Electrician's Knife: How to Choose One (Hawkbill, Sheepsfoot, Hollow-Ground) and the Japanese Denko Knife
Quick answer: which electrician's knife?
- For slitting and peeling cable jackets (NM/Romex, VVF, SJ cord), pick a locking knife with a blunt or curved tip: a hawkbill holds the cable, a sheepsfoot has no point to stab with (American Knife & Tool Institute).
- The Japanese answer is the "denko knife" (電工ナイフ), a short, thick-bladed folding or fixed knife (Mynavi). It is a designated tool for Japan's second-class electrician skills exam, where exam guides advise against using a box cutter instead (Panasonic, Agaroot).
- Folding, pocket-size: TSUNODA (TTC) EK-72, 72 mm hollow blade, 107 g, lock and strap hole.
- Folding with a wrench: TAJIMA DK-FKMU, 68 mm blade plus a 17 × 21 mm box wrench.
- Fixed blade you can strike: TAJIMA DK-TN80, through-tang, hammer end cap, deburring groove.
- No knife at all: Japanese electricians also strip VVF sheath with electrician's scissors, or skip the blade with a VVF/cable stripper.
- None of these knives is insulated. De-energize first; for live work you need an IEC 60900 (1000 V) tool.
This guide explains the blade shapes electricians use, what "hollow ground" means on the job, how a Japanese denko knife differs from a utility knife, how to strip a cable jacket without nicking the conductor, and which of the four Japanese tools we stock fits which job. Facts come from the American Knife & Tool Institute, Electrical Contractor magazine, TSUNODA's and TAJIMA's own pages, Japanese exam guides and real electricians' forum threads. Sources are at the end.
Safety note: this is a general guide, not training. Turn the circuit off and verify it is dead before you cut into any cable, and follow your local code.
What an electrician's knife is for
An electrician's knife is mainly used to open the outer jacket of multi-conductor cable so the insulated wires inside can be pulled out, and on some jobs to strip conductor insulation, open boxes and trim. AKTI's guide for electricians names the three blade shapes you see most, and Electrical Contractor magazine adds the utility, snap-off and folding body types:
| Blade shape | What it does well | Trade-off |
|---|---|---|
| Hawkbill (hooked) | The curve keeps the cable from slipping out while you pull the blade along it (AKTI); Electrical Contractor says it gives controlled cuts with less risk of damaging conductors or insulation | Awkward for straight slicing on a flat surface (our view) |
| Sheepsfoot | Straight edge, no piercing point, so there is less risk of stabbing yourself (AKTI) | Not for poking holes or opening knockout boxes |
| Coping / pointed | Thin point for stripping wire and opening boxes (AKTI) | The point is the part that slips and punctures inner insulation (our view) |
| Cable splicer's knife (Klein 44200 type) | Klein lists its 46037 kit, which includes the 44200, for cutting cable and stripping insulation | Klein warns it is not insulated |
| Insulated (VDE) cable knife | Built to IEC 60900 for live work up to 1000 V AC / 1500 V DC; each tool is tested at 10 kV (Boddingtons) | Short blade (a Knipex example has a 50 mm blade, RS Components) |
AKTI's safety points apply to every type: prefer a locking folder so the blade cannot close on your fingers, keep the edge sharp, and use a knife with a finger guard. Australia's Safety Solutions adds: de-energize first, take care not to damage the conductor when stripping, and avoid snap-off blades, which can snap and injure your hand.
The Japanese denko knife (電工ナイフ)
In Japan the electrician's knife is called a denko knife (電工ナイフ, "electrical-work knife"). It is on the designated tool list for the second-class electrician practical exam alongside pliers, screwdrivers, a scale, water pump pliers and a ring-sleeve crimper (U-CAN, Agaroot), and Panasonic's exam tool guide and Agaroot both advise against using a box cutter in its place. Aomori Prefecture's skills course requires trainees to bring one.
What makes it different, from Japanese exam publishers and guides:
- It is used to strip VVF/VVR cable sheath (Mynavi) and, more generally, for wire processing (Gihyo). VVF is Japan's flat, PVC-sheathed house cable; in our view it is close in use to NM cable.
- The blade is thicker than a utility knife blade, which Mynavi says helps avoid cutting too deep.
- You cut with the middle-to-heel part of the blade, not the tip, and some electricians keep the edge slightly dull so it does not nick the copper (Gihyo, an exam-book publisher).
- Not all denko knives are insulated, so using one on live parts risks shock (Gihyo).
