer jacket of the cable more than 1.1/2" long or 1/2 the diameter of the cable is deemed non-repairable.
-Any cut into the inner conductor cable insulation exposing copper strands (except on the ground), is deemed non-repairable.

1) The outer jacket of the cable in the area of the cut is first cleaned with Naptha so as to clean and prep the surface for adhesive.
2) Red Liquid Electrical Tape is lightly brushed into the cut in the outer jacket to mark the cut, it's inspection and lightly bond the outer jacket together without bonding it to the inner conductor insulation.
3)3M Scotch #2141 Rubber/Neoprene Adheasive is applied to the outer jacket of the cable approximately 2/3 the length of the cut's ends or at least 1" longer from each side for a small cut.
4) 3 tapered layers of 3M Scotch #130C self vulcanizing rubberized electrical tape is bonded to the outer jacket of the cable for water resistance and di-electrical insulation.
5) More Rubber/Neoprene adhesive is added over the rubberized electrical tape.
6) Two layers of 3M Scotch Super 33+ is applied over the rubberized electrical tape for abrasion resistance.
7) A thick coat of 3M #14853 Skotchkote Electrical Coating is applied over the Super 33+ to help in weather and abrasion resistance and prevent tape peeling.


Thoughts, other than many of the above products listed above are not for use in some states.

 

[Gage]

I've always used the liquid electrical tape, followed by an adhesive lined heat shrink of appropriate size (given I can easily remove an end from the cable and slide it on). Probably not as sound as your method, but I haven't ran into any problems with it.

I apply the same go/no go rules though. Break can't be too big, and can't affect the insulation on individual conductors.

I've also experimented with laying a bit of abrasion resistant automotive wire loom on there, followed by another piece of adhesive lined heat shrink. Verdicts out on weather that really does anything though. The "lighter" repairs don't seem to fail, and the extra layers tend to make a stiff point.

 

[ship]

Much research on my part... 20+ years, and thanks for the reply in advancing the concept thoroughly researched and now under discussion. Consider my below responses by way of tried, but open disussion in general. Thanks, in looking to improve on what we all do. This in realizing to anyone in the field... a piece of cable with just some electrical tape over a section of it... raises our hairs!

Who taped over what???? A proper in-shop repair of quality says such a repair to a cable was done by a trained shop supervised person and program for that repair. There was as above, some inspection of the problem and intent if safe to make a proper repair in decision of the cable's deletion from service or a safe repair. A good start to a protocol for cable repair.

Liquid Electrical tape should be considered no better than electrical tape as per how we all know how well it seeps and flows in higher temperatures. It does not bond to the cable in any way weather/water or heat resistant given heat or flexing.. I somewhat use it for bonding an outer jacket together, but more because it will not prevent the outer insulation of conductors from really sticking to the outer jacket once applied. Also in Red, it marks a repair. Liquid E-tape has no real gluing strength to cable, other than within a well wrapped repair. Too much of it prevents the bonding of the repair adhesive from doing it's job.

Adhesive lined heat shrink is literally a hot glue added to a heat shrink tubing. How well does hot glue bond with a rubber or even plastic jacket of a cable? Adhesive lined heat shrink say's it's weather resistant... but it would depend on what it's bonding to. If hot glue bonding to dirty cable, or even clean cable.... how well does hot glue bond with that cable once flexed?...

"laying a bit of abrasion resistant automotive wire loom on there, followed by another piece of adhesive lined heat shrink." Pictures of the wire loom concept. Interested in seeing what you are doing. But on the other hand, again hot glue sticking to heat shrink outer layer of even adhesive lined hot glue is testable but really doesn't bond. (Good efforts on your part in doing something.) Water resistant it says it is, but is not flexible in the bond not a bond given the hot glue does not bond to what it is shrunk to. And with flexing on cable the heat shrink not bonded expanding thus no longer water proof even if hot melt glue attempting to bond to the cable.

Main concept to look into is the repair method bonding to the repair. This be it adhesive lined heat shrink I often also use, or some form of tape. Also in this concept is the use of the turn of last century concept of using Friction tape - with the glue advised above. Friction tape given cloth and rubber would work with rubber adhesive in theory as sort of a fiberglass like filler for support or a hole in a cable.

