What is 208 volts

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What is 208 volts

This page explains 208 volt, including the source of 208 volt, with basic wiring and typical usage.
208 volt is a standard 4-wire 3-phase commercial voltage that comes from 3 distribution transformers wired in parallel or WYE on secondary side. 208V is typically not found in residential homes, but is often found in apartment building, businesses etc.
208 volt WYE electric service offers options for:
-208 volt 3-phase with 3 Hot wires plus a ground.
-208 volt single phase with two Hot wires plus a ground.
-208 single phase with 1 Hot and 1 Neutral plus ground.

Covered on separate page: Commercial electric service with 3-transformers can be wired in series or Delta on secondary side to deliver 4-wire 3-phase High Leg Delta which delivers option for 208V single phase using 1 Hot and 1 Neutral plus ground. High leg delta is covered on separate page: High leg delta

Use only 600 volt wire. Lamp cord, extension cords are not rated 600 volt. Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional. 30 amp breaker use 10 gauge / 120-240 volt 30 amp outlet can be installed on 30 amp breaker only/ use 10 gauge wire ... cannot be connected to 15-20-40 amp breaker. Orange/ #10 gauge wire, with ground ... 30 amp capacity. Safe maximum: 30 x 80% = 24 amps. Buy: 10-2 gauge/ 30 amp 10-3/ 30 amp Southwire electric tools	Yellow 12 gauge 20 amp 120 volt 20 amp outlet can be installed on 20 amp breaker, but not 15 amp breaker/ use 12 ga wire. ... cannot be connected to 30-40 amp breaker. 1 Yellow/ #12 gauge wire, with ground ... 20 amp capacity. Safe maximum 16 amps. Buy: 12-2 gauge/ 20 amp 12-3/ 20 amp NMB is house wiring UF is underground Rolls of stranded wire HOOK UP Wires	White 14 gauge 15 amp 120 volt 15 amp outlet, AFCI, GFCI, timer, switch etc can be installed on 15 or 20 amp breaker. Never connect 15 gauge wire to 20-30-40 amp breaker. White/ #14 gauge wire, with ground ... 15 amp capacity. Safe maximum 12 amps. Buy: 14-2 gauge/ 15 amp 14-3/ 15 amp NMB is house wiring UF is underground
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Non metallic flexible cables must carry ground wire, but do not have hazard of short circuit causing injury from shock. Armored steel cable can be used as a grounded connection, and will protect wires from damage. Metal can be energized from an insulation failure. All conduit ...metal, plastic ... flexible and rigid ... must be attached to structure, and attached to enclosures, boxes. Movement, damage and deterioration are major cause of electrical failure. Buy: Non-metallic flexible conduit Power whip Armored cable Southwire armored cable cutter Pull boxes	Electrical tools must be insulated. Always best to disconnect power, but insulation failure, lack of proper grounding, grounded neutral, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems still pose a risk to anyone working on electric power ... even when breaker is off. Buy: Electrician tools kits KLEIN TOOLS Tools kits IRWIN tools KNIPEX Telephone cable knife Low Voltage Mounting Bracket for Telephone	600 volt 12 ga Stranded wire ot THHN wire is good for conduit with multiple wires ... but stranded cannot be installed under screw terminals on outlets, switches, timers etc without risk ... of heat causing splayed strands ....that come loose ... and begin to arc. Connect stranded to short piece of solid copper wire, and attach solid to screw terminal. Do not solder residential or commercial wiring. Project wire, extension cords, thermostat, bell and automotive wire are not rated for residential or commercial wiring. Only wire maked 600 volt can be used for permanent household wiring. Buy: Southwire 600 volt stranded wire Rolls of stranded wire HOOK UP Wires
Protect wiring from damage Use nipper instead of pliers or screwdriver for removing staples (and nails). Do not damage cable or wires inside cable. -Code says: Cable SHALL BE secured without damage to the outer covering. NEC sec. 336-15 Buy End cutting nippers at Amazon	Electrically insulated tools When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistance and heat on wire and creates possible weak point. Buy tools: KLEIN TOOLS Wire strippers at Amazon Electric Wire Stripping Machine Linesman pliers Utility knife at Amazon	Multimeters Voltage is tested across two separate wires. Ohms or resistance is tested across both ends of same wire. Amperage is tested along one or two points on same wire. Buy: Analog multimeter Multimeters at Amazon Klein multimeter Electric testers at Amazon Clampmeter for testing amp flow on line

GFCI circuit breaker
A GFCI circuit breaker will protect all boxes on circuit.

