How To Choose the Right Circuit Protection Devices

The most important aspect of selecting circuit protection devices for trucks, off-road equipment and other mobile equipment is a complete understanding of the system to be protected. Because the circuit protection design is usually one of the last considerations, and time is always at a premium, this aspect of electrical system design is usually rushed. Mechanical Products, a manufacturer of thermal circuit protection devices, recommends an easy seven-step process for effectively selecting your overcurrent protection solution.


1. Determine what is to be protected and why. i.e.-device(s), component(s), circuit(s).

2. Determine how damaging overcurrents and natural inrush currents and surges can be developed in those items listed above.

3. Determine where a current interruption device should be placed. Depending on placement, You will need to consider the type and size of automotive wire and cable and electrical connector

4. Calculate the magnitude and duration of the potential fault currents of Step 2 as they relate to those items listed in Step 1. Determine maximum voltage requirements of the protective devices you will use. It is also important to consider what kind of environmental elements the circuit protection device will be exposed to.


If your circuit protection device is going to be subject to harsh environmental elements, you might want to consider weather-proof or marine rated components.

5. List the supplementary requirements for the protective device. What will it be connected to? i.e. auxiliary switch for an alarm circuit, lighted actuation, environmental considerations, electrical trip, relay trip, etc.

6. Determine the regulatory requirements. Depending on your application, you might be required to circuit breakers, automotive fuses and other circuit protection devices that are SAE rated or UL rated.

7. Choose a circuit protection device that meets the requirements of your application.

To offer more details on step 1. What is to be protected and why, keep the dynamics of circuit protection in mind. In order to avoid nuisance trips attributable to start-up inrush and harmless surges with power systems, it is necessary to provide a margin of tolerance between the steady state current of the circuit and the rating of the protector. In general, the recommended margin for fuses is 25%; for circuit protectors, 15 to 20%. Additionally, there is a trip window or tolerance on the calibation of the protection device.

For precise circuit breakers, this tolerance is between 25% and 35%. This means that a circuit breaker will hold 100% and will trip between 100% and 125% to 135% within the hour. Based on this common industry specification as an example, a 10 amp rated protector can be expected to hold 10 amps or 100%. It can also be expected to trip at 12.5 or 13.5 amps within an hour. The expected trip point is governed by the Maximuim Ultimate Trip (MUT) specification. In this example, the Maximum Ultimate Trip is 125% to 135%, depending on the circuit breaker’s specifications.

The most important considerations when matching potential fault protection to a circuit protector are the I2t factor and the fault trajectories. The I2t factor proects the potential for Circuit-Breaker-Trip-Curvedamage in a component – i.e. automotive wire, motors, power rectifiers, transformers, etc. Generally, this factor is a measure of what a device can absorb and still survive. The measure is a function of current in amps versus time in seconds.

The fault trajectory is simply a graphic representation of a fault and, if it is specified as a current in amps and time seconds, then bot hthe I2t and fault trajectory can be put on the same graph. The point at which two lines cross on the graph represents the condition where circuit or component damage can be expected. For further clarification, the trip curve of the specified circuit breaker can be superimposed on this graph, giving a visual indication of the level of protection offered by the circuit breaker and its suitability for the application.

It is necessary to consider all of the aspects of the circuit protector that affect its published operating characteristics when considering its trip curve graph. Specifically, variations in performance can be encountered when factoring:

1. Position differences in magnetic circuit breakers

2. Ambient temperature changes in fuses, thermal circuit breakers and magnetic circuit breakers

3. Potential for overreaction to inrush currents often encountered in magnetic breakers

4. Effect of voltage on the published trip characteristics of magnetic circuit breakers.

Having considered all these variables, the designer must also weigh the ancillary product considerations of a circuit protection, i.e.- allowances between product cost and performance, supplementary requirements, and regulatory approvals.

Waytek Is Now An Authorized Distribution Partner For Mechanical Products New Series

Minneapolis, MN March 2014 - Waytek, Inc., a leading distributor of electrical wiring supplies, connectors and circuit breakers, announces that they have been selected to be a Mechanical Products (MP) authorized distributor partner for their new Series 17 line of Thermal Circuit Breakers.

The Series 17, manufactured in the U.S.A., is a main or branch circuit breaker used in accessory or auxiliary direct circuit (DC) electrical systems operating in harsh environments to provide protection in the event of overload and/or short circuit interruptions. The Series 17 is available in 25 – 100 amp ratings (up to 200 amp circuit breakers will be available in late April) with stainless steel terminal SEMs nuts as an option.

The new Series 17, which is designed for industrial, transportation, and vehicle accessory manufacturers, includes Agricultural, Construction, Marine, Material Handling, Emergency Vehicles, Automotive Lifts, Battery Chargers, and Recreational Vehicles and Trucks industries. The series is available in Type I, Type II, and Type III.

The Series 17 offers designers and end-users improved access to wiring and operation, corrosion resistant studs and hardware, superior moisture sealing, a variety of mounting options, higher amperage ratings, and potential use of bus bars while enclosed in a durable, sealed thermoplastic housing. The Series 17 is compatible to existing mounting profiles while offering new features and mounting styles that allow for next generation designs.

The MP Series 17 offers new Side-by-Side Surface and Easy Access, 90-degree Panel Mount designs, in addition to standard mounting profiles. Surface Mount configurations are available in 1/4” and 3/8” heavy-duty stainless steel terminal studs. Panel Mount units are available with 1/4” brass, nickel-plated terminal studs.

The MP Series 17 is designed as a drop-in replacement for existing surface and panel mountable configurations in the market today. These high quality breakers are assembled in the USA and available only at Authorized Distribution Partners like Waytek, Inc.

The NEW Series 17 Thermal Circuit Breakers are an excellent complement to MP’s existing Series 18 breakers, also designed for harsh environments, available in 2 through 60 amp ratings. For additional information on these and other high quality MP thermal circuit breakers, visit Mechanical Products at

About Waytek: Since 1970, Waytek has been providing electrical wiring supplies to OEMs in the truck body & trailer, construction machinery & equipment, agricultural equipment, and emergency vehicle markets. Waytek maintains a large inventory of over 10,000 different electrical supplies in stock. Waytek prides itself on the philosophy “If it’s in the catalog, it’s in-stock.” To view the Mechanical Products Series 17 thermal circuit protection, go to

Mechanical Products' thermal circuit breaker

About Mechanical Products

MP has been a leading supplier of thermal circuit protection since 1943. MP circuit breakers are used in thousands of commercial and industrial applications ranging from medical equipment, appliances, lighting, and communication devices, to recreational and off road vehicles/equipment, and electrical protection devices. MP has been management owned and operated since 1998, is headquartered in Lombard, Illinois and maintains manufacturing capabilities in the US and overseas.

Waytek Now Offers Updated Electronic Catalog Ready For Download

Minneapolis, MN, February 2014, - Waytek, Inc., a leading distributor of electrical wiring supplies and connectors for the mobile equipment market, is pleased to announce the addition of their new online electronic catalog.

The catalog can be accessed and downloaded from Waytek’s website or by clicking here. It offers electronic functionality to help users quickly find the products they’re looking for regardless of how they prefer to search the electronic catalog.

Waytek Catalog #227 is the latest catalog in the company’s 44-year history and includes more than 10,000 parts and descriptions. The electronic version of Catalog #227 offers several electronic methods of finding products, descriptions, and technical specifications that are more effective than the traditional catalogs. This efficiency allows users to access and review key information quickly for any equipment-building project.

The entire electronic Catalog #227 can be accessed from the website or download to the user’s desktop for quick reference and ease of use.  The download process allows users to save and access the entire catalog with a few clicks of the mouse.

Simply clicking on a desktop icon provides the user with instant access to all of the electronic catalog’s features. Items in the electronic catalog are linked to the website for additional product information, current pricing, data sheets, and other products the user will need. Once on the website, orders can be placed for all your electrical supply needs.

