460V three phase is a common electrical specification for running industrial equipment. In this article, you will learn about the 460V three phase, review its wiring configurations, and compare the 460V vs 480V.
460V Three Phase Configuration
Every equipment that consumes electricity has specific input ratings relating to voltage, phase, and frequency. Generally, in the USA, the standard supply for domestic/residential areas is 120V, single-phase, and 60Hz. But, in the case of industrial equipment, which is mostly three-phase, voltage ratings are much higher. For example, 480V is a standard distribution voltage for industrial use according to ANSI and IEEE. However, voltage drops between the supply and point of use mean that specification of equipment in such configurations is at 460V utilization voltage. Thus, 460V in industrial applications refers to the equipment rating and not the supply voltage.
Now, the previous section establishes that 480V is the standard supply for a 460V three-phase device. So, this section reviews common wiring configurations to attain this specification. Two common connections are the three-phase four-wire wye and the three-phase three-wire delta.
Three Phase Four Wire Wye Configuration
Generally, this configuration is growing in popularity for power supply to industrial facilities with 460V three-phase devices due to its suitability for long-distance transmission and the presence of a neutral wire. Also, it serves both single-phase and three-phase. Moreover, it consists of three hot wires and one neutral wire. The voltage between any two phases is 480V, while the voltage between any phase and the neutral is 277V, as the diagram below shows.
Three Phase Three Wire Delta
In comparison to the four-wire wye connection, the three-wire delta connection is limited in application. Due to the absence of a neutral wire, it suits transmission over short distances only. However, this configuration suits equipment with high starting torque and distribution systems. Another advantage of the delta connection for supplying 460V three-phase equipment is its reliability. Altering the supply achieves a range of nominal service voltages including 240V, 400V, 480V, and much higher values.
460V Three Phase Wiring Code
Another important consideration when dealing with 460V three-phase systems is the color-coding of the wires. Regulatory bodies such as the National Electrical Codes (NEC) covers USA and Canada, and the International Electrotechnical Commission covers Europe and provides color-coding guidelines. Moreover, these guidelines vary according to voltage rating and the number of phases. For instance, the NEC gives the following recommendations for 240V and 480V three-phase systems as the table below shows.
|Ground||Green, green/yellow stripes, or bare||Green, green/yellow stripes, or bare|
460V vs 480V
460V and 480V are common voltage levels for three-phase systems. In industry, there’s frequent debates if these two voltage levels imply the same thing. Thus, the following clarifies what each represents:
- According to NEMA, 460V three-phase is a “Utilization Voltage”, while 480V is a “Distribution Voltage”. Simply put, 480V is what the power source supplies, but the equipment within the system is designed to operate at 460V due to power losses. Although the drop in the voltage may not be exactly 20V, it will be within that range. So, equipment in these systems possess built-in tolerance to operate within a range of voltages, with 460V being the nominal voltage.
- Both 460V and 480V are for industrial systems. Domestic systems have lower power demands, so operate with lower voltage levels. In the USA, residential utilization voltages are 110/115V and 220/230V for single and three-phase respectively. Distribution voltages for residential use are 120V for single-phase and 240V for three-phase.
- Depending on the connection in use, a 480V supply could be for three-phase or single phase. In contrast, 460V is only associated with three-phase devices.