How do I esplain

 

Got into a argument at the pub the other day. LOL
According to the guy I was arguing with he says that if I am going to
use resistive heating that I should use 220vac instead of 110vac because
I will get twice the heat (BTU) for half the power reading on my metor?
I need something to print off to esplain to him how 220 works....221
whats the diff right.

 

If you have 1200 watts of heat (baseboard or whatever)
this will take 10 amperes of current at 120 volts.

This will also take 5 amperes at 240 volts.

Multiplying your volts times your amperes (current)
will yield watts or the heat you will get from your
heater.

i.e.: 5 amps X 240 volts = 1200 watts
     10 amps X 120 volts = 1200 watts

So your friend is correct but a little confused. Yes,
the heater will take half the amperes at 240 volts but
the power (watts) will be the same in either case and
that is what your meter will see either method.

Now for the clincher. At 120 volts your heating will
take twice the current (amps) and that takes twice the
copper conductors (cross section) to get it there. Much
heavier wire needs to be run and that costs bucks.

Good luck



if I am going to

instead of 110vac because

reading on my metor?

220 works....221

 

In the simplest look, the amount of BTU you get from a given heater
should be the same, given the watts of electricity consumed.  However,
that said, you should also bear in mind that some power meters don't
handle high current on one side of the 240 volt line very well.  This is
primarily due to the electric company providing and metering at 240
volts. I've seen a few that will meter a 10 ampere load on 120 volts
(one side only) as if it were a 10 ampere load for the entire 240 volt
service, unless there is a corresponding load on the other side of the
line.  Not all meters have this problem, but there are some out there
that still do.  It's not exactly in the best interests of the power
company to replace these meters, as they are money makers in the event
you present an unbalanced load.

Thus, if you have a single heater on one side of the line, or two
heaters on the two sides of the line (neutral being the boundary between
the two 120 volt lines) and one heater runs more than the other, the net
cost could be higher than if you were using 240 volt heaters of the same
wattage.

Another problem you can run into is load imbalance affecting the actual
voltages you see on each side of the line.  In extreme
circumstances, putting a large 120 volt  load on one side of the 240
volt supply will "float" the neutral, moving it considerably away from
nominal 0 volts.  This can cause a lower net voltage on the heavily
loaded side and a higher net voltage on the lightly loaded side.  (This
effect is especially seen in cases where "daisy chain" wiring is the
norm, and there are one or more wirenut connections that are less than
perfect.)  It's not unusual for older homes to see 100 volts on a heavy
loaded side, while there is 140 volts on the lightly loaded side.  This
can play havoc with all sorts of devices on the higher voltage side of
the line.  Unfortunately, some "marginally wired"  newer homes have as
much problem with this as older homes, because some of the wiring is
done with 4 wires in a sheath, not two separate, three wire sheaths to
different circuits.  With the 4 wire sheath, there are two "hot" wires,
one neutral, and one safety ground.  The assumption is that the two hot
lines will have equal currents and the net current in the neutral will
be near zero, or at least the maximum offset will be within the current
carrying capability of the neutral wire. Unfortunately, this is not
always the case, even if correctly configured.  Also, if this sort of
sheathed cable is incorrectly connected (both hot wires on the same side
of the  line) it can present a significant hazard if both circuits are
heavily loaded.   With two separate sheathed cables, each circuit has a
dedicated  hot, neutral and safety ground, each of which is connected
directly to the distribution panel and not shared with any other
circuits.

During the initial construction, the loads are supposed to be
distributed equally on both sides of the line to present as balanced a
load as possible on the 240 volt service.  This limits the potential
exposure to running heavy loads on one side of the line compared to the
other.  Unfortunately, not all electricians care enough to actually
balance the expected loads, and many homeowners add things like portable
120 volt space heaters that radically affect this possible balance.

Most baseboard heaters are 240 volts, while portable plug-in units tend
to be 120 volts (at least in the US).
As already mentioned by a previous poster, running wire to 240 volt
heaters is less expensive (per watt) than 120 volt heaters.  If you are
considering new wiring to handle electrical heaters, you should at least
consider 240 volt ones.  If, on the other hand, you are using portable
units, you should be very careful to make sure the ones you purchase
have tip sensors (and shut off when the unit is disturbed or tipped
over), and at least try to balance the loads on opposite sides of the
240 volt line so you don't end up paying even more than you normally
would for electric heat.  Also, you should be aware that most baseboard
heaters run at a lower temperature (at least on a per square inch
basis), and are inherently more safe (especially when unattended by a
careful adult) than most portables, which require minimum 36" spacing
from flammable objects...

For my money, I'd use 240 volt heaters and avoid the potential problems
with balancing the 120 volt ones.

--Rick


SolarFlaire wrote:

 

Not in Canada you won't see a meter do that. I have
seen all the approvals.

Can you state a meter type that can do this?

To aid in your confusion, the run-of-the-mill domestic
meter has only one potential coil (240V) and two "half"
current coils, one on each leg. Yes, it's to make it
cheaper.

Yes on a severely unbalanced ***VOLTAGE*** system there
can be unfair metering. One leg will meter with it's
current against half the total voltage. If you are
loading the low voltage leg then you are getting an
error against you.

This is only can only be slight (less than about 2%)
without wires and devices burning up, or bad
connections causing same usually.

A balanced electrical system is always good as your
neutral may not be sized to handle the load the line
legs are.

Now, on some multi unit complexes there is such a thing
as a "network" meter where three phase power is
supplied and only two legs and a neutral is supplied
each unit. This can save on copper. The voltages are
now at 120 degrees to each other and the voltages would
classically be 125, 125 and 216 vac. A phase to phase
load requiring 10 amps at 216 volts would consume 2160
watts (assuming resistive) the meter would see 10amps x
120 volts in each leg and although it would appear to
add up to 2400 watts there is a 30 degree phase angle
in each leg so the meter would see 120volts x 10amps x
cos(30deg) = 1080 watts in each leg for a total of 2160
watts!

Now VA demand customers get ripped as there are
differences between arithmetic summation of va and
phasor addition of va. One favours the utility and one
favours the customer. Domestic users never have to
worry about this problem.

Hope that confuses the shit out of ya....LOL



a given heater

consumed.  However,

power meters don't

very well.  This is

metering at 240

load on 120 volts

the entire 240 volt

other side of the

are some out there

interests of the power

makers in the event

line, or two

the boundary between

the other, the net

heaters of the same

affecting the actual

extreme

side of the 240

considerably away from

on the heavily

loaded side.  (This

chain" wiring is the

that are less than

100 volts on a heavy

loaded side.  This

higher voltage side of

newer homes have as

of the wiring is

three wire sheaths to

are two "hot" wires,

is that the two hot

the neutral will

within the current

Unfortunately, this is not

if this sort of

wires on the same side

both circuits are

each circuit has a

which is connected

with any other

supposed to be

present as balanced a

limits the potential

line compared to the

enough to actually

things like portable

possible balance.

plug-in units tend

wire to 240 volt

heaters.  If you are

you should at least

are using portable

ones you purchase

disturbed or tipped

opposite sides of the

than you normally

that most baseboard

square inch

unattended by a

minimum 36" spacing

potential problems

whatever)

 

SolarFlaire wrote: