Why four wire instaed of three for range and dryer?

[iwire]

Anyway, it was my understanding that older model ranges and dryers operating on 240 volts did not need a neutral as they had no digital displays or internal electronics requiring the need for one.

As far as I know the drum motors have been 120 as long as they have been making electric dryers.

Here is a diagram, http://i160.photobucket.com/albums/t200/Zenzoidman/Dryers/dryer.jpg

 

[goldstar]

As far as I know the drum motors have been 120 as long as they have been making electric dryers.

Here is a diagram, http://i160.photobucket.com/albums/t200/Zenzoidman/Dryers/dryer.jpg

IF what you claim is 100% correct then I stand corrected.

 

[Dennis Alwon]

IF what you claim is 100% correct then I stand corrected.

I believe that to be true also. Not sure why the motor is 120v but they have been for a long time.

 

[stickboy1375]

It makes sense to make the dryer motor 120volts, think about installing a 240v motor with a 208v service, the heater will work just fine at that voltage, the motor won't play as nice?. It seems to be the manufactures best interest.

 

[iwire]

It makes sense to make the dryer motor 120volts, think about installing a 240v motor with a 208v service, the heater will work just fine at that voltage, the motor won't play as nice?. It seems to be the manufactures best interest.

:thumbsup:

I think you nailed the reason.

 

[kwired]

It makes sense to make the dryer motor 120volts, think about installing a 240v motor with a 208v service, the heater will work just fine at that voltage, the motor won't play as nice?. It seems to be the manufactures best interest.

True to a point, they are certainly capable of making a motor that will work on both 208 and 240, and there are many other motors out there that can.

I think there may also be some desire to use the same motor for a gas dryer that operates at 120 volt only.


I think people that are confused by this once allowed practice of using the grounded conductor for equipment grounding are confused for good reason. They ask why we were allowed to do so with a very limited application yet all other applications were not allowed to do the same? It really didn't really make that much sense, and in the 1993 or 1996 code I think the CMP finally came to a conclusion that it did not make any sense to have such exception - but still had to allow for existing installations.

The risk for an individual circuit here and there maybe wasn't all that high and is maybe why they decided it was acceptable, but if they would have allowed that practice for everything we would have stray current and voltage problems nearly everywhere.

 

[stickboy1375]

True to a point, they are certainly capable of making a motor that will work on both 208 and 240, and there are many other motors out there that can.

I think there may also be some desire to use the same motor for a gas dryer that operates at 120 volt only.

It all comes down to profit, why sell a dual voltage motor when a single voltage motor is cheaper to produce? Would you install 4 lamp ballasts for a 2 lamp fixture at your own expense?

I think people that are confused by this once allowed practice of using the grounded conductor for equipment grounding are confused for good reason. They ask why we were allowed to do so with a very limited application yet all other applications were not allowed to do the same? It really didn't really make that much sense, and in the 1993 or 1996 code I think the CMP finally came to a conclusion that it did not make any sense to have such exception - but still had to allow for existing installations.

The risk for an individual circuit here and there maybe wasn't all that high and is maybe why they decided it was acceptable, but if they would have allowed that practice for everything we would have stray current and voltage problems nearly everywhere.

I'm a firm believer the NEC is about consistency, so it only makes sense to remove this once allowed acceptation?.

 

[renosteinke]

Just what was the third wire? Neutral or ground?

Seems to me the wire was a ground. The issue was that 220V appliances often needed 120v; ranges had convenience receptacles mounted on them (quite common in the 60's), ovens had lights, and dryers had their drum motors. This meant normal operation put current on the ground wire.

Or, perhaps, the wire really was intended as a 'neutral.' Consider that even today many homes lack any ground wires. and the original service lacks a ground bar. My house, built in 1957, was such a house. (Romex was the method). I've seen even commercial / government facilities built in the mid-70's (by exceptionally competent contractors) that use the pipe between panels as both neutral and ground.

When one such facility had a failure over a Thanksgiving holiday, it was a failure of the bonding between panels that proved to be the culprit. These days, we have all manner of electronics in our circuits. The effect is that 'power quality' -something unheard of in the 60's- is really important. Even our ranges and dryers have electronics in them. So, we really need to keep the neutral and the ground separate.

 

[meternerd]

1. How likely would that be?
2. In the event that it did happen, wouldn't the ground be a more conductive path anyway? Granted, we don't know the length of the run, but in general, wouldn't the existing path be more conductive than my elbow?

Not arguing your point, just really curious about this now that it was asked of me.

btw, Happy Holiday's to those celebrating!

We had a fatality here a few years ago. Sent us (the POCO) to investigate the possibility of service problems. 12 yr old girl came in from playing outside, grabbed the stove while hanging onto the water faucet. Turns out there were bonding problems with the GEC and water piping bonds, but the killer was that the neutral on the stove had never been connected and there was no EGC. Measured solid 120V from stove frame to ground with one burner on. Damaged wiring going to one of the burners caused a short to the range frame. The house was pretty old, so it's amazing that no one was injured earlier. Just one example. I'm sure there are many more.

