NFPA 70E: Electrical Safety for Portable Cord- and Plug-Connected Electric Equipment
Portable equipment and portable cords are designed/built to be used with many safety considerations in mind because (among other reasons) materials have their limits.
Take, for example, the common practice of lowering an impact driver or other power tool from a ladder by its cord, which is banned by Sec. 110.9(A). This appears to cause no harm. The cord didn’t come apart and looks the same as before. But it’s not the same as before. The cord actually stretches due to the weight, and this stretching reduces the integrity of the insulation. Maybe the effect is insignificant the first time, but keep doing this and you will have a cord with significantly compromised insulation. Remember, a portable cord is not a utility rope.
Another effect that occurs is when the “careful” worker (who is not depending on the plug of the tool to stay inserted into the cord receptacle) wraps the cord around the tool. And if he’s really “careful,” he ties that cord into a knot. This exceeds the bend radius of the cord, permanently damaging it. A few microtears here and there, and the cord is not nearly as safe as it should be. Use a properly tied rope, a rope and carabiner system, or a lanyard of suitable length to lower the tool.
Another “safety” practice is to secure a cord with staples or wrap it around a structural member to keep it out of the way. The main problem with this “safety” practice is it ensures you damage the cord. This practice is also banned by Sec. 110.9(A).
But the idea of securing a cord out of the way so that it’s not a tripping hazard, and it’s not damaged by being walked on is a good idea. Others have had this idea too, which is why there are products made specifically for routing, securing, and protecting portable cords. If you are going to work in areas with foot traffic or vehicular traffic, obtain such products ahead of time. Keep in mind also that if you are using an overhead solution, you will need to allow for two vertical runs of cord length to accommodate that. Don’t try to use a 50 ft cord with cord trees if the work location is 40 ft from the receptacle. The same logic applies to routing around the perimeter of a room or other area. Don’t plan in terms of straight line distance, plan in terms of the route the cord will take — it’s similar to planning what length of conductor you need for a branch circuit.
When purchasing portable cords, always purchase a contractor-grade (e.g., heavy-duty) cord, and ensure it has a grounding conductor. This last bit will ensure you always comply with Sec. 110.9(B), which requires using a cord with a grounding conductor any time you use grounding-type equipment. If you don’t have a cord without a grounding conductor, then you can never choose the wrong cord.
Before putting a cord away, visually inspect it for external defects, such as loose parts or a chunk missing from the jacket. Also inspect it for signs of internal damage; if the jacket is pinched or crushed, the cord probably has internal damage. Performing these inspections before using the cord is required [110.9(C)(a)]. But by performing them after use, you have time to address any issues before you need a cord again — and it's the only one you have.
One incorrect way to fix a cord with damaged insulation is to wrap phasing tape around it and call it good. That is not a good way to fix a cord. First of all, phasing tape doesn’t offer the same protection that the jacket insulation does. And if the insulation is damaged, you should assume that what’s under it is damaged also. There are only two correct solutions:
- Remove the cord from service [110.9(C)(b)], and discard it.
- Remove the cord from service [110.9(C)(a)], cut and remove the damaged part, and attach new ends (male and female connectors) to the remaining pieces if they are long enough to be useful.
How should you store portable cords? Tossing one into the bottom of a gangbox is an obvious mistake. A great solution is to use portable cord spools. These properly wrap the cords in a way that doesn’t exceed their bend radius, and they allow for easy cord laying because there are no knots or21257535 tangling.
Another solution is to use an “air spool”; you simply make cord loops on the floor. How big should the loops be? Just let the cord relax as you make these and you won’t exceed the bend radius. If you go this route, consider putting the cord into a suitably sized drawstring bag. In all cases, keep the cord loose. Binding it with cable ties, even if you do so in figure eight fashion, can damage the insulation. Binding it with any kind of tape could leave a conductive film on it while also leaving the cord sticky.