It’s easier to find products using the electronic catalog rather than a traditional hardcopy. Products can be found by flipping page-by-page, clicking on index descriptions that are linked to specific products, or users can jump to the page needed by simply entering the page number. A tile function also allows the user to see all pages on one screen and select the pages they need from there.

A features button allows users to flag and add notes to frequently used pages for ease of reference. The notes tool is a great way to add reminders for individual products on pages that are frequently used.

Our philosophy, “If it’s in the catalog, it’s in stock,” has just taken on a whole new meaning. Check it out for yourself by visiting our website at

Image of Waytek catalog

About Waytek: Since 1970, Waytek has been providing electrical wiring supplies to harness manufacturers and OEMs of truck body & trailers, emergency vehicles, construction machinery & equipment, and agricultural equipment markets. Waytek has an inventory of over 10,000 different electrical supplies.

Waytek Adds Picker Components To Their Existing Line Of Equipment Relay Options

Minneapolis, MN, January 2014, - Waytek, Inc., a leading distributor of electrical wiring supplies, connectors, and relays, is proud to announce the addition of Picker Components to its broad, in-stock relay offering of OEM manufacturing electrical components.

Picker Components builds a broad line of electro-mechanical and solid state relays and has become a quality leader among relay manufacturers. Picker’s automotive relays use proprietary silver tin indium oxide contacts that provide superior contact performance with respect to inrush current. Picker relays are available sealed and unsealed, with and without mounting brackets and as plug-in or PCB mount configurations.

Waytek offers Picker Components’ extensive line of Automotive, Power, Signal and Solid State relays, stocking the popular mobile equipment versions. Picker Components’ offering includes the PC7150 family 150 amp PCB power and maxi ISO relay with two 1/4″ and three 3/8″ terminals. This part also brings with it a new relay connector for the 150 amp relay.

Waytek offers complete relay lines from TE/Bosch, Song Chuan, Hella and now Picker Components. “Regardless of your preferred relay, Waytek carries the most popular lines, so you can order your relays, wire, connectors, and loom from one company and have it shipped the same day,” said Jim Keister, marketing manager, Waytek, Inc. “Picker Components round-out our relay inventory and allow us to offer a full family of high current, mini ISO, micro ISO BS maxi ISO relays, ISO 280 micro relays, ultra micro relays, and appropriate connector lines.”

All new relays and connectors are in-stock at Waytek and ready for same day shipping for all orders placed by 4:30 pm CST Monday-Friday.

Since 1983, Picker Components has manufactured one of the broadest lines of relays in the marketplace. “We want to offer our customers a wide-selection of relay components and connectors to meet their OEM requirements,” said Bob Lamoreaux, President of Waytek. “Quality manufacturers such as Picker Components help us meet these demands for our customers.”

These relays have been added to more than 10,000 quality electrical wiring supplies already in-stock at Waytek’s mid-west location. All products are on the shelf and ready to be picked, packed, and shipped.

Image of Waytek picker components

About Waytek: Since 1970, Waytek has been providing electrical wiring supplies to OEMs in the truck body & trailer, construction machinery & equipment, agricultural equipment, and emergency vehicle markets. Waytek maintains a large inventory of over 10,000 different electrical supplies. Waytek prides itself on having the “Right Parts, In Stock, and delivered On Time.” To view Picker Components in Waytek’s product line, go to

About Picker Components: Since 1983, Picker Components has manufactured one of the broadest lines of electro-mechanical and solid state relays. Picker Components manufacturing facilities are ISO9001-2000 and ISO14001: 2004 certified and have been issued an ISO/TS 16949:2002 certificate by TUV SUD. Picker Components is a leader among relay suppliers. Offered at a competitive price, they provide the highest quality relays in the market.

