Insulated pliers are very important for working around live or de-energized circuits and equipment. They protect you from electrical shock from dangerous voltages up to 1000V AC and 1500V DC. But how do you tell that your pliers are insulated and thus safe for use in a live circuit? And, are all rubber handle pliers insulated?
Well, in this article, you will learn how to tell if pliers are insulated, the voltage range for which you can use them safely, and how to tell when the insulation is compromised.
What are insulated pliers?
Insulated pliers are not your ordinary pliers with thick plastic or rubber material on the handles. No, they are pliers with dielectric material on the handles for protecting you from electrical shock.
Unlike regular pliers, the electrical properties of the dielectric material on insulated pliers are known. This is what makes the difference between insulated pliers and ordinary rubber handle pliers or plastic dipped pliers.
Therefore, even though some regular pliers may provide some insulation from electrical shock, you cannot tell their threshold voltage. Also, there is not indication that they have been tested for safety. This is what makes them unsafe for use on live circuits and equipment.
On the other hand, insulated pliers go through a series of tests including electrical stress test to determine the maximum voltage above which they stop being insulative. The threshold voltage, also known as dielectric breakdown voltage is then stamped on the handles.
When you expose the pliers to a voltage above the electrical breakdown voltage, the insulation material may become conductive and can become a hazard. So, always make sure you use the pliers within the prescribed voltage range. Typically, insulated pliers are rated 1000V AC and 1500V DC, unless otherwise.
But besides checking the maximum voltage marking on the handles, how else can you tell that pliers are insulated?
How to tell if pliers are insulated
There are many ways to tell if pliers are insulated. You can either inspect them visually or perform some electrical or physical tests.
You can make a couple of visual observations on pliers to tell if they are designed for use in an electrified environment. They include reading the stamped voltage rating and certifications, observing the design of the handles, and checking the integrity of the insulation material.
Maximum voltage rating
As mentioned above, the first observation you can make is to read out the voltage value stamped on the handles. This is the dielectric voltage or the breakdown voltage rating. It is the voltage above which insulated pliers lose their insulation property. Typically, most insulated pliers are rated 1000V AC and 1500V DC.
Quality assurance markings
Besides the breakdown voltage, other things you will see stamped on the handles of insulated pliers are various markings for the quality assurance tests the pliers have passed. Typically, you will see stamps such as VDE, GS, UL, IEC 60900, and ASTM F1505.
For instance, VDE and GS are European marks of safety for electro-technical products. On the other hand, the UL marking shows that a product has undergone all applicable tests. IEC 60900 is the international standard for insulating tools for working in live or close to live parts of nominal voltages of 1000V AC or 1500V DC.
Another way to easily tell that pliers are insulated is to look at the handles. Although insulated pliers have chunky handles just like regular pliers with comfort grip handles, they have larger handle guards. The guards protect your hand from slipping to the metallic part.
So, even though rubber handle pliers may have guard rails on the handles, the rails are significantly smaller than those of insulated pliers.
Color coded insulation material
Another notable difference between insulated pliers and regular pliers is the double layer color-coded handle grips. The handles of insulated pliers are dual-layered and each layer has a different color. Typically, the upper layer is red or orange and the inner layer is yellow or white but you can find other colors too. For example, Klein insulated pliers have orange and black layers.
Besides adding to the thickness of the handles, the inner insulation layer acts as a warning to tell you when the insulation is compromised. So, if the handles of insulated pliers are damaged such that the inner layer is exposed, those pliers are not safe anymore. You cannot use them around live lines or equipment.
No spring mechanism
When buying pliers, most people prefer those with a spring mechanism because they minimize hand fatigue. The spring keeps the jaws open so that you don’t have to manually push the handles to open the jaws. This is different for insulated pliers.
Insulated pliers are hardly spring loaded. And those that have a spring mechanism, it is a plastic spring. The reason for this is to avoid the dangers that may occur if a spring-loaded pliers breaks down and the metallic spring falls into the live parts of an equipment and shorts things up causing problems.
Another reason why insulated pliers are typically not spring loaded is to keep the jaws from potentially shorting things up. This can happen when working in a tight space on a live equipment.
Electrical Inspection of insulated pliers
Other than the visual properties that are easy to spot off the bat, insulated pliers have unique electrical properties. So, you may want to take your inspection further to perform an electrical test on the handles to determine the actual dielectric breakdown voltage. This might be helpful when working on circuits that are capable of having higher voltage spikes than the pliers rating.
Sometimes the urge to do an electrical test on insulated pliers may just be out of curiosity. You know some manufacturers claim that their insulated pliers exceed specific electrical standards and you may be tempted to test the claim. This is the test you would perform.
Insulation Resistance Test
The electrical test you can perform on the handles is known as the insulation resistance test. You use a device called an insulation tester or megometer. The device measures high resistance values by sending a high dc voltage signal into an object.
So, to measure the resistance of the handle insulation material, you connect one of the leads to the jaw and the other to the insulation. Then inject a DC voltage through the jaw (start with 500V DC) and the test leads will measure the resulting resistance.
If the pliers are safe, you should read a very high resistance value in the range of 1000s of megaohms. However, as you increase the test voltage, you may notice the insulation resistance value decreasing. This means that insulated pliers become less safe as the voltage increases above the threshold or breakdown voltage.
You can also perform physical tests on insulated pliers to find out if they are what the manufacturer claims. Unfortunately, most physical tests are destructive and I don’t think you want to destroy your new pliers. But if you are just curious, there is no harm in performing the experiment.
One of the tests you can perform is the flame resistance test. Most insulated pliers are marketed as flame retardant, meaning that they stop burning immediately after you withdraw the flame.
Well, those are some of the key properties of insulated pliers that set them apart from other regular pliers. In a nutshell, insulated pliers have dual layer handle grips, maximum voltage is stamped on the handles, the double layers have different colors, and the handles have large guard rails.
Frequently Asked Questions
Two main reasons why insulated pliers have double layer are to increase the thickness of the handles and to make it easier to spot when the insulation is damaged. For example, if the handles of your insulated pliers are damaged such that you can see the inner layer, those pliers are dangerous and you should not use them around a live circuit or equipment.
No. It is against OSHA regulations (OSHA 1910.333)to work on energized or live parts when you can de-energize them. So, you should always de-energize live parts before working on them unless turning off the electricity is totally infeasible. Insulated pliers are only meant to protect you from electric shock when you accidentally encounter a live part.