Note: Whilst this is reply is not directly metric related, I do refer to
American Wire Gauge and mm²
I = P/V where I is Amps, P is Power & V is Volts.
The 240 volt laundry product described would have a dedicated outlet with a unique pin configuration. In Australia a typical clothes drier would be rated at 2400 watts and restricted to drawing current of 10 amps on a general purpose outlet. Less common, higher wattage clothes driers in Australia would require a dedicated 15 amp or 20 amp 240 volt circuit. The size of cable used to supply these circuits may be as small as 2.5 mm². US clothes driers are commonly rated as high as 5000 watts and they would typically draw a current of around 20 amps. 120 volts would not be practical for this size of clothes dryer as the running current could be high as 40 amps and this would require very large conductors and starting currents.
As a note: As an
Electrician I have connected one of these 24O volt US clothes driers for some US
citizens that migrated here. I still required a 240/120 volt step down
transformer to control aspects of the drier, such as the light inside the drum
and the motor that rotated it. (Australians in dry climates
typically use clothes lines located outside in the Sun rather than a
clothes drier.)
Article 220-18 Electric Clothes Dryers -
Dwelling Units(s). The load for household electric clothes driers in a
dwelling unit shall be 5000 watts (volt-amperes) or the name plate rating,
whichever is larger, for each dryer served.
Reference: United States
'The National Electrical Code 1987 Handbook'
The typical cable sizes available here are 1.0 mm², 1.5 mm², 2.5 mm², 4 mm², 6 mm², 10 mm², 16 mm²... (16 mm² is the common size providing the 240 volt, 50 hertz, 80 amp residential service to homes in either single phase or three phase).
The typical cable sizes available here are 1.0 mm², 1.5 mm², 2.5 mm², 4 mm², 6 mm², 10 mm², 16 mm²... (16 mm² is the common size providing the 240 volt, 50 hertz, 80 amp residential service to homes in either single phase or three phase).
Australia Minimum size conductor
for 240 volt circuits.
1.0 mm² 10 amp for light
circuits = 2400 VA (Watts = Volts x Amps x power
factor)
1.5 mm² 16 amp for
light circuits = 3840 VA.
2.5 mm² 20 amp multiple power
outlet circuits = 4800 VA.
4 mm² 20 amp power
outlets, but it is used for long runs due to volt
drop.
6 mm² 25
amp eg. ranges and
ovens.
USA Minium size
conductor for 120 volt circuits.
18 AWG (0.82 mm²) 6 amp circuits = 720
VA
16 AWG (1.31 mm²) 8 amp circuits = 960
VA
14 AWG (2.08 mm²) 17 amp circuits = 2040
VA
12 AWG (3.31 mm²) 23 amp circuits = 2760
VA
10 AWG (5.26 mm²) 28 amp circuits = 3360 VA
Reference: Article
402 - Table 402-5 United States
'The National Electrical Code 1987 Handbook'
Australian and
European systems
use 220 - 240 volts at 50
hertz, and as such we can use half the size of the
conductors the USA requires to supply the same load at 120
volts.
The USA uses 120
volts nominal at 60 hertz for general fixtures (eg washing machines, TVs. etc.), and uses 240
volts nominal at 60 hertz
for higher loaded appliances (eg clothes
driers and large air-conditioners). I have been
informed that while 120 volts is safer than 240 volts in the event of an electrocution, it can be the cause of more electrical fires that
begin due to the higher current being
drawn on faulty conductors or
joints.
If any one has ever shorted the wires on a 12 volt car battery,
the effects of much higher currents are violently
demonstrated.
The air-conditioner in my home is rated at 240 volts and 15 amps at a power factor of 0.7. This is the maximum sized unit allowed in Australia on a single
phase. Larger units must
be connected to a three phase
supply, which is due to starting
currents that can be several times higher
than the running current. Each of the phases to neutral is 240 volts at 50 Hertz. Between any two phases is 415
volts at 50 Hertz.
A single phase unit in the United States
is permitted to draw up to
40 running amps. I
presume this is most likely due to the complexity involved
in the supply of three
phases to the suburban home.
Article 440-62 states that the branch circuit for an
air-conditioner may not be more than 40 amperes and 250 volts, single
phase.
Reference: United States 'The National Electrical Code 1987
Handbook'
For an explanation
on the US power
distribution to homes go to http://www.howstuffworks.com/power.htm
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf Of Joseph B. Reid
Sent: Friday, 24 January 2003 04:38
To: U.S. Metric Association
Subject: [USMA:24573] Re: Power
>John Nichols asked in USMA 24572:
>
>I realize this is off list but why is the US 110 Volts and yet I can
>get 220 - 240 for the laundry products.
>
Three wires are brought into the house. The central wire is neutral.
The other two carry 115 volts alternating and in antiphase. The two
live wires provide 230 V between them. There is 115 V between a
phase line and the neutral line..
--
Joseph B. Reid
17 Glebe Road West
Toronto M5P 1C8 Telephone 416-486-6071