Automotive Wire Gauge Guide

Automotive-Wire-On-ShelfThe automotive wiring you select for manufacturing and maintaining vehicles and equipment is an integral part to keeping electrical systems reliable. Not only is the type of wire you select important, like automotive gpt primary wire or automotive cross-link wire, but it’s also important to choose the best automotive wire gauge size based on your application current draw, potential electrical resistance and voltage drop.

Voltage Drop & Automotive Wire Gauge Guide
Voltage drop is the amount of voltage lost over the length of the automotive wire or cable. Voltage drop changes as a function of the resistance of the wire and should be less than 2% if possible. If the drop is greater than 2%, efficiency of the equipment in the circuit is severely decreased and life of the equipment will be decreased.  As automotive wire lengths get longer, electrical resistance builds up until it forces the voltage down below a usable level. At that point, up-sizing the wire gauge will restore the voltage to its intended level.

Voltage drop can be calculated using Ohm’s Law: Voltage Drop = current in amperes x resistance in ohms. 

For a more convenient calculation, voltage drop calculators and automotive wire gauge guides, like the chart shown below, can be helpful reference tools. This wire gauge guide shows the maximum run of wire that is recommended for 22 through 4/0 automotive wire gauges based on different current draw ratings.


Disclaimer: Many factors can affect the performance of the application, such as voltage, temperature, load, etc. With so many variables, Waytek is providing this wire gauge guide as a general guideline only. Please refer to your design engineer for final decisions.

How To Reduce EMI with Twisted Pair Shielded Cable

TractorCabAs technology advances in trucks, emergency vehicles, ag equipment, construction equipment and more, the need to place more electrical and electronic devices such as computers, CAN J1939 systems, mobile media and DC motors and controllers has dramatically increased. Electrical and electronic systems are more complex than ever, and size and weight constraints in vehicle and equipment design are more crucial than ever for maintaining fuel economy and emissions. When you pack a large amount of electrical and electronic devices into a very confined space, electromagnetic interference (EMI) from crosstalk can cause each system to malfunction. Containing EMI is vital to the life of your electrical system.

What is EMI?

EMI is a process by which disruptive electromagnetic energy is transmitted from one electronic device to another via radiated or conducted paths, or both. In an automotive electronic system, EMI can adversely affect the performance of an integrated circuit internally, as well as that of other electronic components in close proximity.

EMI problems can manifest themselves as simple nuisances such as static on the radio. Or they can create a dangerous problem such as loss of control of the vehicle. Special care must be given to “mission critical” systems; especially those that deal with the control and safety of the vehicle. Some of these internal systems include:

  • Collision avoidance radar
  • Console applications
  • Navigation-radio combination
  • Power steering module
  • Infotainment head unit
  • Airbag inflator
  • ECU and other module connector
  • Tire pressure monitoring
  • CAN Bus
  • DC motors
  • Ignition system
  • Engine control module
  • Electronic Braking Systems
  • Fuel Control Systems
  • Adaptive cruise control

Reduce EMI with “The Twist”

“The Twist” refers to twisting of a pair or pairs of wires to reduce crosstalk, RFI and EMI. In a twisted pair, two conductors of a single wire are twisted together in order to carry equal and opposite signals so the destination detects the difference between the two, which is known as differential mode transmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields and tend to couple to both wires equally. The noise thus produces a common-mode signal which is canceled at the receiver when the difference signal is taken. Twisting the wires to reduce inductive coupling reduces the noise (in comparison to no twisting) by ratios varying from 14:1 (for four-inch lay) to 141:1 (for one-inch lay). In comparison, putting parallel (untwisted) wires into steel conduit only gives a noise reduction of 22:1. (EETimes)


Figure 2 (left) demonstrates crosstalk between wires: a magnetic field generated by current flowing in wire A causes an unwanted current to flow in wire B. (EETimes)




In Figure 3 we see the canceling effect of twisted pair wire. When an interfering signal is applied equally to both sides of the twisted pair, the interfering signal is neutralized and destroyed. (EETimes)

TwistedPairWireWhen it comes to twisted pair cable and wire, there is unshielded twisted pair cable (UTP), and shielded twisted pair cable (STP), wrapped with a metallic foil to shield electrostatic and increase the speed of data transfer. UTP does not have any shielding, but it’s still very capable of handling imbalances that interfere with data transfer.