Circuit must be grounded. Ground wire must be continuous and connected to each piece of equipment.

White wire on circuit breaker must be connected to Neutral busbar inside the breaker panel.

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Tandem breakers

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Choose from 15 to 125 amp
Choose from 15 amp to 200 amp
Eaton CL series circuit breaker
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Double pole GFCI

208 volts is type of 4-wire 3 phase used for commercial electric service.

Fig-1 shows two different electric services; 3-phase 208-208-208-120 volt WYE in background .... and 3-phase 120-240-208 High Leg Delta in foreground.
Each service provides 208 volt to the end user.
Not every commercial service has 208 volt. Larger image

Commercial electric services typically have three transformers as seen in Fig-1.
Transformers are required to convert 3-phase 7200 volt distribution power into usable standard voltages like 208 volt.
Note: A 'service' is the voltage and amount of power (KVa) that is supplied from the grid to the building.

208 volts a standard voltage available in the US, found in commercial applications such as business or apartment buildings.
208 volt is one of several 3-phase electric services that can be installed by the power company. Other standard commercial voltages can include 240, 277, 347, 415, 480, and 600 volt.

Voltages are a function of power generation, mathematics of electricity, transformer configuration, availability of conductive materials, cost, safety, and need for standardization.
Standardization makes it possible to mass produce electric wire, switches, appliances etc. It also means standard electric practices, and allows power companies to generate electric power that is shared across interconnected grids.

Transformers are used throughout the grid to raise and lower voltages as needed. Power plant generators produce four wire 3-phase that is transmitted over 3 Hot wires accompanied by a 4th wire called the Neutral. The Neutral is bonded to a ground (earth) connection at each pole, substation, end user service etc, forming a giant array of grounding that stabilizes the grid.

Four wires are standard for electric transmission and distribution to commercial buildings ... with each hot wire requiring a separate transformer that is needed to reduce high voltage into usable standard voltages ... meaning that each electric service found at a commercial location consists of three transformers.
In some lighter weight services, two transformers are used.

If the three transformers are wired in parallel it is called a WYE (or star) configuration as seen Fig-W1.
Fig-W1 shows a 'phasor diagram' for WYE where the three transformers are represented by curled lines that share a common neutral point. The neutral point represents actual field wiring where all three transformers are connected to the same Neutral wire.

If three transformers are wired in series, it is a Delta configuration as seen Fig. D1 showing the phasor diagram for High Leg Delta where the three transformers are connected end to end and share no common neutral point.
Resource: Difference between WYE and Delta

There are 3 basic transformer configurations that supply 208 volt.

1) 208-208-208-120 volt WYE is covered on this page:
If the commercial location has 3 transformers configured for 4-wire 208-208-208-120 volt WYE service as shown in Fig.W1, then 208 volt is available as 3-wire 3-phase used for 3-phase motors, or as 2-wire hot-to-hot single phase for lights and other uses. In this service, 208 volt is the main voltage.
The 4th wire or the neutral wire is present and when any one of the three Hot wires are used with the Neutral, it yields ordinary 120 volt single phase for outlets etc. Math: 208 volt divided by √3 (1.732) = 120 volt
When an apartment building has 208 volt service, it comes from the WYE configuration.

2) 208-120-240 volt from high leg Delta is covered on separate page:
If the commercial location has 3 transformers configured for 4-wire 120-208-240 volt High Leg Delta service as shown in Fig.D1, then 240 volt is the main voltage and 208 volt is available only as hot-to-neutral single-phase. Math: 240 volt divided by 2 x √3 (1.732) = 208 volt See explanation
The 4th wire or the neutral wire is present at midpoint of 1 transformer. When the neutral and the hot wire from the high leg (phase A) are used, it yields 208 volt single phase. The voltage is still 208, and will work for any appliance, timer, etc that is rated 208 volt, no matter if it is derived via 1 hot and 1 neutral from Delta, or 2 hot wires from WYE.
The use of single phase hot-to-neutral 208 volt from Delta is less efficient than 2 hot wire 208 volt from the WYE configuration, but overall, high leg Delta can deliver more amps per volt than 208 volt WYE and supply the same kVA (power) with less heat loss.
High leg delta is a common service for many local businesses. Resource What is High Leg Delta