 

[stickboy1375]

Just what was the third wire? Neutral or ground?

Seems to me the wire was a ground. The issue was that 220V appliances often needed 120v; ranges had convenience receptacles mounted on them (quite common in the 60's), ovens had lights, and dryers had their drum motors. This meant normal operation put current on the ground wire.

Or, perhaps, the wire really was intended as a 'neutral.' Consider that even today many homes lack any ground wires. and the original service lacks a ground bar. My house, built in 1957, was such a house. (Romex was the method). I've seen even commercial / government facilities built in the mid-70's (by exceptionally competent contractors) that use the pipe between panels as both neutral and ground.

When one such facility had a failure over a Thanksgiving holiday, it was a failure of the bonding between panels that proved to be the culprit. These days, we have all manner of electronics in our circuits. The effect is that 'power quality' -something unheard of in the 60's- is really important. Even our ranges and dryers have electronics in them. So, we really need to keep the neutral and the ground separate.

It IS a neutral, NOT A GROUND?. today it is still a grounded conductor. This is the biggest problem, people just assume because it is bare than it must be a grounding conductor, but the NEC is very clear on this.

 

[stickboy1375]

These days, we have all manner of electronics in our circuits. The effect is that 'power quality' -something unheard of in the 60's- is really important. Even our ranges and dryers have electronics in them. So, we really need to keep the neutral and the ground separate.

So what do you want to do about the service? :angel:

 

[qcroanoke]

As far as I know the drum motors have been 120 as long as they have been making electric dryers.

That is something I did not know until about 10 years ago.

 

[Little Bill]

IF what you claim is 100% correct then I stand corrected.

There has been a lot of IF scenarios posted here and of course we all know that IF is one of the biggest words in the English language. Anyway, it was my understanding that older model ranges and dryers operating on 240 volts did not need a neutral as they had no digital displays or internal electronics requiring the need for one. Newer models require a neutral to run the internal electronics and displays which leads me to my age old gripe that I've posted here many times "why can't manufacturers make the units with a transformer and re-manufacture the voltage they need for the internal electronics"? That way you only need the ground.

Now, let me post some of my own IF's

• IF you check the units when they're shipped to the residence, the neutral and ground are bonded together at the connection terminal.
• IF you don't separate them at the unit you haven't accomplished anything by running a 3-wire cable

How many homeowners know enough to do this ?

Since you're in the mood for correction, I think you meant 4-wire cable in your second IF.

Not only do most homeowners not know to remove the bonding strap, neither do most of the appliance installers!:happyno:

 

[ActionDave]

IF what you claim is 100% correct then I stand corrected.

I have seen a European brand dryers, Asko (sp?) that were 240V only; two hots and an egc were all that was needed. Funny thing is since they were made for the US market they had a stud to land a neutral from the pig tail inside the unit but it was just a dummy.

As far as I know the drum motors have been 120 as long as they have been making electric dryers.

I will be so bold as to say for US domestic style all dryer motors are 120V.

 

[goldstar]

Since you're in the mood for correction, I think you meant 4-wire cable in your second IF.

Not only do most homeowners not know to remove the bonding strap, neither do most of the appliance installers!:happyno:

YOU are 100% correct in both cases.:happyyes:

 

[norcal]

The timer motor in dryers is 120V, then you have oven lights, & some older ranges had fluorescent or the really old ones used incandescent lamps, for lighting the cooking surface, convenience receptacles also, but I suspect GFCI requirements put those receptacles to pasture, also more receptacles in modern homes made them a unnecessary expense to appliance manufacturers.

I should start looking at the oven timers when the opportunity arises suspect that they are 120 volts also.

 

[iwire]

I agree with stickboy, it is all about costs.

Yes they could run them on straight 240 or 208 and I bet they would if it saved as much as $0.01.

Last spring I bought a new 'budget' washing machine and it is amazing how light it is, how small the motor is, how little there is too it.

The motor is about the size of a softball, its either DC or AC with an inverter as it is speed controlled.

 

[augie47]

Not only do most homeowners not know to remove the bonding strap, neither do most of the appliance installers!:happyno:

Amen to that !

 

[templdl]

Amen to that !

Ditto. Even when reinstalling a range or a dryer where there is a 4-wire receptacle and the appliance has a 3w plug when replacing the 3-w with a 4-w cord how often is the "insignificant" sometimes hard to see bonding strap removed?
In my own home which I'm the second owner it had a 4-w receptacle for the dryer and a 3-w for the range which were wired at the same time the house was built. Go figure.

 

[GoldDigger]

4-wire for the dryer makes perfect sense if it was installed before the 1953 Code was adopted locally.
It might also have been because it used smaller wire?

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