Mueller Electric Blog

Plant Safety in Grounding & Bonding

Posted by Tim Ulshafer on Sep 21, 2018 1:29:55 PM

When you think of plant safety it is common to think about the things you can see or do. This can be rules and regulations on how to navigate throughout the plant as well as wearing the appropriate safety attire such as hard hats, safety glasses, ear plugs, in addition to fire suits or Kevlar gloves to name a few. So, if the plant has all these things, isn’t it safe? Well, maybe, or maybe not? What about the things you can’t see such as static electricity? Have you considered the need for grounding and bonding?

C clamp barrel fb size 1The number of static electricity incidents reported in the U.S. exceeds more the 250 a year. The reports of these incidents are way more common that you would like to think. Certainly, when electrostatic charge build-up exists in a flammable or explosive environment a very hazardous situation has been created.

Typically these situations can be avoided by installing high quality low resistance grounding/ bonding cables containing clips and clamps. The clips are required to maintain high clamp pressure and the clamps will need to have a paint piercing point to be effective in garnering a solid metal on metal connection to reduce resistance and reduce static. The clips and clamps can be connected to a braided copper cable or better yet, a stainless steel wire rope which tends to hold up better in industrial applications. Make sure the connections to the cables are tight and always test the assembly for low resistance, the closer you get to 1 OHM the better.

Grounding / bonding cables don’t always guarantee static dissipation. Many times a grounding or bonding cable is attached to an object (tank or pump) which has been coated for protection. These types of coatings can impede the clip or clamp’s ability to make a solid metal to metal connection, which in turn, increases the resistance within the grounding structure. With increased resistance comes the possibility of electrostatic discharge failure. Rust build up on the clip or clamp can also create a coating which will disrupt a solid metal to metal connection. As a result, this too will create an unsafe environment. To avoid these situations, always test your grounding / bonding cable’s connections for resistance at the time of employment. If the resistance is low, great! Move on. If the resistance is high, make the necessary adjustments to insure a solid connection and low resistance. Don’t take a chance, make sure a solid connection is evident before giving it your seal of approval.

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Proper maintenance is also critical to insure that your grounding / bonding equipment is in proper condition to effectively reduce static. Regular inspections of your grounding / bonding equipment are a necessity in any industrial setting. As you know, industrial environments can and will severely test the structural integrity of any device, including grounding / bonding cables and assemblies. Remember, inspect what you expect!

In conclusion, plant safety goes well beyond the need for appropriate attire and traffic flow logistics throughout the plant. Electrostatic discharge, the invisible threat, will need to be addressed as well. High quality, low resistance affordable grounding / bonding equipment is readily available to provide the required protection. Appropriately placed grounding / bonding cables and assemblies along with consistent resistance testing will provide a safe work environment for everyone.         

To read more about grounding and bonding, check out our whitepaper 3 cables 2

Topics: Grounding Metal, Static Electricity Grounding, Grounding Wires, Grounding, Grounding Clamp, Static Electricity, Static Control, Static Electricity Industrial, engineering, custom cables

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


Amperage

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. 

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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.

Material

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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

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. 

 

BU-6161-M-39-24

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

How to Properly Crimp an Alligator Clip Onto A Wire

Posted by Mona Weiss on Dec 7, 2017 1:35:26 PM

 Many people don't know the right way to properly crimp an alligator (or crocodile) clip onto a wire. This blog post (and video) shows how to do it step-by-step.

  

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Step 1: Strip the wire to about 3/8"

 

 

 

 

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Step 2: Bend the stripped wire end over the outer jacket

 

 

 

 

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Step 3: Insert the wire inside the jacket

 

 

 

 

 

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Step 4: Crimp

 

 

 

 

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It's important to fold the wire over the insulation before inserting and crimping because it prevents the wire from being pulled off. 

 

 

 

 

 

 

To browse our alligator clips,click here to see our digital catalog and see where to buy, or click here for our clip selector to narrow your search.  

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

 

Topics: crimping, electronics, crocodile clip, engineering, alligator clip, crimp