STP cabling, also called shielded control cable, works by attracting electromagnetic interference and neutralizing it with a grounded cable. Problems can arise if that cable is improperly grounded. If not grounded properly, STP may lose its ability to cancel noise. This type of cabling is also bigger and more sensitive to work with than UTP cable. To make the best use of shielded twisted pair wiring, it should be used in industrial settings where the surrounding equipment gives off elevated amounts of electromagnetic interference, and the installer should pay very special attention to ensuring it is grounded properly.

Since unshielded twisted pair cabling has no foil shield and relies on the way the pairs inside the cabling are twisted, it is more susceptible to electromagnetic interference in industrial settings. UTP is a good choice for CAN systems and similar network cabling systems. UTP is smaller than STP cables, so it’s easier to work with, especially in the space restricting designs of vehicles and equipment panels.  UTP transmits data just as fast as STP, and it is more cost effective.

When properly installed and maintained, both unshielded twisted pair cable and shielded twisted pair cable will do quite well in their applications. When your application is industrial and very high in electromagnetic interference, shielded cable can add an extra line of protection. Nore information on shielded control cable here and CAN bus J1939 cable here.

Some data was used from an EE Times Article: Use a twist (and other popular wires to reduce EMI/RFI)

Fight Corrosion Costs with Battery Terminal Covers

The Federal Highway Administration estimates that corrosion costs the nation’s transportation industry and its infrastructure $30,000,000,000 every year.

battery-terminal-coversOver the past 15 years, it is estimated that the costs associated with corrosion caused by anti-icing chemicals have increased more than tenfold, partly due to the increased use of magnesium chloride (MgCl) and calcium chloride (CaCl) as deicing chemicals, instead of NaCl. MgCl and CaCl latch-on to surfaces more aggressively than NaCl making them harder to remove, plus even in their crystal form, they draw moisture out of the atmosphere and remain a corroding solution.

Corrosion is a huge problem for electrical systems in trucks, trailers and any on-road equipment, especially related to battery performance. Battery terminal covers are an inexpensive and simple solution to protecting your battery cables and battery connections from corrosion.Typically made of vinyl or rubber material, battery terminal covers are flexible and easy to install over copper eyelets and battery lugs of any size from 18 gauge to 4/0 gauge. They protect the battery cable and connections from shorting and keep fleets and vehicles running. Battery terminal covers are usually sold in black and red for color coding and easy identification of cables.

E•COPILOT Fuel Saving Devices



E•COPILOT is a patented solid state fuel saving device that plugs-in to Class 7 or 8 ECMs and manages available engine power based on actual demand, in order to maximize fuel economy. In less demanding driving situations, horsepower is managed to allow only the performance needed. If a vehicle is pulling a load or climbing a grade, the driver can access all the horsepower. It’s like re-sizing the engine for each particular portion of a vehicle’s day. The result is all the power needed, improved fuel economy, improved safety and reduced maintenance, without affecting your truck’s manufacturer warranty. 


The E•COPILOT device is a small box that commonly mounts behind a dash panel. By monitoring a number of data points within the vehicles ECM’s and an installed weight load sensor, the E•COPILOT manages the driver’s access to engine power to optimize fuel economy and performance.

When an engine is selected for a vehicle it must be sized to haul its heaviest load, climb the steepest grade and meet its greatest demand. However, in most applications the vehicle spends much of its day hauling less than its full load weight and operating in less demanding situations. The E•COPILOT provides only the power needed while optimizing fuel economy. Drivers who operate vehicles with E•COPILOT installed say they don’t notice a difference in performance.

The E•COPILOT is much more than just a load based engine or transmission control. While some OE engine and transmission manufacturers offer load based fuel economy configurations the E•COPILOT’S highly patented technology works very differently.