3) Covered on separate page:
Industrial transformers and Buck boost transformers are small transformers used onsite at a commercial facility to change service voltages. For example if the location has a lower or higher than standard voltage because of a service problem, or if the business has 480 volt or 600 volt etc service from power company and needs another voltage like 24, 120, 208, or 240 volts etc, then problem can be solved using a small transformer.
The transformers can be wired as a single transformer or in banks of three transformers, depending if single-phase or 3-phase is needed.
If a single transformer is used to convert another another service voltage into 208 volts, then 208 volt is available as 2-wire single phase. Or if three transformers are used to convert another another service voltage into 208 volts, then 208 volt is available as 3-wire 3-phase. The connection can be WYE or Delta or can be wired as an autotransformer, depending on situation.
Resource Industrial and Buck boost transformers
What-is-3-phase-electric

Advantage of 208 service

1) Lower voltage is safer:
Higher voltage services such as 600-600-600-347 and 480-480-480-277 volt are common for larger facilities since higher voltages are more efficient for motors and large area uses, but 600 volt and 480 volt are extremely dangerous and require professional electrician, while 208-208-208-120 volt service is much safer.

2) 208 volt WYE and high leg Delta services both have 120 volt available:
Since most buildings typically have outlets for a coffee maker, cell phone charger, office equipment etc, then 120 volt single phase must be available.
If the building has 600-347 or 480-277 volt services, then a small step-down transformer would be installed to convert higher voltage into 120.

A 208-120 WYE service does not require the cost of additional transformer since 120 volts for outlets is readily available by connecting any hot wire with the neutral. Likewise, the 120-208-240 volt high leg Delta service has 120 available without a secondary transformer.
Resources:
Industrial transformers
Acme wiring .pdf

Overall, the 208 WYE and high leg Delta services can be simpler, cheaper to install, and safer than higher voltage services, but because higher voltages like 277-480 are more efficient for motors and large area uses, it implies that 208 volt services are more common for smaller commercial buildings.

High voltage tools

Buy:
High voltage tools
Electrician tools kits
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Tools kits

