Hey everyone, and welcome back to the blog—today we’re diving into a question we get all the time here at the shop (and yeah, I’ve lost count of how many times our guys on the support line repeat this): “What’s the breaking load of an installation cable, anyway?” Installation Cable
If you’re new to working with cables—whether you’re an electrician on a residential job, a contractor running power for a retail fit-out, or even someone just trying to wrap your head behind the specs on that spool you bought last month—this term might sound like just another tech-jargon line on a data sheet. But trust me, it’s way more important than it sounds. Skimping on paying attention to breaking load? That’s how cables snap mid-install, how jobs get delayed, and (worse) how people end up dealing with dangerous, avoidable messes.
Let’s start with the basics: what actually is breaking load? For anyone who’s ever torn a plastic bag a little too hard, or stretched a rubber band until it pinged across the room, this is exactly the same concept—just for heavy-duty cables that hold up power, data, or control signals in buildings, warehouses, and even outdoor setups. Breaking load (sometimes called “tensile breaking strength” if you’re reading the fine print) is the maximum amount of pulling force a cable can handle before it splits, frays, or breaks entirely. And no, it’s not a random number—every installation cable is engineered with this specific spec tailored to what it’s going to do.
Wait, hold on—before you go “cool, so it’s just how hard you can pull it?” here’s the catch: not all cables are built the same. A 14/2 Romex for a bedroom wall? Its breaking load is way lower than a 4/0 power cable you’re pulling through 100 feet of conduit in an industrial basement. That’s because each installation scenario has different pull forces. Let’s break down why that matters. When you’re running a cable, you’re not just tugging on the end gently—you’re pulling it through conduits, around corners, over bends, sometimes even around structural beams. All that adds up to pulling force on the cable’s core. If your cable’s breaking load is too low for that job? You’ll hit a point where the insulation tears, the copper conductor snaps, or the armor (for armored cables) cracks.
Here’s a real example from a job we did last quarter: a small electrical contractor came to us panicking because they’d bought some cheap 10mm² installation cable from a no-name supplier. They were pulling it through a 90-degree bend in a 2-inch conduit, and halfway through, the cable snapped—right when they were 70% done with the install. Turns out, that cheap cable had a breaking load of only around 1,200 Newtons (N), but the actual pull force they needed was closer to 2,100 N. We swapped them over to our standard industrial-grade installation cable, which hits 2,500 N breaking load, and they finished the job in an hour instead of losing a whole day running back to supply stores and fixing the mess. That’s the difference between knowing your breaking load and guessing.
Now, how is breaking load calculated? It’s not just a guess from the factory—there are standardized tests for this. Most installation cables follow IEC standards (IEC 60227 for fixed power cables, IEC 60332 for flame tests, but breaking load is usually covered in IEC 60942 for flexible cables, if I’m not mixing up my specs). The test is pretty straightforward: you clamp one end of the cable tight, hook the other end to a tensile tester, and slowly pull until the cable breaks. The number on the tester right when it snaps is the breaking load. But here’s the thing: that number is also adjusted for the cable’s construction. If you have a cable with a steel armor layer (like our AC90 armored installation cable), that armor adds a ton to the breaking load—so it’s not just the copper or aluminum conductor holding up. For unarmored cables, the breaking load comes from the conductor (copper or aluminum), the insulation, and any reinforcing materials woven into the jacket.
Wait, but let’s talk about a related term people mix up all the time: working load vs breaking load. Super important to not confuse these! Working load (or safe working load, SWL) is the amount of force you should apply to the cable during installation. That’s never the full breaking load. For most of our installation cables, the safe working load is about 50-60% of the breaking load. So if a cable has a 2,500 N breaking load, you never want to pull it harder than 1,250-1,500 N. Why? Because even if you can pull it to 2,500 N without breaking it, pulling that close weakens the cable over time—you might not see a break during install, but months later, that stress will cause a fault. For outdoor installation cables, that margin is even wider (sometimes 40% of breaking load) because they have to handle wind, snow, or even accidental tugs from equipment later.
Now, let’s get into what factors affect a cable’s breaking load, because it’s not just one spec. First, conductor material: copper has a higher tensile strength than aluminum, so a copper cable of the same size will have a higher breaking load than an aluminum one. That’s why copper is often the go-to for long pulls—you don’t have to worry about it snapping mid-job. Then, conductor size: thicker conductors (like 4/0, which is 107mm²) have more copper, so way higher breaking load than a 14AWG (2.08mm²) wire. That makes sense, right? More metal = stronger.
