top of page
Energy Code Analysis in Houston TX 1920_edited.jpg

Electrical contractor, Blanco Electric offers
fault current calculation services to
clients in Houston and elsewhere in Texas

Fault current calculations are a critical aspect of power system analysis. As electrical contractors in Houston, we perform these calculations to determine the magnitude of the currents that flow during a fault or short-circuit in an electrical system.

A fault occurs when one or more conductors come into unintended contact with each other, creating a low impedance path for the current to flow. This can result in extremely high currents, which can cause major damage to electrical equipment and represent a serious safety hazard for personnel.

What are the primary purposes of fault current calculations?

Equipment selection and rating


Determining fault current levels allows our electrical engineers and our clients to select the appropriate equipment, such as transformers, switchgear, and cables, able to withstand the maximum fault current without damage. This equipment must be rated to handle fault currents to ensure the safety and reliability of the client's electrical system.

Protective device coordination

Fault current calculations help Belco engineers to design and coordinate protective devices, such as circuit breakers and fuses, to ensure they can interrupt the fault currents and isolate the faulty section from the rest of the system. Proper coordination of protective components of a system minimizes the impact of a fault on the overall system and decreases the potential for cascading failures.

Arc flash hazard analysis

Calculating fault currents precedes arc flash hazard analysis. An arc flash is an explosive release of energy caused by an electrical arc: it is a very serious safety hazard for the personnel working near your electrical equipment. By determining the fault current levels, our engineers can calculate the incident energy associated with an arc flash event, and define appropriate safety measures such as personal protective equipment (PPE) and safe working distances.

System stability and reliability

Analyzing fault currents helps our electrical engineers assess the impact of faults on the overall stability and reliability of your electrical system. This service provides valuable insights into potential issues, such as voltage sags, equipment stress, and the need for system upgrades to handle increased load or capacity requirements.

In what situations do you need to perform fault current calculations?

Electrical contractors like Blanco Electrical LTD perform fault current calculations for clients to ensure the safety and reliability of their electrical system.

Based on our experience, here are 7 types of situations in which it is necessary to proceed with fault current calculations:

New construction

During the design phase of a new building, we perform fault current calculations to assure the general contractor, the architect, and the owner of the building that the electrical system is designed to handle the maximum fault current levels, and that the appropriate equipment had been selected.

System upgrades and expansions

Our clients ask us to perform fault current calculations when they consider expanding or upgrading an existing electrical system, and need to determine if the planned changes impact fault current levels. They also want to know if their existing equipment and protective devices can handle the new conditions.

Equipment replacement

When clients replace part of their electrical equipment (e.g. transformers or switchgear), they ask us to perform fault current calculations to ensure that the new equipment is rated to handle the fault currents in their system.

Load changes

The fault current levels in an electrical system will be impacted by significant changes in the connected loads (e.g. addition of large motors, installation of other equipment). We perform these calculations to verify that the electrical system can handle the new fault current levels.

Changes in utility supply

When the utility supply undergoes major changes (e.g. addition of a new substation, change in the available short-circuit current), we perform fault current calculations to assess the impact of these changes on the electrical system of a facility.

Conducting studies on protective device coordination

Blanco Electrical LTD performs fault current calculations in the framework of protective device coordination studies. These studies are conducted to ensure that protective devices (e.g. circuit breakers, fuses) are properly coordinated to minimize the impact of a fault on the overall system.

Arc flash hazard analysis

When we perform an arc flash hazard analysis, we do fault current calculations to determine the incident energy levels associated with the arc flash event. This enables our engineers and our clients to define appropriate safety measures and PPE requirements.

Fault current calculations: Process

When the engineers at Blanco Electric LTD do a fault current calculation for a client, the process followed will slightly vary depending on the type of building/facility. We outline here 3 categories of facilities in the Houston area for which we do fault current calculations. If your facility does not match any of these 3 categories, please call us to tell us what type of environment you need this service for. It is 99.99% likely that we can perform fault current calculations in your specific facility.