Full image	3-phase WYE service at building A commercial 3-phase service consists of 3 transformers that convert 7200 volt distribution power into lower, safer and more usable standard voltages. There are several ways 3 transformers can be wired to achieve various commercial 3 phase voltages. Fig-4W shows a WYE-WYE connection for 3-phase 208 volt service, meaning the high voltage primary side is wired in WYE, and the secondary customer side is wired for WYE. Footnote ... notice how the Neutral is connected to all three transformers in a WYE system, and is also connected to the copper ground wire that will travel to base of pole where it is attached to ground rod. See image Not every commercial installation has 208 volt. How it happens: If a 208-208-208-120 volt service is specified, then the power company installs 3 transformers and connects 4-wire three-phase 7200 volt distribution lines to the primary side. The correct transformers are selected to produce 208 volts on the secondary side. Transformers are also selected by the amount of power (KVA) they deliver to ensure the service can meet expected loading (power use), and then correct wiring is performed to produce 208-208-208-120 Volt WYE on the secondary or the service side. -The resulting service gives 3 wiring options: 3-wire 3-phase 208 volt for motors etc, 2 wire 208 volt single-phase for area lighting etc, 2-wire 120 volt single-phase for outlets... With this type of 3-phase service: 208 is the hot-to-hot line voltage, and 120 is the hot-to-neutral voltage calculated using a ratio of √3 or 1.732. ■ Transformer size is determined by the KVA required by the building. ■ KVA (kilo volt amps) ... volts x amps = watts, so Kilo volt amps = 1 kilowatt or 1000 watts, which is a measure of power. ■ KVA is the capacity of the transformer ... or how much power the transformer can deliver without overheating. Typically a service will have transformers rated for more KVA than needed. ■ KVA should not be confused with KWH (kilowatt hour) which is the amount of billable power used in one hour. ■ If an electric water heater is rated 4500 watts, then it will require 4.5 KVA of power from the transformer, and after 1 hour of continuous operation, it will consume 4.5 KWH of power Resources: Difference between single-phase and 3-phase Identify transformer configurations What is 3 phase
Source for illustration Wye with Neutral and Ground Fig-5W shows the 3 service transformers, the primary and secondary coils inside each transformer, and the wiring needed for a 4-wire 3-phase WYE-WYE service, same as shown in Fig-4W above. Note: WYE-WYE means both the primary and secondary coils in the three transformers are wired in parallel or WYE. To wire in parallel or WYE, each Hot wire (abc or ABC in illustration) is connected to 1 side of 1 coil inside on each transformer at tap H1 or X1, and the Neutral wire (N) connects to other end of all 3 coils at tap H2 or X2. Note that the primary coils and secondary coils share no Hot wire in common. No wire is shared except the Neutral. This means the 7200 volt Hot wires are isolated or insulated from the 208 volt Hot wires to ensure lower voltage wires cannot be energized with high voltage. In a process called magnetic induction, 208 volts is 'induced' on the secondary coils when 7200 volt power is applied to the primary coils. To raise or lower voltage, transformer coils have different number of turns or wraps of wire on the primary and secondary, with more turns on the primary and fewer on the secondary. The proportional relationship between the primary and secondary is called the turns ratio. Using the formula, 7200 divided by 208 = 34.6:1 turns ratio, but remember, in the real world, voltages vary, and the 7200 volt distribution can be higher or lower by a small range, and likewise with the 208 volt service. To accommodate the variations, transformers often have multitaps that let power company connect to a ratio that delivers reliable energy.
Phasor diagrams are simple way to show transformer connections. Phasor diagrams are used for Secondary or Primary, depending on what is being explained. Start with the secondary connections on three transformers, and then simplify into the Phasor diagram that summarizes the wires coming off a transformer bank. There are 3 transformers. each with X1 X2 The phasor diagram represents the X2 taps as a single connected point in center. The resulting 3-phase service is wired in WYE ... so each transformer is wired in parallel with 3 Hot wires and a shared Neutral point.
Fig-4W and Fig-5W above on this page show a 3-phase or 3-transformer WYE-WYE service that is typical for achieving 120-208 volt service. Fig-7W shows a list of phasor diagrams with WYE-WYE shown at the top. Side-by side phasor diagrams are commonly used to abbreviate transformer configurations ... with the primary always on left and secondary on right. Note that the Primary side and Secondary side can be wired in either WYE or Delta. For example, a 3-phase, 3-transformer service doesn't have to be WYE-WYE, it can also be Delta-WYE, Delta-Delta, WYE-Delta, WYE-Open Delta etc as shown in Fig-7W. The choice for how to wire the Primary and Secondary depend on what voltage and power objectives are needed for the building, and other factors having to do with the mathematics of electricity. REsources: See illustrations 3-phase-transformer-banks.pdf 3-phase-transformer-winding-configurations.pdf Three-phase transformer banks connected in a wye-delta or in a delta-wye configuration allow the incoming line voltages and currents to be phase shifted -30° or 30°, respectively.
Service with Delta Primary and WYE Secondary Larger image Original image This 3-phase service provides 208-120 volt WYE or 480-277 volt WYE to a commercial building. Note: The primary side wires are bare, while the secondary outputs that travel into building are insulated. Each transformer has 2 bushings located on the top of the transformer, with a total of 6 bushings. The 3 Hot wires pass through 3 fuses or disconnects before connecting to bushings. We know the primary is Delta because each 7200 volt Hot wire connects to a primary bushing on two different transformers, while the Neutral does not connect to primary side bushings. If the Primary was WYE, then each 7200 volt Hot wire would connect to only 1 bushing, and the Neutral would connect to the other 3 transformer bushings. That's how you identify transformer wiring in the real world. On the secondary side, each transformer has 2 taps where the insulated wires connect. We know the secondary is WYE because 1 Hot wire is taken from a tap on each transformer ... while the Neutral wire connects to one tap on each of the 3 transformers. The secondary side Neutral is the arching black wire that connects to each transformer
Larger image 208-120 volt 4-wire 3-phase Fig 6. is a phasor diagram that shows the wiring connections for 3-phase 208 volt WYE on the secondary side. It does not show coils and connections on the primary side. It also shows the ground wire connection at the Neutral. Throughout the grid, at every pole, substation, transformer, and installation, the Neutral wire is bonded (connected) to the ground or earth to stabilize the grid against overvoltages etc, helping to ensure grid reliability. . At the other end of each of the 3 coils are the 3 Hot wires that carry power from the transformer to the end user's main breaker box. The resulting 3-phase service has 3 Hot wires, 1 Neutral wire and a ground wire that enter the main breaker box, and thus it is a 4-wire 3-phase service (the ground is always required to be present but not counted among the wires).