You have to bond the cable to be repaired to what you are repairing it with. Naptha will clean and prep rubberized say SJ or SO cable for bonding to a glue. It I think - but could be incorrect, will also clean/prep with a thermoplastic type of cable enough to clean and prep the cable for repair. Perhaps another chemical to prep SJE or say SJT types of cables. Denatured alcohol at the very least to prep the cable for glue. Limited value. Other concepts tried.

Above rubber/neoprene adhesive. In my cable repair kits to tours I even supply small tubes of wet suit repair adhesive for this part. (doubt ever used.) Overall goal is to glue bond either the vulconizing tape to the cable, or in the case of heat shrink - I prefer for shop repairs... bond the adhesive lined heat shrink to the repair.

You have to clean/prep the dirty cable surface to accept a glue to it before just adding a heat shrink or self volconizing tape to a cable surface. You than need a glue which would bond the rubber to rubber, or hot glue to rubber if expecting a bond. Otherwise this is not a bond.

After that, yes I also prefer adhesive lined heat shrink repairs. If glued, and with cleaning/prep for bonding glue to the jacket of the cable type, they never need attention.
One is always mindful of tapering the repair so that the full thickness of the outer jacket over the cut is reproduced over the cut. This is tapered so as not to become an obstruction in pulling the cable across something, but also the thickness of the cable jacket repaired is the same in thickness.

 

[Gage]

Ship,
I see I'm not the only one lurking around the booth after hours.

As far as the hot melt in the heat shrink goes... yes, I have noticed its lack of adhesion on certain materials, however, I haven't had problems with it on rubberized cable... yet (but boy has it reared its ugly head on other things). That being said, I plan on taking some inspiration from your method, as I'm always looking for improvement.

Beforehand I always clean the affected section of the cable with an appropriate solvent (usually denatured alcohol). Unfortunately, both naphtha and denatured alcohol is next to impossible to buy in California as a consumer now. I'm down to my last few bottles of denatured and am clean out of naphtha, I can't even buy it as Coleman fuel anymore.

I've had plans to test E6000 as the adhesive between the heat shrink and rubberized cord. I've had good experience with it on other repairs, it always remains incredibly flexible, is temperature resistant, and has very good dielectric properties. Need to see how well it adheres to both materials though.

I don't have any of the correct wire loom on hand for an accurate picture of my experiments, but I'll scrounge up a substitute in the next few days to make an impromptu example. I will also look into trying friction tape, as well as a 3M glass-cloth tape I recently discovered that's backed with a heat-activated rubber resin compound.

Overall I have a lot of experimenting to do... and thankfully the time to do it. As always, I'm very appreciative of your willingness to share information based on your experiences. As a young man who's just barely got his footing in "real" theater, it's always been my goal to learn whatever I can wherever I can.

I'll continue to post my findings if I make any good progress.

Thanks,
Gage

 

[jtweigandt]

Ship,
I see I'm not the only one lurking around the booth after hours.

As far as the hot melt in the heat shrink goes... yes, I have noticed its lack of adhesion on certain materials, however, I haven't had problems with it on rubberized cable... yet (but boy has it reared its ugly head on other things). That being said, I plan on taking some inspiration from your method, as I'm always looking for improvement.

Beforehand I always clean the affected section of the cable with an appropriate solvent (usually denatured alcohol). Unfortunately, both naphtha and denatured alcohol is next to impossible to buy in California as a consumer now. I'm down to my last few bottles of denatured and am clean out of naphtha, I can't even buy it as Coleman fuel anymore.

I've had plans to test E6000 as the adhesive between the heat shrink and rubberized cord. I've had good experience with it on other repairs, it always remains incredibly flexible, is temperature resistant, and has very good dielectric properties. Need to see how well it adheres to both materials though.

I don't have any of the correct wire loom on hand for an accurate picture of my experiments, but I'll scrounge up a substitute in the next few days to make an impromptu example. I will also look into trying friction tape, as well as a 3M glass-cloth tape I recently discovered that's backed with a heat-activated rubber resin compound.

Overall I have a lot of experimenting to do... and thankfully the time to do it. As always, I'm very appreciative of your willingness to share information based on your experiences. As a young man who's just barely got his footing in "real" theater, it's always been my goal to learn whatever I can wherever I can.

I'll continue to post my findings if I make any good progress.