Next, cable construction. Armored cables (with steel or aluminum armor sheathing) have a massive boost in breaking load—some of our armored installation cables hit 10,000 N breaking load, perfect for pulls through tight conduits or outdoor runs where you might have to drag the cable a little over rough ground. Even unarmored cables have reinforcing: for example, our LS0H (low smoke zero halogen) installation cables have a polyester core woven in around the conductor, which adds extra tensile strength without making the cable stiff. Jacket material also plays a role: a PVC jacket is tough, but a cross-linked polyethylene (XLPE) jacket is even stronger, so XLPE-jacketed cables will have a higher breaking load than PVC of the same size.
Then there’s the installation method. Wait, that’s a factor? Yeah! If you’re pulling a cable straight through a smooth conduit, your pull force is lower. But if you’re pulling around multiple 90-degree bends, that friction adds up. If you’re running cable over a beam or a ledge, that creates a sharp point that can pinch the cable, reducing its effective breaking load by 20-30% right there. We always tell customers: when calculating your required breaking load, add a 15-20% safety margin for those curve and friction factors. Because even if your cable’s spec is 2,500 N, if you’ve got three bends, that’s 2,125 N total—so you need a cable with at least 2,200 N breaking load, minimum.
Let’s talk about common mistakes we see people make with breaking load. The biggest one is ignoring the spec on cheap cables. We’ve had customers come in with cables that say “10mm² power cable” on the spool, but when we look at the data sheet, their breaking load is 800 N—way too low for a long pull. Another mistake is mixing up cable types: using a data cable’s breaking load for a power cable? Data cables have way lower tensile strength, so they’ll snap if you pull them hard for power runs. And don’t forget outdoor vs indoor: indoor installation cables are often thinner, with less reinforcement, so their breaking load is lower. If you run an indoor cable outside, where you might have to drag it over dirt or through overhead branches, you’re way more likely to break it.
Wait, what about termination? That’s another hidden factor. Even if your cable has a high breaking load, if you crimp a terminal wrong, the terminal will pull out of the cable before the cable itself breaks. So when you’re installing, make sure your crimps are done properly—use a hydraulic crimper for heavy cables, not pliers, because pliers don’t create a tight enough connection. That way, you’re actually using the cable’s full breaking load, not wasting it on a bad termination.
Now, let’s tie this back to why this matters for you, if you’re working with installation cables. If you’re a contractor, getting the right breaking load means no more wasted time re-running cables, no more extra costs for replacement materials, and most importantly, no safety hazards. If you’re a DIYer doing a home reno? Skip the cheap big-box store cables—they often cut corners on breaking load to save money. That $20 spool might look like a deal, but if it snaps while you’re running power to your new workshop, you’re looking at $100+ in extra work and a huge headache.
At our company, we test every spool of installation cable that leaves our warehouse for breaking load. We don’t just rely on factory specs—we do random tensile tests every week to make sure what’s on the data sheet matches what’s in the box. That’s why our customers come back: they know when they pull our cable, it’s going to hold up. We even give each customer a free pull force calculator sheet when they order, so they can figure out exactly what breaking load they need for their specific job.
So, to wrap this up: breaking load is the max pulling force an installation cable can take before breaking. It’s not just a tech spec—it’s the difference between a job that goes smooth and one that derails. Always remember to use safe working load (not full breaking load), add a 15-20% margin for installation friction, and pick a cable whose breaking load matches your project’s needs.
If you’re planning an installation, whether it’s a small residential job or a big industrial build, and you’re not sure what breaking load you need for your cable, hit us up. We’re here to help you pick the right cable, no jargon, no pressure. Just shoot us a message and we can walk through your project step by step.
High Voltage Power Cable References:
IEC 60227: Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V
IEC 60942: Flexible cables for installation purposes – Requirements and test methods
National Electrical Code (NEC) Article 334: Fixed branch circuit wiring (non-metallic sheathed cable)
Jiangsu Changcheng Cable Co., Ltd.
Jiangsu Changcheng Cable Co., Ltd. is one of the most professional installation cable manufacturers and suppliers in China for over 25 years, providing the best customized service with low price. Please feel free to wholesale cheap installation cable from our factory.
Address: Room 2101, Yunhe Building, No.318, West Wenchang Road, Yangzhou City, Jiangsu Province, China
E-mail: info@cncablefactory.com
WebSite: https://www.cncablefactory.com/