Larger image 208-120 volt 3-phase service or distribution panel After the 3-phase Power leaves the transformer on insulated wires, it passes through an electric meter that registers billable wattage or kilowatthours (Kwh). After leaving the meter, the electric power passes through a 3-pole safety switch (power cut off) and then enters the main breaker box or distribution panel where the 3 Hot wires connect to the 3-pole main breaker. Each pole on the main breaker connects to a separate busbar where the breakers snap down and draw power for individual circuits. There are 3 ways to use 120-208 volt WYE. a) Snap in a three-pole circuit breaker and draw 208 volt 3-phase power where 3 wires leave the 3 pole breaker and go to a motor circuit or 3-phase water heater etc. b) Snap in a 2-pole breaker and and draw 2 Hot wires for 208 volt single phase. c) Snap in a single-pole breaker and draw 1 Hot and a Neutral wire for single-phase 120 volt. More detail The design inside a 3-phase main box is same across all panel manufacturers (Siemens etc) and all brands of main panels work for WYE or Delta ... with the 3 pole breaker made for 3 Hot wires, plus separate busbars for the Neutral and a ground. Note: Each WYE service has a Neutral available. All 120-208 volt services will be 4-wire and will include the Neutral. However a small WYE service that supplies power to a 3-phase wastewater pump etc might not run the Neutral into the pumphouse if 120 for outlets etc is not needed. Note: There are Delta services that do not have a Neutral. Note: No matter if a Neutral is available in the building, all services WYE and Delta are required to have a ground connection. Resources How to wire 3-phase electric See wiring for 3-phase non-balanced water heater
Larger image	Example 3-phase distribution panel with 208-120 volt service/ ground wire shown Service voltage passes through meter and enters distribution panel. The 3 Hot wires connect to main breaker which energizes the 3 hot busbars where circuit breakers snap in. The Neutral wire means this panel has both 208V and 120V. 208 divided by √3 (1.732) = 120 volt 120 volt multiplied by √3 (1.732) = 208 volt Ordinary 3-pole, 2-pole and single-pole breakers are snapped onto the hot busbars. -The blue circuit breaker is 3-pole and feeds the Black, Red and Blue hot wires to a 3-phase 208 volt load like a motor. The Neutral and ground wires accompany the 3 Hot wires possibly for a control circuit that will control the motor. -The greenish circuit breaker is a 2-pole breaker that feeds 280 volt to an ordinary electric water heater. -The pink circuit breaker is a single-pole breaker that supplies 1 Hot wire that when combined with Neutral wire, supplies 120 volt to ordinary wall outlets etc.
Balanced loading: With any 3-phase service, it is important to 'balance' the breaker box so each of the 3 hot busbars draws equal power from the 3 transformers. If all usage was 3-wire 3-phase, then the problem would be simple, but when two-pole and single-pole breakers are used, the problem is more complex, For example at night, very little power would be needed for 120 volt outlets, but 208 volt water heater would still draw power. Suppose for example that one transformer must supply more power than the other two transformers, then the loading would not be balanced. Precise balanced loading is impossible as usage varies throughout the day, but overall when a breaker box is balanced as well as possible, then the unbalanced transformer is not the same transformer all the time. In the larger picture, if all commercial electric services on the grid are balanced as well as possible, then the amperage flowing on each of the three hot wires from the power plant will be nearly the same, which helps maintain reliable electric generation. Resource Basics of voltage imbalance "The common point [in a WYE] is called the neutral point. This point is often grounded at the supply for safety reasons. In practice, loads are not perfectly balanced and a fourth ‘neutral’ wire is used to carry the resultant current. The neutral conductor may be considerably smaller than the three main conductors, if allowed by local codes and standards." Source

Control circuits for 3-phase loads are always single phase

Buildings with 3-phase 208 volt WYE have a Neutral wire that can be combined with any one of the three hot wires to produce 120 volt, used to power ordinary 120Volt outlets.

The same 120 volt can be used as a control circuit for 3 phase loads such as motor etc. Illustration shows how a Hot wire can be pulled off the red wire, and then combined with Neutral to produce 120 volt.