Thanks,
Gage

Just curious.. what properties does denatured give you that isopropyl wont? And if you are absolutely intent on having ethanol (which is what denatured is with contaminants added to make it undrinkable) Just go down to the liquor store and get thee a bottle of everclear. Its' about 95% ethanol.

 

[Gage]

Just curious.. what properties does denatured give you that isopropyl wont? And if you are absolutely intent on having ethanol (which is what denatured is with contaminants added to make it undrinkable) Just go down to the liquor store and get thee a bottle of everclear. Its' about 95% ethanol.

IPA unfortunately just isn't as strong. I still use 99% IPA for many applications, but it hasn't provided satisfactory results on cables in the past. Everclear does work, as well as other forms of non-denatured alcohol, but because it's fit for consumption, the taxes applied to it make it double or even triple the price of comparable solvents. Maybe not an issue if I was using small volumes, but I will often purchase gallons at a time.

The only other products I've found that clean as well as the solvents above are citrus-based cleaners. Only problem is they leave an oily film behind that is unsuitable for this application.

I would love to find something that works just as well and is easy to get ahold of, but I need to do some more searching.

 

[JonCarter]

If it's a little nick, tape it up. If it's real damage, cut it & put on a pair of connectors. So it was a 50'? Well, now it's a 40' and a 10' jumper. Problem solved.

 

[Crisp image]

If it's a little nick, tape it up. If it's real damage, cut it & put on a pair of connectors. So it was a 50'? Well, now it's a 40' and a 10' jumper. Problem solved.

Agree here. For me if it is under 5m (16ft) 240v I will bin it before repair. it is not worth my labour and parts to repair when a new one is not much more than the fittings. Other cables might be cut into shorter lengths but only when I get the time or have a special project. Longer lengths get cut and fittings added to them. Here in Australia the only really accepted repair of a 240v cable is heat shrink. Electrical tape can be removed easily without tools which means any idiot can get a shock if they choose to repair the cable. (Any 240v cable that is has been cut to the cores (exposed copper will not be repaired unless it is cut and fittings added)
We have a test ang tag system which is widely adopted as best practice. With all tests the item is only safe at that point. Once it leaves my hands it could be compromised and made unsafe. The test frequency is determined by the industry and environment the cable lives. Construction is every 3 months, in the theatre is every 12 months and in office environment it could be 2 to 5 years. Something like a fridge that does not move will be a 5 year test.
With 240 + v play it safe
Regards
Geoff

 

[ship]

Interested in the test tag, but as with cables on my part, I'm in the hundreds of cables of each standardized size needed for shows to pull. So a say 49' cable might be acceptable, but a 48' would not. I standardized 18" from the end a corporate identifying heat shrink on the cable years ago so as to ensure cable length.
E-tape on a cable makes me suspicious, all people where I work are trained to be suspicious of any E-Tape on a cable. Why is it there, and what is under it? As above the specified repairs to cable meet all the requirements I believe for wire splices. Vulconizing tape glued to a prepped for adhesive and cleaned cable. More glue to bond E-Tape to the rubber tape, than an outer coating of electrical top coat to seal the E-Tape.

Simple repair to a still servicable cable takes about 1.5 minutes. The glues etc. fairly cheap given the amount of repairs that can be done with the process. Glue pots for the cable adhesive has gone way up in cost, but if time one can with a blow torch clean them out in cleaning... It's a program for cable repair for simple fixes. Cost on in discussion, 12/3 SJOOW cable is on the cheap around $1.27 per foot. Replacing a 50' cable costs more than repairing it as long as only a few as normal simple repairs.
This given the repairs are proper and well done. I prefer a heat shrink repair, but only if prep of the cable and glue is done to the cable. Otherwise even heat shrink repairs to cable is no better than, or worse than the E-Tape repair.
E-Tape in a non-air conditioned environment tends to loose it's adhesive qualities and just seep/flow/fall off. Become a gooy mess for a repair. Heat shrink, even adhesive lined heat shrink, unless glued to the cable tends to re-epand in not bonding to the cable it's applied to when flexed over time.

Ideal is cutting the cable to a shorter length and also done by us. But if within code compliant as not mentioned above... cable markings are still valid, there must be cable jacket markings on the cable. A plug/connector combination is like $15.00 at OEM cost as a general figure for necessary commercial grade fittings. Glued taped or heat shrunk inspected repairs are safe and cost effective as long as within training guidelines. Above mentioned, but interested in much more discussion.

