208VAC issue

[electrofelon]

Do they even make resi 208 volt clothes dryers and residential ovens?

People always mention this, "get 208 appliances or you will have less output". I looked a while a ago and could not find any residential ranges, dryers, or water heaters that are available in a 208 version with same output as 240. Maybe if you are ordering a high rise worth you can get them the way you want.

 

[mbrooke]

People always mention this, "get 208 appliances or you will have less output". I looked a while a ago and could not find any residential ranges, dryers, or water heaters that are available in a 208 version with same output as 240. Maybe if you are ordering a high rise worth you can get them the way you want.

You can get 208 volt water heaters but to my knowledge I don't know of Whirlpool, GE or Frigidaire offering 208 volt only stoves/dryers/convec micros but I could be wrong on that.

 

[kwired]

With a dryer it is going to take longer to reach thermal cut off temp. Once that temp is reached it won't be too difficult to maintain. That temp may not be reached while clothes are still pretty wet so could still increase overall cycle time for otherwise the same task.

Oven, you want to cook something at 350 degrees for 1 hour, that oven is going to take longer to preheat at 208 volts, but will maintain the 350 degrees as long as you don't open the door every couple minutes or so.

cook top, will take longer to raise a pot of water to boiling temp or other similar initial warm up. Will likely apply "maintenance heat" fairly successfully once target temp is reached. Some those "smooth top" cooktops don't heat as fast as conventional elements anyway and take longer time to heat even on 240 volts. This to protect the top from thermal shock more than anything.

 

[electrofelon]

You can get 208 volt water heaters but to my knowledge I don't know of Whirlpool, GE or Frigidaire offering 208 volt only stoves/dryers/convec micros but I could be wrong on that.

The better water heaters Are often 5500 watts at 240, which is 4130 @ 208

 

[mbrooke]

With a dryer it is going to take longer to reach thermal cut off temp. Once that temp is reached it won't be too difficult to maintain. That temp may not be reached while clothes are still pretty wet so could still increase overall cycle time for otherwise the same task.

Oven, you want to cook something at 350 degrees for 1 hour, that oven is going to take longer to preheat at 208 volts, but will maintain the 350 degrees as long as you don't open the door every couple minutes or so.

cook top, will take longer to raise a pot of water to boiling temp or other similar initial warm up. Will likely apply "maintenance heat" fairly successfully once target temp is reached. Some those "smooth top" cooktops don't heat as fast as conventional elements anyway and take longer time to heat even on 240 volts. This to protect the top from thermal shock more than anything.

Yup and yup. And if you want my honest opinion the average person typically can not tell the difference. Perhaps for broiling but still I don't read or hear about many complaints if any.

FWIW, I've found that ovens on a 240 volt supply take longer to pre-heat as they age. Eventually the element burns outs as I've discovered.


There is one big plus to 208 volts that appliance repair man have told me: the heating elements never burn out on stoves and dryerss .

 

[mbrooke]

The better water heaters Are often 5500 watts at 240, which is 4130 @ 208

Yup. If I read it right code in some cases requires a 25 amp breaker on 208.

 

[LarryFine]

Thank you all for your responses. I don’t know if this can be answered in an open forum, but how do I get voltage at L1 to ground and L2 to ground but not between the two lines? I guess I don’t understand how I can lose a leg, but still show voltage? Are both wires landing on the same side of the breaker?

Best explanation: Turn off all of the 2-pole breakers, measure again, and tell us what you observe about half of the 120v circuits..

 

[kwired]

Yup. If I read it right code in some cases requires a 25 amp breaker on 208.

Where you get that from? It draws nearly the same amps as 4500 watts does @ 240 which is allowed to be on a 30 even though 25 is next size higher after factoring 125%. I believe this kind of load is allowed to be on circuit of up to 150% of rated amps, which is why it is common to see 30 amp breaker for 4500 watt at 240 even though 25 will work, either case 10 AWG conductor is still needed.

 

[mbrooke]

Where you get that from? It draws nearly the same amps as 4500 watts does @ 240 which is allowed to be on a 30 even though 25 is next size higher after factoring 125%. I believe this kind of load is allowed to be on circuit of up to 150% of rated amps, which is why it is common to see 30 amp breaker for 4500 watt at 240 even though 25 will work, either case 10 AWG conductor is still needed.

Well, if we consider a water heater an appliance

(E) Single Non–Motor-Operated Appliance. If the branch
circuit supplies a single non–motor-operated appliance, the
rating of overcurrent protection shall comply with the following:

(1) Not exceed that marked on the appliance.

(2) Not exceed 20 amperes if the overcurrent protection
rating is not marked and the appliance is rated
13.3 amperes or less; or

(3) Not exceed 150 percent of the appliance rated current if
the overcurrent protection rating is not marked and the
appliance is rated over 13.3 amperes. Where 150 percent
of the appliance rating does not correspond to a standard
overcurrent device ampere rating, the next higher standard
rating shall be permitted.

 

[kwired]

Well, if we consider a water heater an appliance

What did you think it was before you decided it might be an appliance?

 

[mbrooke]

What did you think it was before you decided it might be an appliance?

Resistance boiler In some parts of the world hot water storage tanks are called "boilers"

 

[Ainsley Whyte]

I would call it an open circuit on one of the two incoming lines.

Totally agree I remember just recently I had a similar problem, the supply 220VAC was send to a double pole switch, where one pole was open circuit

 

[kwired]

Resistance boiler In some parts of the world hot water storage tanks are called "boilers"

I don't know mechanical codes but pretty sure temp and pressure, and maybe factored in is how fast temp or pressure can develop come into play on what those codes call a boiler, a unit intended for simple domestic hot water normally isn't a boiler.

