Cable Knife buying criteria: These are the 5 features you should pay attention to
But not all cable knives are created equal: cable diameter, insulation material, application, and safety requirements vary. Consequently, the demands placed on the tool also differ. Therefore, anyone looking to buy a cable knife should pay particular attention to five features: blade quality, cutting depth adjustment, ergonomics, safety features, and the appropriate application.
Why the quality of a Cable Knife is crucial
On construction sites and during electrical installations, cable stripping is a daily task. Cable knives are therefore frequently used. A high-quality tool should function precisely and reliably over the long term, allowing for controlled cutting.
The following are particularly important:
- Precision: The cable sheath should be cleanly cut and removed.
- Protection of inner conductors: An appropriate cutting depth reduces the risk of damaging underlying conductors and their insulation.
- Ergonomics: A well-designed tool supports controlled and effortless work.
- Safety: Designed safety mechanisms significantly reduce the risk of cuts.
- Durability: High-quality, replaceable blades extend the tool's lifespan.
You can find even more information on working with cables and wires, as well as the correct use of various tools, in the JOKARI Wire Stripping FAQ.
What should you look out for when buying a Cable Knife?
1. High-quality blades ensure clean cuts
The blade is the heart of a cable knife. It must be sharp enough to cut through various cable sheaths in a controlled manner. At the same time, it should retain its cutting performance for as long as possible, even with regular use.
A high-quality blade enables precise circular and longitudinal cuts, reduces messy or frayed edges, and minimizes the effort required. Therefore, when purchasing a cable knife, it's worth paying attention to the following points:
- High-quality, durable blade steel
- Sharp and long-lasting cutting edges
- Precise circular and longitudinal cuts
- Cleanest possible cut edges
- Replaceable blades
- Good availability of spare parts
2. The correct cutting depth setting protects the inner conductors
When stripping cable sheaths, the blade should cut the outer sheath in a controlled manner without damaging the underlying components. This is precisely why the cutting depth adjustment of a cable knife is an important purchasing criterion.
Cables and wires differ not only in diameter but also in construction, material, and sheath thickness. An adjustable cutting depth allows the tool to be adapted to these differences.
This offers several advantages:
- Individual adjustment to different sheath thicknesses
- Controlled cut
- Reduced risk of damaging the inner conductors
- Clean circular and longitudinal cuts
- Increased process and workplace safety
On classic JOKARI Cable Knives, the cutting depth is adjusted via a screw. Correct adjustment is crucial: The insulation should be cut in such a way that it can then be removed cleanly without endangering the underlying components.
3. Ergonomic handle for comfortable working
Someone who only makes a single cut probably doesn't think about ergonomics. However, anyone who works with cables day in and day out quickly realizes the difference a well-designed tool makes.
An ergonomic cable knife should fit securely and comfortably in the hand. Non-slip or grippy components and a shape adapted to hand movements can help guide the tool precisely and use your hand strength effectively.
Therefore, pay attention to:
- secure grip
- grippy surfaces
- ergonomic tool shape
- controlled guidance
- effortless handling
- good usability according to the intended work situation and personal protective equipment
Ergonomics pays off especially with repetitive wire stripping tasks: less unnecessary effort means more comfortable and controlled work.
4. Safety features reduce the risk of injury
Safety should be your top priority when buying a cable knife. Cable knives operate with very sharp blades. This makes them efficient, but also poses a risk of injury if handled incorrectly or if the tool is poorly designed.
A simple utility knife or carpet knife is therefore not a suitable substitute for a proper wire stripper. Such universal knives lack the guide specifically designed for cable work. This can increase the risk of both injuries and damage to the internal conductors.