1) Use 120 Volt timer etc.
2) Install 3-pole contactor or motor control contactor with 120 Volt coil
3) When timer turns ON, then 3-pole contactor turns ON, causing motor to turn ON.

Resource and diagrams:
How to wire 3-phase timer
How to wire Tork DTU40 timer

Larger image

Example single-pole breaker in 3-phase panel
Color added for illustration

Typical Hot wires used for 3-phase WYE in the US are color-coded Black-Red-Blue. High Leg Delta uses Black Black and Orange, with Orange for the high leg.

Note how a 3-pole breaker would snap down over all 3 Hot busbars, while a 2-pole breaker would snap down over 2 Hot busbars, and single breaker snap over one Hot busbar

Single-phase can be drawn by pulling one wire from a single breaker, or one wire from a 3-pole breaker or 2-pole breaker.

3Ø means 3-phase

Illustration shows wiring for twist lock and straight-blade outlets and connectors

Dual electrical ratings 208-240
Each appliance and electrical device has a rating plate that shows the acceptable voltage that will work with the device. For example, check label on ordinary electric water heater, and it shows 208 or 240 volt.

Many single-phase household electrical devices are made for dual voltages, such as electric water heaters, some timers, ovens, tankless water heaters etc are rated 208 or 240 volt.
Connecting to 208 volt usually means running at slightly lower power output, but otherwise you can connect either voltage and it will function as expected.

Dual voltage allows the appliance to be installed in a residential household that has 240 volt service, or installed at a business or apartment building that has 208 volt service.

Duel electric ratings are not unique to 208-240 volt. Another common example is a troffer (commercial drop in light fixture) that is rated 120-277 volt.
The 480-277 volt service is common in commercial businesses, and the 277 volts is readily available for a troffer by using 1 Hot and a Neutral.
If a commercial building has 208 volt service, then 120 volt is available for the troffer, but 277 volt is not available unless a small on-site transformer is installed.
Because 120 volt is not as efficient as higher voltages like 277 volt, then a building that has 208 volt service would use 208 volt lighting, or install a buck boost transformer and convert 208 volt to more efficient 240-277 volts for lighting.

Another example of dual voltages comes from motors that are rated 120 or 240 volt. The difference is the 120-240 volt motor requires rewiring, while 240-208 water heater and 120-277 troffer require no wiring changes if either voltage is used.

-Typical buildings, businesses and factories receive 3 phase electric power that is derived from 3 sets of transformer coils. Residential homes receive single phase power derived from one set of transformer coils.
Resource
Difference between single-phase and 3-phase

Water heaters work with any voltage not just 240-208
Appliances with a motor or circuit board that are connected to a voltage other than what shows on label, can burn up immediately.

480 volt element

Ordinary electric water heaters are different.
As long as you change the element to match the voltage, they will work with any voltage, 120, 208, 240, 277, 480 volt AC ... or 12-24-48 volt DC etc.
Note that voltage and wattage is printed on end of each element. The single-phase element shown to right is rated 4000 watts at 480 volt, and 3000 watts at 415 volt. This element would be used on a 3-phase balanced or unbalanced commercial water heater. Resource: 3-phase water heater
Note that 480-415 volt element would be found in a commercial electric water heater because houses receive only 120-240 single phase service ... houses do not have other voltages available such as 208 etc.
480-277 WYE and 240-415-480 volt High Leg Delta are both standard voltages found in 3-phase services.

The reason residential and commercial electric water heaters will work with any voltage is twofold: (a) the elements are resistive (like an incandescent light bulb) and (b) the thermostats are mechanical.

If 240 volt 4500 watt water heater is connected to 480 volts without changing element, then the element will burn out instantly because incoming voltage is higher than voltage rating on element.
If the elements are changed to 480 Volt rating and then connected to 480 volt, then the water heater will function correctly without needing to change thermostats. Ordinary electric water heater thermostats are mechanical bi-metal switches that are rated for any voltage up to 480 volt. Resource: Element specifications
FYI: To meet code the water heater label located on side of tank must be changed if different voltage elements are installed.
Resources:
How to replace element
Figure volts amps watts for water heater
Connect water heater to 120 volt
Connect water heater to generator
How to wire thermostats
Convert AC water heater to DC
Electric water heater voltage conversion pdf

