Milwaukee recently launched their “Lineman’s Underground Knife,” aimed at – you guessed it – power utility workers.
The new Lineman’s Underground knife, 48-22-1929, is designed for stripping multi-layer underground distribution cables.
Its blade is designed to stay sharper longer, and it comes with a durable blade cover that stores in the handle for convenient and safe keeping. The handle is said to be built for all-day comfort, and the knife is sized to fit into a tool pouch for easier storage.
The blade is made from stainless steel and measures 1.75″ long, and the handle is 5.25″ long.
Buy Now(via Acme Tools)
Southwire’s cable knife cover also stores in the handle, I think it’s something like 30% cheaper. Wonder how they compare otherwise.
I think that blade cover will get dropped — I’d say “all the time”, except that all it takes is once not seeing it (it’s black!) or being able to retrieve it, and you’re left with a very sharp, unprotected tool. I would rather have seen Milwaukee develop some kind of retractable cover/sheath, or some other solution that shows they’re aware of the real-world environments that this pro-tool will be used in.
As these aren’t insulated (and using a knife on an energized cable is a special kind of nuts), I see no advantage here over any of a zillion razor knives with retractable & replaceable blades. Nicking a conductor is, I believe, easier to avoid with a sharp knife than a dull one, too.
I’m not sure what utility workers use with URD cable – but these sorts of knives have been around for decades. Ones like the Hyde 20555 come to mind. There are also other large cable strippers like this Klein:
Or the (pricey) Greenlee P2095 and P2096
I’ve also seen a gizmo (at J Harlen) that winds up the neutral wire in a way that strips the insulation. It (Part # USCS001) looks to be a hook that you chuck in a cordless drill.
Looks like a standard splicing knife to me. Not sure why they’re intent on creating their own wheel. (Definitely not a reinvention.)
As someone very experienced in terminating cables, I’d never buy this knife. It’s way too thick. I’ve tried them all and I’ve worked with the same cables that linemen work on (and worked WITH plenty of linemen). Not a week goes by that I’m not terminating cables of some kind. This week it was doing twenty four 500 MCM jumpers for a big starter which is kind of a typical week. I do all kinds of low (600 V) and medium voltage (up to 35 kV) cables all the time. I’ve been through training classes by 3M and T&B.
The standard technique once you get beyond “house wiring” sizes (say #8 or smaller) is to score a radial line all the way around the cable (a ring) and then a straight line down the cable to the end. Keep scoring the long line until you just touch the conductor or the next layer. Then grab on and open it up along the scoring lines and peel it all off. That’s the theory at least. It works fine with common 600 volt insulations like PVC and nylon.
With very flexible insulations like CPR (Chlorinated polyethylene rubber) or TPU (thermoplastic polyeurothane) that you get with mining, submersible pump, and SO cord, it is so tough and flexible that generally getting the peeling started is the problem. If it’s a big cable you can cut a strip lengthwise. In smaller ones just make it a wedge. Either way the big problem is getting leverage on the cable to peel it apart. Use a pair of needle nose pliers to grab it on smaller cables or a pair of hoof nippers on bigger ones to twist it around the tool and apply lots of leverage to get it to peel apart.
On hard insulations (XLPE) like URD I’ve found the best technique is to take a pair of 14″ channel locks and grab around the insulation and twist it. It will tend to either break along the radial score and come off or it pushes against itself and breaks apart at the straight score. Grabbing it like the flexible stuff just breaks off chunks.
Either way…you can see a theme here. Scoring and cutting is the name of the game. The thinner the knife and sharper, the better it works as long as it is stiff enough to go through. Sure you can use a fat edge so it doesn’t dull easily but then it drags through the material and cutting is a bear. That’s the problem with the cable splicing knives. Also no matter how hard you try, you are GOING to hit either some kind of metal shield or the copper cable itself. and this is going to nick and dull the knife. In the past I used a hawk bill knife and just sharpened it a lot. Now I just use a good quality utility knife and carry a pack of blades. The hawk bill is definitely stiffer and makes it easier to get through the cable when it is sharp but the beating the knife takes means I can’t terminate too many cables before I have to stop and sharpen it. It’s just not worth the time lost.
Hence the closest fixed blade knife is either the Klein hawk bills or the “cable skinners” knife that you get in the set that they sell is the gold standard. There are tons of those “lineman knives” out there but all they’re good for is things like cutting rope, not cables.
To be fair, the knife I currently carry for this work is a Milwaukee utility knife. I like the one that has 3 extra blades in the knife. When I’m skinning out cables, I go through a LOT of blades for obvious reasons.
There is a really stupid safety agenda out there to ban utility knives. I have tried every gadget and gizmo on the market. They work in certain isolated cases. For say #10 or smaller it is far simpler and safer to just use a dedicated stripper. The combination tools compromise the stripper function every time. You can get a hook-and-blade type thing that works up to around #1 too but this tool has a big problem and many “gadgets” have the same problem: you have to set the blade depth very accurately to get it to work (cut all the way but don’t nick the copper). The failure is that the conductor isn’t exactly centered in the cable with a single conductor so the thickness varies (miss on one side, hit the conductor on the other). The other problem is that in multiconductor cables the thickness varies as the molded insulation fills in the “grooves” between conductors. This doesn’t happen with a knife because you can feel how deep you are cutting and stop. The hard insulation “pencil sharpener” style cutters work awesome IF again it is very uniform thickness AND only in very hard insulations like URD. In everything else the tool just gets caught in the soft insulation and never cuts anything. Nicking conductor is a huge no-no especially in higher voltage cables and even in low voltage, particularly in fine strand cables where it’s easy to cut whole strands off so these gadgets are extremely limited in their use, when they work at all. So the whole idea of knife banning is a big fail when it comes to electrical work. The biggest improvement we’ve had in years is all the improvements in the materials for cut-resistant gloves. Used to be a “cut resistant” glove meant a chain mail style fish gutting glove. Now we can get knit gloves that have lots of dexterity and plenty of protection against slash wounds. Poke resistance (from a wire) still isn’t there though. A level 3 cut resistant glove will easily stop utility knives without a concerted effort to hurt yourself (multiple passes cutting the same spot).
Great post. I use some of the spinner types (You called gadgets), the trick to those is to set them shallow then bending the wire in the score and it breaks the insulation. That doesn’t work well on soft wire like silicone or the insulation on coax so you can use a quick stripper(the Irwin type) to pull off the insulation…obviously that’s for much thinner wire than the majority of your post mentioned, RG6 being the largest a Irwin quick stripper will work on.
Dude, thanks for that write up! Great info and detail.
Paul. I’ve saved your entire post. Appreciate it when someone who has figured it all out the hard way shares their experience. Cheers !
Paul….wow.. you sound like the real deal…thanks mano
Hmmm. First context: a) this is India. b) we have 240v, and we have 3-phase domestic supply.
I suppose the US term would be utility worker, as mentioned above. Actually, the guy is a fairly senior engineer on the street. We got to know him so we can call him if we have a problem (see context “a,” It’s how stuff works here).
We had a burnt-out (connection worked loose) incoming phase connection. Our guy replaced the old-fashioned ceramic fuse-wire-carrier block and reconnected. His knife was a “stanley-knife” (utility? I’m a Brit, to add further linguistic confusion!) blade taped to a piece of wood.
Using that knife and a pair of insulated-handle pliers, he stripped and reconnected the incoming cable. Live.