When purchasing a cable knife, you should check, among other things, whether the tool offers safety features, such as:
- protected or guided blades
- protective mechanisms against accidental contact with the cutting edge
- secure locking mechanisms
- controlled tool guidance on the cable
- adjustable cutting depth
- ergonomic and secure grip areas
- independent safety testing, if applicable
5. Durability thanks to replaceable blades
JOKARI embodies true toolmaking tradition: The classic JOKARI Cable Knives are equipped with high-quality steel blades from Solingen. Furthermore, a spare blade is already integrated into the JOKARI cable knife. If the inserted blade becomes worn, it can be replaced instead of having to replace the entire tool.
We show you how to easily change the blade on a Cable Knife step by step, including FAQs and application instructions, or in this video:
Practical tip: A dull blade should not be "compensated for" by applying more force. If the required force increases significantly or the cutting quality deteriorates, the blade should be checked and replaced if necessary.
Practical example regarding safety: The JOKARI Cable Knife System 4-70
The JOKARI Cable Knife System 4-70 (Art no. 70000) demonstrates how safety can be integrated into the design of a Cable Knife.
The tool features a patented safety mechanism for the hook blade with a locking switch, designed to prevent cuts. A viewing window in the interchangeable handle allows for monitoring the cutting process. The cutting depth of the inner blade can be adjusted via a screw; the penetration depth of the hook blade can be regulated in four stages.
Additional safety and comfort features include:
- Safety mechanism for the hook blade with locking switch
- Controlled guidance of the tool along the cable
- Viewing window for monitoring the cutting process
- Adjustable cutting depth
- Four-stage adjustable penetration depth of the hook blade
- Soft grip zones for controlled handling
- TÜV/GS certified
The System 4-70 thus combines several of the criteria that are relevant when selecting a safety cable knife.
Safety begins before the first cut
Even the best safety design cannot completely compensate for incorrect use. Therefore, before working, users should check:
- Is the tool suitable for the cable type and diameter?
- Is the blade sharp, undamaged, and correctly inserted?
- Is the cutting depth set correctly?
- Are all existing safety guards and locking mechanisms functioning properly?
- Is a de-energized and safe working condition established in accordance with the applicable electrical regulations?
A good cable knife offers protection on two levels: It helps protect the user from cuts while simultaneously enabling controlled cutting to minimize damage to the individual conductors inside.
The cable knife must fit the application
When selecting a Cable Knife, it's crucial that the tool is compatible with the cable being cut. Before purchasing, you should therefore answer the following questions:
- What is the cable diameter?
- Will you primarily be working with round cables?
- Are they, for example, NYM, NYY, or other cable types?
- What is the thickness and material of the outer sheath?
- Will you be cutting larger cable diameters?
- Will you frequently be working in tight junction boxes or other hard-to-reach areas?
- Is a special tool required for a specific cable?
The JOKARI Cable Knife System 4-70, for example, is designed as standard for common round cables with diameters from 8 to 35 mm and is suitable for cables such as NYM-J, NYY-J, and NHXMH-J. The System 4-70 Set extends the range to 4 to 70 mm in diameter.
However, a cable knife isn't the ideal solution for every application. In tight electrical boxes, for example, a compact cable stripper might be more practical, while for single wires, wire strippers are often the better choice. Special cables, on the other hand, may require specially designed tools.
We explain the differences between cable knives, cable strippers, and wire strippers in detail in the JO!STORY article "Different Stripping Tools in Electrical Installations: What's the Difference?".
Our current guide “The 10 best wire stripping tools 2026: Which tool for which application?” offers further guidance.
Conclusion: Quality pays off when it comes to Cable Knives
A good cable knife needs to do more than just cut. High-quality blades, precise cutting depth adjustment, ergonomic handling, and well-designed safety features make a crucial difference in everyday cable work.
Choosing the right tool is equally important. Round cables, NYM and NYY cables, large cable diameters, and work in confined installation spaces all place different demands on stripping and sheathing.
Paying attention to quality, safety, and the intended application when purchasing a cable knife lays the foundation for clean results and a long tool life.
Want to learn more about cable work, stripping, and choosing the right tool? Discover more practical tips, instructions, and tool knowledge on the JO!STORY blog!