 

[kwired]

Best explanation: Turn off all of the 2-pole breakers, measure again, and tell us what you observe about half of the 120v circuits..

Or measure voltages on a 240 volt air conditioner unit that has one of those contactors that only switches one pole and figure out why all four terminals read 120 volts to ground when that one pole is in open state.

 

[Hv&Lv]

One other thing I have seen if it’s a new installation.
same leg wired to both sides..
New because it usually gets fixed pretty quick

 

[hillbilly1]

One other thing I have seen if it’s a new installation.
same leg wired to both sides..
New because it usually gets fixed pretty quick

Wait to you get one that’s 480 to ground! I had a pylon sign that was that way, traced it back, and the contractor miss labeled the ground at the panel, and had it terminated to a breaker. The entire parking lot was hot! Even with all of the ground rods at the poles, the resistance was not low enough to trip the breaker.

 

[jap]

Best explanation: Turn off all of the 2-pole breakers, measure again, and tell us what you observe about half of the 120v circuits..

That's not the best explanation for him if he doesn't understand it.
Actually, that's a confusing explanation.
If he shuts off the 2p breaker feeding the unit he will read zero at the unit.

To the OP,
In very simple terms picture a 240v incandescent light bulb.
Power goes to the lamp on A phase through the filament and back on B phase to the panel.

2 different phases or "Legs" are in play in this scenario, thus both A and B phases or "Legs" are connected at the light bulb socket, you would read 240 volts at the socket, and, the bulb would be lit.

Now,
Picture taking the B phase return wire off of the 2 pole breaker at the panel.

The bulb goes out because it's lost it's 240v supply.
It is not designed to operate on only 120 volts.

In this scenario 120v travels from the panel on A phase to the socket "through the filament" and back on B phase to the panel, but you've taken the wire off of B phase at the panel.

Therefore, you've lost your 240v circuit and are dealing with only A phase from the panel through the filament and back to where you took it off.

If you take your meter and read the voltage at the socket you would read A phase only or 120v to ground on both the supply and return wires connected to the socket because you are reading through the filament on the bulb.
But,
You would read "Zero" between the 2 wires because B phase was disconnected and your taking a reading on only the A phase conductor by itself.



JAP>

 

[kwired]

That's not the best explanation for him if he doesn't understand it.
Actually, that's a confusing explanation.
If he shuts off the 2p breaker feeding the unit he will read zero at the unit.

To the OP,
In very simple terms picture a 240v incandescent light bulb.
Power goes to the lamp on A phase through the filament and back on B phase to the panel.

2 different phases or "Legs" are in play in this scenario, thus both A and B phases or "Legs" are connected at the light bulb socket, you would read 240 volts at the socket, and, the bulb would be lit.

Now,
Picture taking the B phase return wire off of the 2 pole breaker at the panel.

The bulb goes out because it's lost it's 240v supply.
It is not designed to operate on only 120 volts.

In this scenario 120v travels from the panel on A phase to the socket "through the filament" and back on B phase to the panel, but you've taken the wire off of B phase at the panel.

Therefore, you've lost your 240v circuit and are dealing with only A phase from the panel through the filament and back to where you took it off.

If you take your meter and read the voltage at the socket you would read A phase only or 120v to ground on both the supply and return wires connected to the socket because you are reading through the filament on the bulb.
But,
You would read "Zero" between the 2 wires because B phase was disconnected and your taking a reading on only the A phase conductor by itself.



JAP>

You are not trying to operate it at 120 volts though, and if you did connect it to 120 it probably does light, just not as much as when 240 is applied.

How about you have 120 volt potential to ground on A conductor, the filament is nothing more than an extension of that conductor to the B side of the lamp - since B is not actually connected to the B supply conductor it basically also becomes extension of A. There is no voltage drop through the filament because there is no current flow.

Ohm's law has not been broken, just expected conditions have changed.

 

[jap]

You are not trying to operate it at 120 volts though, and if you did connect it to 120 it probably does light, just not as much as when 240 is applied.

How about you have 120 volt potential to ground on A conductor, the filament is nothing more than an extension of that conductor to the B side of the lamp - since B is not actually connected to the B supply conductor it basically also becomes extension of A. There is no voltage drop through the filament because there is no current flow.

Ohm's law has not been broken, just expected conditions have changed.

If he doesn't understand why he's getting the readings he's getting, I don't think he's going to understand your "potential to ground" or the "filament being an extension of the conductor" or the whole "voltage drop through the filament" things.

I admit the reference to the unit not operating at 120 volts was a mistake on my part seeing as how your actually dealing with an open circuit as Charlie stated and not an actual 120v circuit being applied to a 240v piece of equipment.

That comment was more a reference to his "120v to ground on both legs and nothing between them and the unit not working".

Even though very elementary, I think I helped him somewhat understand the reasons he was getting the readings he was getting.

JAP>

 

[kwired]

If he doesn't understand why he's getting the readings he's getting, I don't think he's going to understand your "potential to ground" or the "filament being an extension of the conductor" or the whole "voltage drop through the filament" things.

I admit the reference to the unit not operating at 120 volts was a mistake on my part seeing as how your actually dealing with an open circuit as Charlie stated and not an actual 120v circuit being applied to a 240v piece of equipment.

That comment was more a reference to his "120v to ground on both legs and nothing between them and the unit not working".

Even though very elementary, I think I helped him somewhat understand the reasons he was getting the readings he was getting.

JAP>

Might not get any of the explanations given without some illustrations, who knows? None of them were flat out wrong, but every one still could still be misunderstood.