(a) Category 1 - Educational Facilities: Fault Current Calculations Process

​Information gathering: We begin by collecting all relevant documentation on your electrical system, such as single line diagrams, conductor sizes, lengths, transformer sizes and impedance values, generator specifications, and any other electrical equipment details documented by the general contractor who built the facility.

Utility fault current determination: We contact your utility company and request the available short-circuit current at the primary side of the service transformer. We will use the data as the basis for our fault current calculations.

Electrical system modeling: Using a specialized software, we model your educational facility's electrical system, incorporating all the data we gathered. This helps us accurately simulate the fault current at various locations in your system.

Fault current calculations: We run the fault current simulations in our software for different types of faults, such as three-phase, line-to-line, line-to-ground, and double line-to-ground faults. This leads us to identify the maximum fault current levels at each point in your system.

Protective device evaluation: Based on the fault currents we calculated, we verify that the ratings of the protective devices (e.g. circuit breakers, fuses) are adequate for interrupting the fault currents. We recommend necessary adjustments if required.

Documentation: Finally, we prepare a detailed report of our fault current calculations, including the methodology, the assumptions, the input data, and our results. We present you our findings, and discuss with you any necessary upgrades to your electrical system. We will do the upgrades if you want us to do so.

(b) Category 2 - Industrial Facilities: Fault Current Calculations Process

Information gathering: Similar to the case of an educational facility (see above), we collect all relevant information on the electrical system of your industrial facility.

Motor contribution evaluation: As you are certainly aware, large motors can contribute significantly to fault currents in industrial facilities. We obtain the specifications of all large motors in your facility in order to include their contributions in our fault current calculations.

Performing calculations for various operating scenarios: All industrial facilities have their own specific operating scenario: normal operations, maintenance periods, and emergency operations. We perform fault current calculations for each scenario to ensure system safety under all operating conditions.

Coordination of protective device assessment: We perform our fault current calculations at various points in your system to ensure proper coordination between upstream and downstream protective devices. This ensures that only the nearest protective device operates during a fault, thereby minimizing the impact on the rest of your system.

Arc flash analysis: We perform an arc flash analysis using the values obtained through our fault current calculations to determine incident energy levels and the appropriate personal protective equipment (PPE) requirements for your personnel working on the electrical equipment.

Documentation: Similar to how we complete the fault current calculations process for an educational facility, we prepare a detailed report on our fault current calculations and we present you the findings and recommendations. If applicable, you can decide to have Blanco Electric LTD do all necessary upgrades.

(c) Category 3 - Commercial Buildings: Fault Current Calculations Process

Information gathering: We collect all relevant data on the electrical system of your commercial building, just as we do for the other two types of facilities.

Harmonic effect integration: Commercial buildings usually have significant harmonic-producing loads: (variable frequency drives [VFDs] and electronic ballasts). We include the harmonic effects in our fault current calculations to ensure the protective devices can handle the resulting distorted waveforms.

Analysis of multiple utility feeds: Some commercial buildings have multiple utility feeds for redundancy. This is almost always the case with large buildings housing a large number of tenants. We perform fault current calculations for various combinations of these feeds to ensure your electrical system can safely handle the fault currents under all possible scenarios.

Protective device evaluation: Based on our fault current calculations, we verify that the ratings of the protective devices of your system will actually interrupt the fault currents. We will make necessary adjustments if required.

Arc flash analysis: We perform an arc flash analysis using the calculated fault current values, similar to what we do in an industrial facility.

Documentation: We complete our fault current calculations mission by preparing a detailed report on our calculations, and we present you the findings of the report. You can then decide to trust Blanco Electric LTD with implementing any necessary system upgrade.

As a Houston-based electrical contractor, Blanco Electric LTD performs fault current calculations missions for many categories of facilities. When we turn over the documentation of our calculations to your organization, you can immediately put our findings to use and correct any safety shortcomings in your electrical system to ensure the safety of your personnel and third-party contractors within your facility. We hold ourselves to the highest standards of professionalism in effect in the City of Houston and in the State of Texas.

bottom of page