Safest Way to Contain Spliced Lamp Cord

Question

I am interconnecting some strip lights in a closet. They are linkable LED fixtures which each come with a connector cable to link, optionally, to additional fixtures. The connector cables are a bit short for what I have in mind, but I need to use their ends because they have special connectors to link the fixtures and maintain correct polarity.

The connector cables are 18-2 SPT-2 lamp cord. I have a spool of the same type of cable. I am planning to cut the connector cable in the middle and insert an appropriate extension length from my spool. My plan is to splice them using some 22-18 butt splices, then heat shrink them with 3/4" tubing. I will ensure the splices are solid and the polarity is correct. Beyond this, what should I do to make sure this setup is safe?

None of this will be behind a wall. The strips will be against the wall, on their mounting brackets, and the cabling can be secured however. If nothing else, I'll just be using cable staples. I could also run all or some of the cabling through conduits, bracketed against the wall. Or I could simple put the spliced areas within junction boxes. Any suggestions for the safest way to do this are welcome.

I realize there may not be a code-approved way of doing this. The cables will not be in a place where they can be routinely touched, and if I were to move out of the house, I would take all of this stuff down, except for the first of the linkable fixtures which was installed with a junction box by an electrician (it is controlled by a light switch).

If you believe there is no way this can be done without a moderate risk of fire, it would be very helpful to hear why you think so.

Update: This particular line of products now has longer lengths of linking cords available. As a result, no splicing needs to be attempted.

EDIT: This is obviously NOT a duplicate question as erroneously suggested as "What size heat shrink tube is required?" and "How can I safely do something?" are completely different questions.

Answer 1

This family of lights uses all 120v wiring which means the full weight of NEC applies. You cannot "freestyle" splices in the manner you are talking, you must use listed products, which those cheapie butt splices probably won't be. They do exist, but O'Reilly Auto doesn't sell them and they don't use $5 crimp tools either.

So here's how you handle "the cord is too short". Legally, splices can only be inside junction boxes. The American gold standard way to splice inside a junction box is with "wire nuts" - for two 18ga. wires I would use the blue or gray ones. Do not use stabs, they are not rated for 18ga.

If GE sells a listed method to attach their special connectors to your lamp cord, go for it. Otherwise you can only use it between junction boxes, which means 2 junction boxes. If you want to do it in one junction box, then buy 2 cords long enough to give you 8" slack inside the box, and splice there.

But I have to say: why on earth are you using this family of products? Don't get me wrong, GE's quality is first rate, but why wrestle with 120v products when you can get the same thing in 12v that's much easier to work with.

Also, these prices are way beyond insane, at least 3-4 times what I've seen in quality 12v products. IKEA has a broad selection of 12v products at sensible prices. 12v makes the products cheaper because they do not need expensive voltage converters in each lamp. I buy cheap Chinese LED strips for $7 for a 16 foot roll, I mention that only to shake you out of a notion that $60/foot is a normal price for these things.