PDA

View Full Version : OT: 220v question



Tony Ennis
03-12-2011, 07:15 PM
a pal of mine is having trouble with his 220v dryer. It worked at his house this morning, and it does not work at his daughters house now.

The previous owner of his daughter's house did everything wrong or slipshod.

I'm suspecting his 220v isn't 200v. How can he verify that his power is correct? Each leg of the 220v when measured against ground should be 110v. What if he measures across both legs of the 220v with a volt meter?

He says the machine just hums when he turns it on. Sounds to me like the motor is fighting itself, if that is possible, like both sides of his 220v are actually the same phase.

He says it has a 220v breaker. I asked him to verify the box is of the 'alternating finger' type so the 220v breaker will do what you think.


Ideas?

recoilless
03-12-2011, 07:32 PM
a pal of mine is having trouble with his 220v dryer. It worked at his house this morning, and it does not work at his daughters house now.

The previous owner of his daughter's house did everything wrong or slipshod.

I'm suspecting his 220v isn't 200v. How can he verify that his power is correct? Each leg of the 220v when measured against ground should be 110v. What if he measures across both legs of the 220v with a volt meter?

He says the machine just hums when he turns it on. Sounds to me like the motor is fighting itself, if that is possible, like both sides of his 220v are actually the same phase.

He says it has a 220v breaker. I asked him to verify the box is of the 'alternating finger' type so the 220v breaker will do what you think.


Ideas?

Across the two hots, I'd suspect you would want to see 220/230/240v whatever that voltage may be.

Is he sure the dryer works? A lot of times these problems are of a very simple nature...loose connection, etc. If he can trace wire directly to breaker, it would be evident what the voltage is.

wierdscience
03-12-2011, 07:32 PM
Open the dryer door and make sure the drum turns by hand.I had one bounce out of kilter in a move once,a quick turn of the drum and it clunked back into groove.

A "Wiggy" will tell you alot about a circuit,they have them at Homedespot and Lowdown's-

http://www.google.com/products/catalog?hl=en&q=wiggy+voltage+tester&rlz=1W1ADFA_en&um=1&ie=UTF-8&cid=1007351579064271994&sa=X&ei=RBB8TcCcMqTH0QHqyJjgAw&ved=0CCkQ8wIwAA#

garagemark
03-12-2011, 07:49 PM
A volt meter across both hot legs should read 220-240 volts. Also check each leg to ground (in the ground pin) to insure a well grounded circuit. Almost all dryers use 110 volts for the controls, and have always used the ground as a neutral. All new installations are required by National Electric Code to be four wire now; two hot legs, a ground leg, and a neutral.

If the electric is verified to be 220-240 volts, properly grounded, then do what wierdscience has suggested, look for a mechanical bind.

Tony Ennis
03-12-2011, 08:50 PM
He's verified 220v across the hot legs and 110v from each hot to ground/neutral.

He took the dryer to a repair shop and it worked there.

He doesn't have a 4th wire/different ground/neutral. Is it possible the dryer won't work without a separate wire for each? I was under the assumption they were the same thing.

spkrman15
03-12-2011, 08:58 PM
You can have 110v to ground on both sides of the plug but NOT 220v. If the power is coming from the same leg in the pannel then you will only have 2 lines of 110v. Take your meter and check that you HAVE 220v from both sides of the plug. If you have 110v to ground, but nothing when you go across the the plug then the power is coming from the same leg. You also need the neutral from the pannel, as it lets the motor and controls run on 110v but the Heating element runs on 220v.

Good luck.

Rob :)

Ken_Shea
03-12-2011, 09:01 PM
Measure the voltage under load, see if it still reads 220V across both.

lakeside53
03-12-2011, 09:02 PM
If the dryer is set up for 4 wire, and you put it on a three wire circuit, you may have to bridge Neutral and Ground in the dryer. If it's applicable, there should be a circuit and adjustment procedure labeled in the back of the dryer.


Look for the stupid stuff - loose wires... bad connections. If the branch wires are aluminum, make sure you (or the prior guys) use anti-oxident paste on the terminals.

jack3140
03-12-2011, 09:39 PM
He's verified 220v across the hot legs and 110v from each hot to ground/neutral.

He took the dryer to a repair shop and it worked there.

He doesn't have a 4th wire/different ground/neutral. Is it possible the dryer won't work without a separate wire for each? I was under the assumption they were the same thing.
sounds to me like the plug in the box is defective

tdmidget
03-12-2011, 10:51 PM
Neutral and ground are most certainly not the same thing and not interchangeable. While a dryer or other machine might run using the ground as a neutral it would be very dangerous. If it does not run you may have an even more dangerous situation, no ground.

J Tiers
03-12-2011, 10:52 PM
sounds to me like the plug in the box is defective

You'd think......

if he has a different plug on the dryer NOW, in order to plug into the 4 wire system at the new place, ARE YOU SURE IT'S WIRED RIGHT?

if he didn't need to put a new plug on, double check the outlet, to be sure that things are on the pins they are supposed to be....

I keep thinking about that statement:

"The previous owner of his daughter's house did everything wrong or slipshod."

That sounds like a very possible cause of all this trouble.

The chassis could even be hot on the thing... I'd be VERY careful if the wiring is that bad......

Paul Alciatore
03-13-2011, 01:51 AM
If the wiring in the house is that suspect, I would run a wire to a known good ground and check the plug from that. Check to all three or four pins. Two (the hots) should show 110/115 Volts and the other one (ground) or two (ground and neutral) should show zero or just 1 or 2 Volts at most. If you have anything different, call an electrician.

