Just use UL listed parts with large enough wire and you are GTG

There's another possibility that might solve my problem.

The extension cord is 15 feet long, but the length from the first outlet to the last outlet is only 3.5 feet.

I need the first and last outlet to be spaced 15 feet apart, with the remaining outlet midway between the two.

Can I safely add wire between the outlets so that the outlets are about 7 feet apart? That way, I'd only need to use one extension cord.

You can use a purchased cord as a source of parts for making what you want.

Brickeyee,

Do you think I can cut off the plug and the last outlet on one cord, and insert it between two of the outlets on the second cord? I was thinking of doing that, but didn't know if it was possible, since the plugs have fuses and I would be cutting one off.

Thanks so much for your help thus far.

You cannot make a splice except in an approved device.

There are blocks with receptacles on them that can be wired into a cord.

The block is an approved device for making the connection inside (it will have strain reliefs and some method of making the electrical connection.

You might want to do some searching on holiday lighting sites. Several seem to sell the parts necessary for custom extension cords. Will they meet any sort of standard set forth by governing bodies, probably not. Will they work, probably.

I'd suggest being careful to watch the total current draw on a custom made cord and be damned sure to plug everything into a GFCI protected receptacle.

Here is a link that might be useful: Making Extension Cords

"Will they meet any sort of standard set forth by governing bodies, probably not."
As a cord and plug connected load there are not al that many standards.

NEMA is for items manufactured for sale.

Using UL listed components is all the NEC really can require.

Millions of folks have made all sorts of cord and plug connected equipment without significant problems.

Up until about the past 2- years, every HAM (amateur radio) operator made their own RF transmitter, and many other pieces of gear.

About the only thing you can screw up on this is overloading the cordage you use (to many watts of lighting for the conductor size and temperature rating).

Mike K, that's EXACTLY what I'm looking for. Thanks so much. I have it bookmarked for easy reference again and again.

Brickeyee, thank you for all your prompt replies.

People here are so helpful. And I always feel that no question is too elementary.

Thanks again, everyone.

Brick,

I know that certifications are for products that are designed to be sold but there's an implication of safety that goes along with it. I'm not saying that a home made cord (and I've made them) are unsafe but they could be for someone who doesn't understand what they are doing or uses it in an inappropriate manner.

The website I referenced describes making extension cords with zip cord and what they call "vampire" plugs - they simply pierce the insulation to make contact with the conductor. That's not unlike those inline, rotary lamp switches but most people aren't putting table lamps in the front yard. The websites I looked at sell SPT lamp cord to make these "extension cords". I don't even know if that type of cord is even suitable for outdoor use.