As a starting point though, is what program I did for cable repair's... re-read what I do. As a goal for cable repair, some standard to strive for?

 

[JonCarter]

I agree that a cable repair should be as good or better, both electrically and mechanically, than the rest of the cable. If I were running a rental house I would supply exactly the number and lengths specified on the order. The odds & ends would be sold "as is, where is" to anyone who wants them or donated. My experience has been primarily in community theatres and summer stock, and as such a few odd-length cables always seem to find a use, and new cable is expensive!

 

[Crisp image]

We don't repair many cables but we pull everything out of the theatre(s) every year and test and tag EVERYTHING mains voltage. It takes our team about 2 weeks to do our annual maintenance which includes test and tag, cleaning all fixtures, pin checking audio and dmx cables and cleaning them all too (we use shellite).
Repairs mentioned above usually need to be done by a "Qualified" person. I can replace plugs and sockets but anything other than a little heatshrink on the cable I can't do.
If you want to know more about the test and tag standards google it.

 

[almorton]

Test and tag sounds not dissimilar to "PAT" in the UK, portable appliance testing, which involves, amongst other things, inspection of all cables, connectors and casings for physical damage, electrical testing of grounding where applicable, and many others such as can a pen be poked into the appliance. The frequency of testing is risk based - as suggested, a fridge doesn't need to be inspected as often as an extension lead or a lantern that is regularly being rigged and derigged every other week, or a power tool in daily use. There's also the ongoing "testing" that every time an appliance is used, you give it a once over for obvious damage anyway.

 

[ship]

https://en.wikipedia.org/wiki/Shellite

• An Australian form of Naphtha
• Shellite (explosive), British explosive filling for armour-piercing naval shells of the 1920s to 1930s.
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• Assuming cleaning one's cable with a Naptha like health hazzard like product solvent I use to prep cables only so as to clean the cable and prep the rubberized jacket for glue... Cleaning a cable with it seems risky and damaging to the cable if done yearly should be a health hazzard to you. Much less it's going to rub off the at least in US mostly printed ink markings on the cable required for use.
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[soundman]

@ship Does the shop have repair kits to send out with shows for cable repair? Something so specific might be hard to source from a runner

 

[ship]

Yes hard to source and yes cable repair kits which have evolved over the years. The largest problem was the Naptha cable cleaner and Cable to tape glue. Denatured alcohol solvent is fine for the most part to prep the cable in the field for prepping the cable for glue, and always a few packets from lamps about. Neoprene diver repair glue tubes were provided also for the actual glue of the rubber electrical volcanizing tape to the cable.

Cable repair kits have evolved. It's found over the last 20+ years, nobody is really repairing a cable properly with the products provided on the road. No time, at best E-tape repairs. Perhaps once in a while when allwed to repair to repair a feeder cable cut (with much more tape rules). It was a way to do it, but I doubt much if ever used. I'm fine with that in rathering do do a repair in shop as opposed to over the years, less and less touring people have been trained by my department for repair.
During the pandemic I let my assistant, a touring person re-design the cable repair kit. It became more focused on chain hoist cable repair and Soco cable repair.
It was noted as important that the cheaper four point indent crimp tool Bucannon style crimper would not crimp then new 14ga crimps we changed to. Had to bite the bullet in 5x more expensive crimp tools given the new type of hoist cable normal problems.
Less and less about actual cable repair, instead about replacement plugs and stuff like that. PowerCon Blue panel mounts and the in-line are a bad design... Lots more included in the touring cable repair kit.
I wanted to start including a solder station into cable repair kits given the amount of LED tapes are involved with shows. Did so on some, but at some point we have to cable/fixture repair include a road case for that.
Moving more towards that these days as opposed to a 40# cable repair box. I know for installs I normally do, having a packed install road box is very useful for all conditions I come up with. If truck pack is able, I think in the future is a road box for cable repair.
Just today, moving lights repair head came to me in asking how to break the thin dichroic lens pre-scribed but not pre-cut. Split lens appairently for a fixture, but the lenses are not split as replacement part. Another thing to add in pliers to split lenses to add to repair kit? Growing challenges and changes as to what to repair an on-site crew might need.