Mueller Electric Blog

How to Select the Right Electrical Clip

Posted by Mona Weiss on Apr 11, 2018 8:23:21 AM

From electrical design to maintenance, engineers must determine what electrical clips (also called alligator or crocodile clips) are best suited for their project.

These clips can range from small to large, be made of a wide range of materials, come in various jaw types, handle wide ranges of electrical current and can be certified for safety by being UL-listed.

With such a wide range of options, there are many factors to come into play when selecting clips


Typically, electrical and electronic clips are rated by their ability to handle varying levels of current which is measured in amps so you will need to know the amount of current that you will be dealing with.

Once you know the level of current, you can calculate the amperage rating required for the clip.

The formula for Amps is Watts divided by Volts.

The amperage capacity of a clip is typically listed right on the clip itself.

Generally speaking, larger clips are able to handle more current, however, that doesn’t always mean a larger clip is always necessary. Solid copper clips are able to handle higher levels of current and carry a higher amperage rating than its zinc plated steel counterpart. For example, a heavy duty clip for battery and test work applications may be rated at 50 AMPS for the zinc-plated steel version while the same sized clip made in solid copper is rated at 100 AMPS. 



Clip Jaw Typesclip jaws4

Another factor to be considered is how the clip needs to connect to its point of contact. Clips come in all shapes and sizes with different types of jaws and teeth. Clip jaws can come flat nosed, with teeth, or wrap around a terminal or pipe. Some clips have flat wide noses with teeth and others may be rounded to grab round objects. Deciding which clip to use is dependent of what the clip is grabbing on to and will vary per application.

Flat nosed clips are typically used in paint grounding.

Smaller clips with teeth are used for test and measurement.

Larger clips that wrap around will provide a strong grip and may penetrate a layer of paint. These are often used for battery charging and grounding.

Flat wide jaws with teeth are perfect for grounding and work holding uses.

There are, however, a tremendous number of applications for all types of jaw styles. As technology progresses, so do clips, with new types being invented all the time.

For more on different types of clips and what they are used for, check out our guide to clips

Clamp Pressure

Clip grabbing strength, or clamp pressure, is another factor to take into consideration when selecting the right clip. Clamp pressure usually increases as clip and spring size increase. Larger clips will have a stronger grip than smaller clips. In some cases clips can be made to have less clamp pressure which can be helpful for delicate or detailed situations.

Clip Size

There are many different sizes of clips and size can sometimes be important to consider. One determining factor is if there is a space requirement. Another factor is the amount of clamp pressure required, as well as the amperage rating needed.

Some clip sizes are determined by the application itself as there may be limited space where the clip can fit.  Naturally if you have a small space then you probably will pick a smaller clip.

Higher amp rated clips tend to lend themselves to uses where a tight space is not a concern. The environment may dictate what a clip size may need to be as the larger clips tend to hold up better in harsh environments such as electroplating.

There is no real guideline on determining what clip size to use. Some engineers try to make sure they have the right amperage rating, clamp pressure and jaw type in the smallest package possible to reduce the possibility of “overkill” and inflating costs unnecessarily. Other engineers go one step up in size to ensure all bases are covered. In most cases, several different sizes of clips are used in various prototypes to test first hand which clip size is best.


3 alligator clips rectangle-1

Clips are made with zinc or nickel plated steel, stainless steel, solid copper, gold plating and even nickel-silver.

Generally speaking, zinc or nickel plated steel is the most cost effective material used in clips.

Solid copper clips can handle higher levels of current better than similarly sized clips made of other materials.

The environment where the clip will be used can determine what material should be used for a clip. For example, stainless steel clips can withstand marine, caustic or corrosive environment better than other materials. Other clips that can be used in marine environments are marine rated clips which are made of solid copper for greater connectivity but with moisture resistant springs which significantly extend the life of a clip used in the vicinity of water and salt.

We did an experiment to show how marine and stainless steel clips hold up compared to other clips. Read about it here. 

Read about different metal finishes for clips here.  


Safety is always a consideration when working with electrical components, but some more than others.

For instance, when using clips and cables for grounding and bonding, an exposed clip works just fine, while other applications it may call for an insulated clip.