In government recognized independent lab studies and field tests, the E•COPILOT has proven fuel economy benefits of as much as 11% improvement on OE load based engines and transmissions.



  • Produces average FUEL SAVINGS of 7% or more
  • Improve safety by eliminating aggressive acceleration
  • Reduce maintenance costs: Drive train, premature tire wear
  • No driver training / incentive required
  • Device requires no maintenance
  • Drivers always have the power needed without wasting fuel
  • Assets stay with fleet as it’s transferred to the next vehicle


  • Works with 2002 and newer North American class 7 and 8 trucks
  • Q3 2014 most medium and light duty vehicles will be available
  • Accredited independent lab proven TEST RESULTS
  • Meets or exceeds all required safety standards
  • Commonly installs in less than two hours
  • Does not affect manufacturer’s warranty


The E•COPILOT provides fuel economy benefits in APPLICATIONS where the payload varies. Fuel economy improvements of 10% or more have been seen with fleets that have frequent stop and go and occurrences of acceleration.

GROCERY:  One of the largest grocery companies in the US achieved a 3.7% fuel economy improvement.  Their delivery trucks average 7.5 miles per gallon and over 135,000 miles per year.  Average fuel savings per year was over $2,150.  ROI in less than 9 months.

SOLID WASTE TRANSFER: A municipal company with a fleet of solid waste transfer trucks in the US achieved results as high as 13.1% fuel economy improvement.  Their transfer trucks average 4 miles per gallon and about 30,000 miles per year.  ROI in less than 10 months.

FUEL TRANSPORT:  One of the largest fuel transport companies in the US achieved a 5% fuel economy improvement.  Their transport trucks average 7.5 miles per gallon and over 100,000 miles per year.  Average fuel savings per year was over $2,650.  ROI in less than 8 months.

DAIRY TRANSPORT:  One of the largest dairy transport companies in the US achieved an 8% fuel economy

How to Protect Electrical Connections from Corrosion, Pull-out and High Repair Costs

Reducing recurring electrical problems and repair costs is always on the minds of fleet owners. Electrical connectors must operate in adverse conditions like extreme heat, extreme cold, vibration, strain, snow, rain, moisture and chemicals. These conditions cause electrical connector corrosion and wires to pull-out, resulting in equipment downtime and high repair costs.

Electrical-Connector-CorrosionCorrosion damage is estimated at over $23.4 billion in the transportation sector. Wiring and lighting is the most frequent corrosion problem in maintaining fleets. These issues often stem from faulty electrical connections. Equipment downtime often results in hundreds to thousands of dollars in violations, repair costs and lost opportunities.

Heat-shrink-electrical-connectorsUsing a high quality sealed electrical connector can protect against moisture and contaminant causing corrosion. The simplest way to prevent corrosion damage is to use heat shrink terminals and electrical wire connectors in place of non-insulated, vinyl or nylon insulated options. Heat shrink electrical connectors are constructed with adhesive lined polyolefin heat shrink tubing to seal-out moisture. Their initial cost is a little higher than non-insulated, nylon or vinyl electrical connectors, but they offer strong environmental protection, easy installation and durability, making them an extremely valuable selection.

New Space and Weight Saving MCASE Fuses

MCase FusesThe MCASE fuse is the newest cartridge style fuses for automotive applications. Designed and patented by Littelfuse, the MCASE fuse was developed as a space and weight saving version of the JCASE cartridge style fuse.

MCASE fuses have female terminals with 2.8mm terminal footprint. The miniaturized footprint allows for optimal space usage. They are time delay fuses and can handle interrupt currents up to 1,000A. Rated for 32 volts, and currently available in four amp ratings: 20A, 25A, 30A and 40A, color coded for easy identification.


With similar rating characteristics as the JCASE fuse, but nearly half the size, MCASE fuses are an optimal space and weight savings circuit protection option for vehicle and heavy mobile equipment applications.

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