220 or 240

[Halfathumb]

LOML wants a new heater for her greenhouse. It states 240. Is that the same as 220?

Thanks

Jim

[fredhargis]

LOML wants a new heater for her greenhouse. It states 240. Is that the same as 220?

Thanks

Jim

Yep, 240 is the correct designation. 220 (as I understand it) is a holdover from years gone by.

[TDKPE]

Yep, 240 is the correct designation. 220 (as I understand it) is a holdover from years gone by.

You understand it correctly, but I would add that it's decades, or even half-centuries gone by.

Halfathumb - most common loads will be rated 120V or 240V (look at any normal incandescent light bulb), except for motors and transformers and such, which will be 115V or 230V. That's the actual design voltage of the motor, and some voltage drop is built into that reduced design voltage, since motors are sensitive to voltage.

[KC]

Yep, 240 is the correct designation. 220 (as I understand it) is a holdover from years gone by.

I thought 230 was correct now.

[TDKPE]

I thought 230 was correct now.

115/200/230/460/575V is the NEMA standard voltage for motors and some other induction machines running on 120/208/240/480/600V nominal* systems, respectively.  That might be where the 230V figure came from.

The voltage requirements for US utilities is defined in the ANSI C84.1, which for normal conditions is defined as 120 and 240V +/-5%, as delivered to the service equipment (the first disconnect, usually the main panel).  An additional 5% is also in that standard, at the utilization equipment, and that same 5% is in the NEC, though that part isn’t code enforceable.  So in a nutshell, +5 to -10% means 126V [252V] to 108V [216V] at the load, under load, is considered acceptable for normal operation.

There is a wider margin in the ANSI, for short-term operation, but it’s not considered ‘standard’ and it’s expected that it will be corrected.

*Nominal, which means name (from the latin nominalis). It's the official designation for voltage in North America, and has been for a really long time now.

[Roly]

115/200/230/460/575V is the NEMA standard voltage for motors and some other induction machines running on 120/208/240/480/600V nominal systems, respectively.  That might be where the 230V figure came from.

The voltage requirements for US utilities is defined in the ANSI C84.1, which for normal conditions is defined as 120 and 240V +/-5%, as delivered to the service equipment (the first disconnect, usually the main panel).  An additional 5% is also in that standard, at the utilization equipment, and that same 5% is in the NEC, though that part isn’t code enforceable.  So in a nutshell, +5 to -10% means 126V [252V] to 108V [216V] at the load, under load, is considered acceptable for normal operation.

There is a wider margin in the ANSI, for short-term operation, but it’s not considered ‘standard’ and it’s expected that it will be corrected.

In the area I worked we set the automatic tap changers in the substations  to keep the voltage between 120 and 123 v, there were also settings for how far away the loads were.    We set the voltage center at 121.5 v and had a 3 volt band width.  For a 7200v distribution system a 60v change at the substation would change your voltage 1 volt.    Roly

[FireWood]

LOML wants a new heater for her greenhouse. It states 240. Is that the same as 220?

Thanks

Jim

[Kekonsetyk]

220 volt is the same difference as 240,

In some areas of the county (where you can get a cash advance on this page) it is 220 and some areas it can be 240, It is the same as saying 110 or 120 volts, in our area it is 117 volts, and 234 volts.
I am under the impression the newer installations are running more in the 120/240 range, if your voltage is above 120/240 or below 110/220 then your operating out of normal voltages.

as far as the heater, you will need to size the wire and breaker to the amps,

I am not familiar with a dryer that runs on 110 volts, (clothes dryer).

If the amps and such and (if it is a typo on the dryer, it is 220/240 volts) I can see no reason you could not use the outlet, for the heater.

[Z28Doug]

208, 220 and  230 volts generally refers to modern Delta-Wye transformer systems.  In the old school Delta-Delta 3-phase systems you had 240 volts, but it also came with a "wild leg" .  Seen in older machine shops and commercial bldgs.
  I remember corner grounding an old Delta-Delta system, gets interesting! Nowadays NEC won't allow it.