And yes, do check across the two hots with a load in place. A couple of 110 Volt light bulbs wired in SERIES would do. Or the dryer itself. It should read 220 Volts under load.

Tony Ennis
03-13-2011, 09:38 AM
do check across the two hots with a load in place

What's the significance of checking it under load? What should it show?

MotorradMike
03-13-2011, 10:25 AM
What's the significance of checking it under load? What should it show?

It will show up a poor/corroded connection upstream of the test point.
I'm not sure it's a good idea to use the drier as a load though. if the motor is trying to start with low voltage you might damage it.

lakeside53
03-13-2011, 01:24 PM
Like I said earlier -if the wiring to the receptable box is aluminum, and the connections were made without anti-oxident, you can have a high resistance or loose connection. Putting it under load will show this. Same at the breaker end.


I pull the box and panel cover off, and check both ends.

ckelloug
03-13-2011, 03:28 PM
td,

There was an exception in the code based on saving copper for world war 2 that allowed dryers to be run using the neutral as ground. This is a special case exception to your comment. New installations as of a few years ago are no longer allowed to be done that way.

garagemark
03-13-2011, 07:13 PM
99% of our dryers do indeed use the ground as a neutral. If you have a three wire dryer cord and receptacle, your dryer is using the ground for a neutral.

This is a good link as to the old and the new:

http://www.ask-the-electrician.com/wiring-a-dryer-power-cord.html

Mark

tdmidget
03-13-2011, 08:10 PM
td,

There was an exception in the code based on saving copper for world war 2 that allowed dryers to be run using the neutral as ground. This is a special case exception to your comment. New installations as of a few years ago are no longer allowed to be done that way.

What? World War II? While many World War II clothes dryers did indeed use 3 wires, they were strung between poles in the backyard where the sun was prevalent.

J Tiers
03-13-2011, 10:22 PM
What? World War II? While many World War II clothes dryers did indeed use 3 wires, they were strung between poles in the backyard where the sun was prevalent.

And for 20 years after that, depending..... I didn't know anyone whose family had a dryer into the 1960s... you's always see washing on the line in dry weather.

In WW2 people would have (if they had had them) been told to turn off the indoor dryer and use the "outdoor dryer" as part of the war effort. But I doubt many if any did have them.

As for the dryer, if it works elsewhere and not there, then it is almost certainly a case of bad wiring. WHY bad, and WHERE bad, we have no way of guessing.

remember: "The previous owner of his daughter's house did everything wrong or slipshod."

ckelloug
03-14-2011, 11:39 AM
Maybe not an awesome reference, but here's a web site corroborating what I remembered reading about dryers:
http://www.myrv.us/electric/Pg/ground_wire.htm

bborr01
03-14-2011, 12:15 PM
Sounds like a loose wire to me.

I'd turn the breaker to that circuit off and check the connections for tightness. On the breakers, ground and inside the outlet.

You can get a reading of 220/240 volt with a meter and under load can be much less with a loose connection.

Brian

tdmidget
03-14-2011, 10:41 PM
I see. It says stoves and dryers. I suspect that it applied more to the few electric stoves than the dryer or two that might have existed. I was also surprised that there might be an epidemic of WWII appliances being installed in RVs.
Regardless of past practice, we know better now. To be safe rather than cheap, use 4 wires.

garagemark
03-15-2011, 06:55 AM
Not me. I'll stay with three wires until I build a new house. It's worked quite well for sixty or so years, and 99% of all US homes still use three wires. I think we'll all survive it.

MrSleepy
03-15-2011, 07:51 AM
Neutral and ground are most certainly not the same thing and not interchangeable.
While the terminology are not interchangeable...
In the UK most houses are provided with a phase and neutral...the earth being derived from the neutral at the incoming cable connection
The most common arrangement, TN-C-S (http://www.epanorama.net/documents/groundloop/earthing_arrangements.html) [Protective Multiple Earthing] Supply combines neutral and earth, but they are separated out in the installation.


Does the US have equivalents to these variations?.

Rob

J Tiers
03-15-2011, 08:49 AM
The by-far most common setup here seems to be like TN-C-S, where the neutral is carried along on the poles, and is earthed at every pole or every other one (always at transformers).

neutral is common to HV and LV (but, as mentioned, is earthed)

Neutral and hot(s) are brought in to the service, where neutral is again earthed, and a "equipment grounding conductor", which is your green/yellow conductor, is run with all hot/neutral runs. It has only the function of "protective earth" (P.E.).

Non-earthed setups are pretty much non-existent, although old houses with no P.E. wiring exist. The *requirement* for including a P.E. conductor came in about 1968, but was used before that.

For some very remote areas a single conductor with earth return may exist.... no pole neutral. otherwise same, with local neutral and earthing same as for above.

Anything else is probably so old as to be irrelevant, at least for residential. Industrial/commercial has other variations amounting to the same thing in the end.

motomoron
03-16-2011, 09:36 AM
I had a dryer do something much like this some years ago.

On the 220V/30A breaker , which is in essence a pair of 110V breakers ganged, one side had failed. The breaker didn't show as tripped, and cycling it off and back one didn't help.

A new breaker fixed the problem.

lost_cause
03-16-2011, 02:56 PM
99% of our dryers do indeed use the ground as a neutral. If you have a three wire dryer cord and receptacle, your dryer is using the ground for a neutral.

This is a good link as to the old and the new:

http://www.ask-the-electrician.com/wiring-a-dryer-power-cord.html

Mark

to elaborate a little, when you have a three wire cord, they may be using the ground wire as the neutral only for the 120v portion of the dryer, which would be the controls, etc. the 240v portion does not use a neutral wire. the return leg for the current is the opposing hot wire on a 240v draw.