UL Listed products are certified for safety. UL Listed clips and connectors are certified to insure that human hands cannot come in contact with the conductors while in use and energized.

Other applications may call for clips to be utilized in a “hands free” environment which means that the clips are not manipulated or touched while a circuit is energized. The clips still need protection from touching each other or other parts which could interfere with the electrical signal or cause a short, so insulators or “boots” are placed over the clips to protect them.

For help in selecting clips with different features, try our clip selector.

Topics: Test & Measurement, Static Electricity Grounding, Grounding, electronics, crocodile clip, engineering, alligator clip, Marine Clips

Underwriter Laboratories (UL) Listed Items

Posted by Mona Weiss on Mar 20, 2018 2:00:00 PM

Underwriter Laboratories has set the standards for product safety and has a through certification process. Mueller Electric is proud to provide UL Listed items and this blog post will provide some insight into what it means for something to be UL listed.

Underwriter Laboratories (UL) is the best known, largest and oldest independent testing laboratory in the United States and a world leader in product safety testing and certification. They set safety standards for different product categories and test products to make sure they meet those standards.

UL tests over 19,000 different products annually, ranging from consumer electronics, alarms and security equipment, to lasers, medical devices and robotics. 

There are two types of UL products that Mueller has. One is a listed product that is sold to an end consumer, and the other is a UL listed component that is meant to be used as part of other UL listed products.

UL Clip BU-60

A product that is UL listed has been thoroughly tested for safety and sometimes includes features that make it safer than similar products. For example, the Mueller BU-65 alligator clip is fully insulated and includes a guard near the teeth to prevent fingers from accidentally touching the teeth and has a fully shrouded connection. 



Mueller’s UL listed test probes and banana connecters also have a finger guards for safety, while the BU-6161-M-@ test lead has shrouded banana plugs at each end. These fully shrouded plugs ensure there is no exposed metal.


UL inspects Mueller's facilities on a quarterly basis to ensure the products continue to be manufactured to the high safety standards that they were originally reviewed under. 


Check out our high voltage test & measurement page.

For a general overview of clips, check out our guide to clips.

 Learn more about banana connectors here

Topics: Test & Measurement, engineering, alligator clip, wires

Painting Plastics: How to Produce High-Quality Output in a Low Cost Environment

Posted by Tim Ulshafer on Jan 25, 2017 1:03:11 PM

With the vast varieties of paint, materials and application processes, the achievement of an efficient, high-quality and consistent automated painting process can often seem elusive. How can the director of the painting operation optimize output and quality while controlling costs?  Output is useless without quality.  The cost of scrap and rework adds up quickly, and can delay the overall project. For example, if a painted plastic bumper cover has flaws and needs to be reworked or scrapped, then that component will not be available for assembly to the designated automobile, potentially impacting the production line or the customer (and who wants rework stacking up?). This is a disruptive and costly nuisance.

A clean painting environment promoting "high transfer efficiency" is always a good place to start. But that alone does not guarantee a flawless paint finish. A major contributor to poor paint finish quality in plastics is ineffective electrostatic grounding resulting from poorly grounded components.  Yes, something a simple as grounding!  Paint departments use a variety of grounding methods including conductive tape, foil, clip assemblies, and grounding fixtures (of which some are internally integrated).   Each of these grounding methods have varying degrees of effectiveness and cost.  Here are some of the cost factors to consider:

  • Inventory: What are the associated costs to purchase individual grounding components and to monitor / maintain inventory levels?
  • Labor: What are the associated costs to build assemblies in-house, using your own staff, as opposed to buying a complete assembly?
  • Set-up/Clean-up: What are the costs of set-up and clean-up?
  • Effectiveness & Ease of Use: Is the grounding method reliable, repeatable, reusable & cleanable?

Many paint shop process foreman are inclined to think that a "do-it-yourself" grounding solution is the best, cost-effective option.  In reality, a solution engineered to your specific set-up will provide a superior, LOWER-cost result.  Don’t do it yourself!  

  • Customized to the exact requirements of your process. Each is precisely made and consistent.
  • Finished assembly cost is less than the cost to purchase individual components and build them yourself with in-house labor.
  • No scrap, broken or missing parts. Fully built assemblies arrive ready to use.
  • Less administration cost to order, stock, receive and count not to mention – fewer SKUs.