What "hollow ground" means on the job
All three knives below are listed with a hollow-ground blade (TSUNODA; TAJIMA Taiwan; Tool Nut; datemono). A hollow grind is a concave scoop ground into both sides, leaving a thin edge. AG Russell calls it one of the best grinds for slicing, says it is weaker under hard use, and notes that the edge stays nearly as thin as new after resharpening. In our view, on a cable jacket that means the edge slices PVC cleanly when you draw it, but it is the wrong blade for prying staples or scraping paint.
How to strip a cable jacket with a knife
The steps combine the Japanese exam guidance above with the safety points from AKTI and Safety Solutions; where a step is our own practice, it says so.
- Turn the circuit off (Safety Solutions) and verify it is dead with a tester (our practice; see our non-contact voltage tester guide).
- Lock the blade open (AKTI) and hold the cable on a firm surface or across your finger, never in your palm under the blade (our practice).
- Score around the jacket lightly at the strip length, using the middle-to-heel of the blade (Gihyo; the scoring technique is our practice). On flat VVF/NM you can score only the two flat faces and bend to snap the jacket (our practice).
- Slit lengthwise toward the end and away from your body, keeping the blade shallow so it rides on the jacket and does not reach the conductor insulation. A hawkbill's curve helps keep the cable from slipping off the blade (AKTI).
- Peel the jacket off and inspect the inner insulation. If you see a nick, cut the cable back and start again (our practice; Safety Solutions warns against damaging the conductor).
- Strip the individual conductors with a stripper, not the knife, when you need an exact length (our practice; see best wire strippers).
Japanese electrician's knives and scissors compared
Specs come from the maker's page where it lists them, otherwise from two Japanese retailers; where sources disagree we write Not confirmed. One column is calculated by us:
- Blade share of open length = blade length ÷ overall length × 100. A higher share means more of the tool you are holding is cutting edge; a lower share means more handle (or wrench) behind the blade.
| Model | Type | Overall length | Blade length | Blade share | Weight | Notable | Origin |
|---|---|---|---|---|---|---|---|
| TSUNODA EK-72 (電工セーフティナイフ) | Folding | 177 mm | 72 mm | 41% | 107 g | Hollow blade; lock (TSUNODA lists a back-lock mechanism); stainless steel with natural-wood handle; strap hole for a safety cord (TSUNODA shop) | Japan (our product page; Not confirmed on TSUNODA's page) |
| TAJIMA DK-FKMU (折込電工ナイフ マルチ) | Folding + box wrench | 198 mm (MonotaRO) | 68 mm | 34% | Not confirmed | SK-5 blade (TAJIMA Taiwan); 17 × 21 mm wrench for temporary tightening; lock (datemono); hollow-ground sheepsfoot blade, hard chrome plated (Tool Nut) | Not confirmed |
| TAJIMA DK-TN80 (タタックナイフ) | Fixed, through-tang | approx. 234 mm (MonotaRO; SFS lists 235 mm) | Not confirmed (sources list 70, 89 or 90 mm) | — | Not confirmed (130 g or 167 g) | Hollow blade for splitting VVF sheath, deburring groove on the spine, can be struck with a hammer, chrome plated, polycarbonate sheath (TAJIMA Taiwan); end cap so your hand does not touch the metal directly (MonotaRO) | Not confirmed |
| FUJIYA FM04-180NL-BG (電工ストレートバサミ) | Electrician's scissors | 188 mm | — | — | 107 g | Cuts VVF 2.0 mm × 3-core and soft resin to φ20 mm; thumb-operated lock; long straight blade for stripping sheath (MonotaRO, ems-tools) | Taiwan (ems-tools) |
Reading the table: the EK-72 and DK-FKMU have almost the same blade (72 vs 68 mm), but the DK-FKMU is 21 mm longer overall because the wrench sits behind the blade, so its blade share drops from 41% to 34%. If you want the smallest thing in a pocket, that difference matters; if you are tightening 17 mm or 21 mm hex fittings on the same job, it is the point of the tool. The DK-TN80 is the only one built to be hit with a hammer, which is why it is a fixed through-tang knife rather than a folder.
What to check before buying: none of these four is sold as an insulated IEC 60900 tool, so none is for live work. We do not claim one steel cuts longer than another; we have not found a test that compares them.
Which one for which job
Residential and light commercial: NM/VVF jacket stripping (our grouping)
- TSUNODA EK-72: in our view the classic Japanese denko knife shape. Hollow 72 mm blade, lock, 107 g, and a strap hole for a safety cord (TSUNODA shop).