Elements are made for 208-240 and 208 volt
Residential water heater elements are rated 208-240
There are also elements rated for 208 volt
Buy: 208 volt:
2000 watt 208 volt
208 volt elements

Buy: 208-240 volt:
2500 watt
3500 watt
4500 watt
5500 watt
Resources:
More about elements
Figure volts amps watts for water heater

3 phase water heaters
DPDT timers for any voltage
T100 series timers

What is 3-phase?
3-phase is generated at the power plant. It is more efficient than single-phase household voltages, but requires more wiring.
In a single-phase application, there are two wires and each device requires both wires to complete the circuit.
With 3-phase, each circuit requires 3 wires. When power is switched on-off, the switch turns off all three wires.

Consider another perspective:
120 volt single phase is like a two legged bicycle without pedal straps. You can push the pedal downward, but the upward stroke provides no power.
240 volt single phase is like a bicycle with pedal straps, so while one pedal is pushing down, the upward stroke is being lifted. Result: 240 delivers more power and efficiency than 120.
The limitation with single-phase 120-240 is when both pedals are at the top and bottom of the stroke, you get no power.
3-phase is different.
3-phase is like a 3-legged bicycle (if such a thing existed) where the pedals are each 60° apart so no pedals are at the top and bottom at same time. Result the average power is greater than single phase.
Resource:
What is 3-phase: power plant to end user
Difference between single-phase and 3-phase

Commercial 3-phase and residential single-phase:

Commercial 3-phase is much different than residential single phase.
Commercial 3-phase requires 3 transformers and is available in many different voltages, including 208 volt, and can be wired a variety of different ways including 3-phase or single phase.

Meanwhile residential single phase requires one transformer, and the secondary will produce 120-240 volt only. No other voltages are available for homes, just 120-240 volt.
How it happens: The single transformer receives one 7200 volt Hot wire and a Neutral off the three-phase distribution line, as seen in illustration.
The transformer has a 30:1 turns ratio that converts 7200 volt Hot into 240 volt on the secondary coil. The Neutral is taken from center of the secondary coil, and always produces half voltage or 120 volt.
Residential 120-240 single phase is much simpler to wire than 3-phase, using just two wires to complete each circuit. Moreover the 120-240 single transformer service has 120 volt readily available for outlets, lights, small appliances etc.

Why don't homes have 208 volt?
Homes have a single-transformer service. If a single transformer is used to produce 208 volt on the secondary side so that a home can have 208 volt, then the secondary coil would not have 120 volts available for plugs and outlets.
Why? Remember the Neutral comes off center point of the 208 volt secondary coil, but the center point, or half way point, or center tap always produces half voltage. This means 208 divided by half equals 104 volts, but not 120 volt. See single transformer

This also means if you live in a condo, or housing community, or high rise that has 208-120 volt service, then we know the voltage must come from a 3-transformer service, or 3-phase service.
Resources:
Difference between single-phase and 3-phase
Difference between WYE and Delta
Transformer configurations
Neutral currents in 3-phase WYE .pdf

Basic household wiring
What is 3-phase
How to wire 3-phase
Difference between single-phase and 3-phase
Difference between delta and wye
Identify transformer wiring

How to calculate the voltage for WYE
Test Hot to ground = voltage
Test Hot to Neutral voltage multiplied by √3 (1.7333) = Hot to Hot voltage
Test Hot to Hot voltage divided by √3 = Hot to Neutral voltage
Calculations assume balanced voltage across all three lines

208 Volt 3-wire delta
3 Phase 3 wire 208 No Neutral

The content on this page has avoided mention of 3-transformer, 3-wire, 3-phase 208 volt Delta, with no Neutral wire.
This configuration would be the result of 3 small transformers, or a 3-phase service used for a motor, like a sewage pump etc, but not the main service at occupied commercial building. Why? Because it can only deliver 3-phase 208 volt, but not 120 volt.

There cannot be a Neutral for this configuration because of the math of electricity.
The formula for a Neutral voltage would be 1/2 voltage (208 divided by 2) x √3 (1.732) ... equals 180 Volt which is not a standard voltage.