There are many outlets offering standard grounding assemblies and individual components, but it's the application knowledge and expertise that make it work.  Mueller Electric Company has that proven electrostatic grounding solution expertise and field experience.  Mueller offers applications engineering, a wide range of grounding solutions for any plastics painting production line, and samples for testing.  The right solution is a phone call or email away.   

For more information on grounding, read our whitepaper Static Electricity and Grounding in Industry


Free Guide Grounding Plastics  for Painting

Topics: Plastic Painting, Painting Plastics, Test & Measurement

Why don't Alligator/Crocodile clips have Voltage Ratings?

Posted by Ron Malone on Dec 14, 2016 12:46:28 PM

The simple answer is they do not have sufficient, if any, insulation for human protection.  Most alligator or crocodile clips are rated for current (amperage) and not voltage.  Even clips equipped with slip-on insulators do not meet agency requirements for a voltage ratings because the insulator can be moved (without tools) which would expose potentially hazardous bare metal. 


Technically speaking...Most slip-on alligator clip insulators are designed to prevent the clips from shorting against other conductive items.  They are not intended for human protection!  The photos below show a typical alligator clip and slip-on insulator. Clips like this, even with the insulator installed, cannot carry a voltage rating and they should only be used in either low voltage (less than 42V) or “hands free” applications.

 BU-60X.jpg                BU-62-0.jpgBU-60TBO-2.jpg

A "hands-free" application is one where the clips are attached or unattached only when the circuit is not energized or when the electrical potential is less than 42 volts.  If the clips are being used in a "hands-free" environment, the insulators will typically protect against shorting up to 3kV or higher.  Be aware that the voltage rating on the wire used may not be rated this high and thus, may be the limiting test voltage.

Agency Requirements for hand held testing devices: IEC61010-031

To meet IEC61010-031 requirements:

  • The insulators need to be permanently installed and can't be slipped on or off, or moved out of the way; and
  • There must be a guard placed at a specified distance to prevent accidental contact with exposed conductive metal parts; and
  • A finger probe applied at any angle is not allowed to touch any current-carrying exposed metal; and
  • Clearance and creepage distances must be maintained.
  • The junction between the clip and the wire it is attached to must also meet all of the requirements above. Because of this, the clip must have an insulated connector (most commonly a shrouded banana jack) to attach it to a wire. Alligator clips with screw, crimp or solder connections do not meet these requirements.

There are clips with insulators and connectors that meet IEC61010-031 requirements, but not many.  These clips also require the use of test leads equipped with shrouded banana plugs.  They cannot be connected to bare wires


Voltage Rated Clips...   Mueller Electric offers a limited line of fully-insulated alligator clips with voltage ratings as well as test leads with shrouded banana plugs.  For more information & specifications on these products, please click on the appropriate photo below:


To learn more about different types of clips, check out our clip guide.

Topics: Test & Measurement

Mini Test lead Adapters for PC Board Test, Repair & Development

Posted by Paul Kestler on Nov 16, 2016 12:46:38 PM

Having the right tool always makes the job easier. This is particularly true when working with circuit boards at the component level. Many engineers and technicians rely upon these useful miniaturized adapters to perform their test, repair and development work. If you're lacking any of these helpful tools, Mueller Electric's kit provides a convenient solution. Eight micro-tool adapters have been grouped into one Micro-Scale Kit, held neatly in a fabric Velcro wallet.

One end of each micro-tool plugs into any standard test probe. The opposite end of the micro-tool is the miniaturized instrument.


The Micro-Scale kit includes:

  1. Standard probe to magnetic end
  2. Standard probe to insulated alligator clip
  3. Standard probe to insulated hook grabber
  4. Standard probe to insulated plunger
  5. Standard probe to battery current measurement probe
  6. Standard probe to insulated needle probe
  7. Standard probe to insulated male breadboard pin
  8. Standard probe to insulated female breadboard pin


To Purchase the Bonus Pack, containing the

BU-P5519A Premuim Test Lead set AND the

Micro-Scale Kit, click on the blue button.


Get Micro-Scale Special Offer


Contact Mueller Electric




Topics: Test & Measurement