- FUJIYA FM04-180NL-BG: if you would rather not carry an open blade, electrician's scissors cut 3-core VVF and peel sheath with a long straight blade (MonotaRO).
Panel, trunking and fittings work (our grouping)
- TAJIMA DK-FKMU: knife and a 17 × 21 mm box wrench in one folding tool; in our view it suits jobs where you open cable and snug a nut in the same few minutes.
Heavy cable, demolition and old installations (our grouping)
- TAJIMA DK-TN80: a fixed through-tang blade with a striking cap and a deburring groove; TAJIMA describes it as a multi-purpose knife for electricians that can be hit.
FAQ: questions electricians actually ask
Hook knife or cable splicer's knife for NM cable?
Both, depending on who you ask. In a Mike Holt Forum thread started by an electrician who lost his Klein knife for NM cable, one reply described using a folding hook knife and then cutting the slit sheath off with cutters, another preferred the cable splicer's knife, and a third used a razor knife and said he had learned its sound and feel. On BladeForums, a former electrician called a Klein hawkbill ideal for slitting old Romex. In our view a Japanese denko knife sits between the two: a straight blade that you draw rather than hook, cutting with the middle-to-heel part of the edge as Gihyo advises.
Can I just use a utility knife?
Many electricians do; a residential worker in the NYC/Long Island area on BladeForums said a cheap utility knife works best for him, and on Talk Electrician UK one member said he mostly uses a Stanley. But a UK student starting college said in that thread that his college does not allow Stanley knives, and Japanese exam guides advise against a box cutter in place of a denko knife (Panasonic, Agaroot). Mynavi's reason: a denko knife's thicker blade is less likely to cut too deep.
Is a knife safer than a stripping tool?
Not necessarily. On Talk Electrician UK, one member said he stopped using knives after a near-miss and now uses stripping tools. If most of your work is the same cable size, a VVF/cable stripper removes the jacket without an open blade; a knife stays useful for odd sizes, old cable and boxes.
Are these knives insulated for live work?
No. Klein warns that its cable splicer's knife is not insulated, Gihyo notes that not all denko knives are insulated, and none of the four tools above is sold as an IEC 60900 insulated tool. Insulated tools carry the double-triangle symbol and "1000V" marking (Boddingtons). Turn the circuit off.
Does the TSUNODA EK-72 have a single or double bevel?
Not confirmed. TSUNODA lists a hollow-shaped blade but does not state the bevel.
Related guides
- Best Wire Strippers for Your Wire: AWG Sizes, Automatic vs Manual
- Best Cable Cutter for Your Cable Size
- Best Wire Cutters by Job
- Best Lineman's Pliers by Job
- Best Non-Contact Voltage Tester
- Japanese Electrician Tools: 8 Brands to Know
- Japanese electrician knives and scissors
Find your electrician's knife
Denko knives, electrician's scissors and cable strippers from TSUNODA, TAJIMA and FUJIYA, inspected and shipped from Japan.
Shop electrician knives and scissorsSources
- American Knife & Tool Institute, Electricians: what you need to know about knives
- Electrical Contractor magazine, Knives for electricians
- Klein Tools 46037 kit (cable splicer's knife 44200)
- Safety Solutions, Knife safety: an electrician's guide
- Boddingtons Electrical, Understanding insulating tools to IEC EN 60900
- RS Components, Knipex 1000 V cable knife
- AG Russell, Blade grinds
- TSUNODA, EK-72 product page and TSUNODA shop, EK-72
- TAJIMA Taiwan, DK-FKMU and DK-TN80; TAJIMA Japan, DK-TN80
- MonotaRO product pages: DK-FKMU, DK-TN80, FM04-180NL-BG; datemono (DK-FKMU); SFS (DK-TN80); ems-tools (FM04-180NL-BG); Tool Nut (DK-FKMU)
- Panasonic, tools for the second-class electrician exam (PDF, Japanese)
- U-CAN, second-class electrician designated tools (Japanese) and Agaroot (Japanese)
- Aomori Prefecture skills course notice (PDF, Japanese)
- Gihyo, electrician's tools sample chapter (PDF, Japanese) and Mynavi, denko knife guide (Japanese)
- Mike Holt Forum, Klein BM cable knife; Talk Electrician UK, Electrician knife; BladeForums, Electricians knife
Last reviewed: October 2026. Not affiliated with TSUNODA, TAJIMA, FUJIYA, Klein Tools, Knipex or AKTI.
