Three-phase electric power: Household distribution

In summary, In Switzerland, it's quite common that some washing machines, dishwashers or electric stoves use three-phase power. So there's usually a three-phase plug in the kitchen and in the laundry room. In the UK houses normally only have one phase. A few houses have a three phase supply to a workshop for power tools (eg wood working). A few have a three phase supply if they have a large solar PV array (>4kw). In other European countries i think they sometimes have three phase supplies to specific appliances such as cookers and electric heaters, with all other sockets on one phase. Its usually considered dangerous to have a situation where there are single phase sockets on different phases in close proximity.
  • #1
greypilgrim
538
36
Hi.

How is three-phase electric power distributed in a household with mainly single-phase power plugs? Do they just connect a phase at random to every plug?

As far as I understood, it's best if all three phases deliver the same current, since then neutral cancels. Do electricians take into account which power plugs normally are in use simultaneously?
 
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  • #2
greypilgrim said:
Hi.

How is three-phase electric power distributed in a household with mainly single-phase power plugs? Do they just connect a phase at random to every plug?

As far as I understood, it's best if all three phases deliver the same current, since then neutral cancels. Do electricians take into account which power plugs normally are in use simultaneously?
Where have you seen households with 3-phase power connections to the Grid?

It's common to have 2-phase connections in US households, with 220V across the outer Lines and two 110V phases between each Line and the single Neutral. And yes, you try to balance the two 110V phase loadings...
 
  • #3
greypilgrim said:
Do they just connect a phase at random to every plug?

As far as I understood, it's best if all three phases deliver the same current, since then neutral cancels. Do electricians take into account which power plugs normally are in use simultaneously?
Yes, but not exactly random, because...yes.

It also isn't very critical for the phases in a single house to be balanced. But on a street or apartment building, yes.
 
  • #4
berkeman said:
Where have you seen households with 3-phase power connections to the Grid?
In Switzerland, it's quite common that some washing machines, dishwashers or electric stoves use three-phase power. So there's usually a three-phase plug in the kitchen and in the laundry room.
 
  • #5
In the UK houses normally only have one phase. A few houses have a three phase supply to a workshop for power tools (eg wood working). A few have a three phase supply if they have a large solar PV array (>4kw).

In other European countries i think they sometimes have three phase supplies to specific appliances such as cookers and electric heaters, with all other sockets on one phase.

Its usually considered dangerous to have a situation where there are single phase sockets on different phases in close proximity. For example i think different phases can be used on different floors of a building but not on the same floor.
 
  • #6
At first, in Europe, the standard for new building-usually- is 3 phases household supply-3*400/sqrt(3) 25[40] A and neutral and earthing [grounding].
The 3 phases are mainly for HVAC [about 4 kW] and all other equipment as stove, washing machine, dryers, receptacles and other are single phase.
The panel is provided with MCB and/or MCCB as required.
The utility panel is provided with single phase 40 A [or more as required] fuses and neutral. The neutral-unprotected-is grounded only in one point.
The neutral may convey up to one phase rated current and it is, usually, unbalanced system. See IEC 60364-1-for instance.
 

Related to Three-phase electric power: Household distribution

1. What is three-phase electric power?

Three-phase electric power is a type of electrical power distribution that uses three alternating currents that are offset by 120 degrees. This allows for a more efficient and balanced distribution of electrical energy, compared to single-phase power.

2. How is three-phase electric power distributed in households?

In households, three-phase electric power is typically converted into single-phase power through a transformer. The single-phase power is then distributed through a main panel and subpanels to various outlets and appliances in the house.

3. What are the advantages of using three-phase electric power in households?

One of the main advantages of using three-phase electric power in households is that it allows for a more balanced distribution of power, resulting in a more stable and efficient energy supply. It also allows for higher power capacities, making it suitable for households with high electricity demands.

4. Are there any safety concerns with three-phase electric power in households?

There may be safety concerns with three-phase electric power if the system is not properly installed or maintained. However, as long as the wiring and equipment are up to code and regularly inspected, three-phase power is generally considered safe for household use.

5. Can three-phase electric power be used for renewable energy sources?

Yes, three-phase electric power can be used for renewable energy sources such as solar or wind power. These sources can be converted into three-phase power through inverters, which can then be distributed to households for use.

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