Resource:
How to identify transformer wiring
Transformer resources
How to wire 3-phase
Distribution wiring diagrams

Elements

Contactors/ relays

Z-wave/ wifi

Multimeter Test for breaks in wire/ Test for voltage Most appliance require 80% rated voltage to function correctly Buy Analog multimeter Multimeters at Amazon Klein multimeter Electric testers at Amazon Clampmeter for testing amp flow on line Resource: How to test and replace element How to test thermocouple Element tests for 120 volts How to test wire	Safety when testing wires: Never touch wet or previously flooded appliance. Never stand on wet surface when working on electric. Never stand on bare soil, put down dry boards. Tape tester leads to wood sticks to keep hands away from power. Use non-contact voltage tester before touching wires. Never touch or lean into any made of metal. Remove metal objects from pockets. Do not use oxygen or fuel accelerants in same room as electrical repairs Resource: Basic house wiring	Non-contact voltage tester Test for power without touching connectors NEVER assume power is OFF Buy: Non-contact voltage tester Amazon Electric testers at Amazon Resource: How to test electric power is off
120 volt 15 amp devices including GFCI, timers, switches, plugs, wifi controls etc can be installed on 15 or 20 amp breaker. 120 volt GFCI, outlet, receptacle that is rated 20 amp can be installed on 20 amp breaker only, but NOT on 15 amp breaker. Buy 15 amp GFCI 20 amp GFCI	Buy Basic electric book Home plumbing/ electrical codes Or learn about basic household electricity... use and search my site/ Resource Safe electric wiring Basic house wiring	Use outlet tester to check for correct wiring on any 120 volt straight-blade outlet. Buy: Klein testers Outlet tester Circuit breaker finder Electric usage monitor
Non metallic flexible cables must carry ground wire, but do not have hazard of short circuit causing injury from shock. Armored steel cable can be used as a grounded connection, and will protect wires from damage. Metal can be energized from an insulation failure. All conduit ...metal, plastic ... flexible and rigid ... must be attached to structure, and attached to enclosures, boxes. Movement, damage and deterioration are major cause of electrical failure. Buy: Non-metallic flexible conduit Power whip Armored cable Southwire armored cable cutter Pull boxes	Electrical tools must be insulated. Always best to disconnect power, but insulation failure, lack of proper grounding, grounded neutral, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems still pose a risk to anyone working on electric power ... even when breaker is off. Buy: Electrician tools kits KLEIN TOOLS Tools kits IRWIN tools KNIPEX	Connect wire to screw terminal Use only 600 volt solid copper wire. Do not use stranded wire or extension cord. Do not use solder anywhere on residential 120-240 volt wiring. Attach electric installation to structure. Tighten screws very tight against wire. Buy: NEC books Dewalt plumbing/ electrical codes Basic electric book National electric code guide/ illustrated Resources: How to twist wire How to select and install twist-on wire connectors
Weatherproof lever switch on outdoor lights Safely operate outdoor toggle switch Replaces outdoor cover Install over top of ordinary switch Works with single-pole, double-pole, 3PST, 3-way, 4-way switches etc Use weatherproof box for outdoor Can be used indoor or outdoor Buy: Best choice: Cantex lever switch Outdoor lever switches at Amazon Lever switches Resource Cantex-toggle-switch-covers.pdf Cantex-PVC-junction-boxes.pdf	Terminals Buy: Crimping tool kit Blue for 16-14 wire Yellow for 12-10 wire Ratcheting Crimper Resource: How to install terminal	Push-on wire connectors in place of twist-on connectors Buy: Push on wire connectors Amazon Red 3P connector for 10-14 gauge wire Lever connectors for stranded wire at Amazon
Use nipper instead of pliers or screwdriver for removing staples (and nails). Do not damage cable or wires inside cable. Code -Cable SHALL BE secured without damage to the outer covering. NEC sec. 336-15 Buy End cutting nippers at Amazon	When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistances on wire and creates weak point. Buy tools: Wire strippers at Amazon Linesman pliers Pro linesman plier Needle nose pliers End cutting nippers at Amazon	6" Pull box Junction boxes for conduit and wiring Buy: Bud industries 6x6x4 best value/ no KO Raco 6x6x4 metal pull box Wiegman 6x6x4 pull box Hoffman 6x6x4 pull box Adamax raintight enclosure Raintight 6x6x4 box Pull boxes Buy: Pull boxes Polycarbonite boxes Resource: Enclosures and boxes

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Terminals

Push-on wire connectors in place of twist-on connectors