Why I need 10/3 for dryer?

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mbrooke said:
I disagree, dryers have always needed a neutral. In fact the NEMA 10-30r receptacle has always been classified as none grounding 3 pole 3 wire.

Also, its not just the controls:
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I'm also with you on this. I think it was even more common years ago then it has been more recently to see same motor and same 120 volt control timer used on 120 volt gas dryer as was used on the 120/240 volt electric dryer made by same manufacturer.
 
kwired said:
I'm also with you on this. I think it was even more common years ago then it has been more recently to see same motor and same 120 volt control timer used on 120 volt gas dryer as was used on the 120/240 volt electric dryer made by same manufacturer.
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Thats what it boils down to. Most of the parts are interchangeable.
 
Don't know I had that one that the nameplate was 240v. only two terminals only green wires. or green with yellow. I did not look at the schematic though.

I used a 240v and ground cord and cap. not a dryer type.
 
Sierrasparky said:
Don't know I had that one that the nameplate was 240v. only two terminals only green wires. or green with yellow. I did not look at the schematic though.

I used a 240v and ground cord and cap. not a dryer type.
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How much do you want to bet that when that dryer eventually fails and gets replaced by a 120/240 dryer the person who installs it will just wire your cord to the new dryer as if it were two hots and a neutral? And it would not qualify for the exception, of course, even if that person moves the panel end from ground bar to neutral bar.
:)
 
GoldDigger said:
How much do you want to bet that when that dryer eventually fails and gets replaced by a 120/240 dryer the person who installs it will just wire your cord to the new dryer as if it were two hots and a neutral? And it would not qualify for the exception, of course, even if that person moves the panel end from ground bar to neutral bar.
:)
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Good point.
 
Sierrasparky said:
Don't know I had that one that the nameplate was 240v. only two terminals only green wires. or green with yellow. I did not look at the schematic though.

I used a 240v and ground cord and cap. not a dryer type.
Click to expand...
I once had to install range receptacles in an apartment complex that originally had gas ranges, as well as install cords and set the ranges in place as I changed them. These were only 24 inch wide ranges (apartments were small and range space was limited otherwise typical 30 inch range likely costs less just because they produce more of them).

Those ranges had no 120 volt loads in them, but still had the typical three pole terminal block with a bonding strap from the center terminal to the frame. I still installed 4 wire receptacles and cords, as someday they could be changed to something that does have a neutral and because a multiwire circuit is just standard for ranges. I would have done same for a dryer for same reasons.
 
mbrooke said:
I disagree, dryers have always needed a neutral. In fact the NEMA 10-30r receptacle has always been classified as none grounding 3 pole 3 wire.

Also, its not just the controls:
Click to expand...

When you say that dryers have "always" needed a neutral just how far are you going back? "Always" can be quite a long time.

The appliance repairman that told me that older dryers didn't need a neutral did so in 1981 and he had been in the appliance business since the late 40s or early 50s.

The automatic clothes dryer for residential use went on the market just before world war two and I have never seen a wiring diagram for one of the older one's.

There is no real good reason for a dryer to need a neutral even today. The British will sell you one that doesn't.

There are millions of older homes out there that have not been rewired and in most cases it would have been cheaper all around to have a 240V dryer and use the third uninsulated conductor as ground.

The idea of bonding the frame of a dryer to neutral was a very bad idea (think open neutral).
 
growler said:
When you say that dryers have "always" needed a neutral just how far are you going back? "Always" can be quite a long time.

The appliance repairman that told me that older dryers didn't need a neutral did so in 1981 and he had been in the appliance business since the late 40s or early 50s.

The automatic clothes dryer for residential use went on the market just before world war two and I have never seen a wiring diagram for one of the older one's.

There is no real good reason for a dryer to need a neutral even today. The British will sell you one that doesn't.

There are millions of older homes out there that have not been rewired and in most cases it would have been cheaper all around to have a 240V dryer and use the third uninsulated conductor as ground.

The idea of bonding the frame of a dryer to neutral was a very bad idea (think open neutral).
Click to expand...

I have worked on homes with very old dryer receptacles and wiring. They have all been NEMA 10-30's. I don't think I have ever run across a NEMA 6-30 dryer receptacle.

As stated in earlier posts the manufactures want to use the same motors and controls in electric dryers that they use in gas dryers.

The European's use single voltage appliances so it makes sense that they would not need a neutral for American use.
 
Sierrasparky said:
Don't know I had that one that the nameplate was 240v. only two terminals only green wires. or green with yellow. I did not look at the schematic though.

I used a 240v and ground cord and cap. not a dryer type.
Click to expand...

GoldDigger said:
How much do you want to bet that when that dryer eventually fails and gets replaced by a 120/240 dryer the person who installs it will just wire your cord to the new dryer as if it were two hots and a neutral? And it would not qualify for the exception, of course, even if that person moves the panel end from ground bar to neutral bar.
:)
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What are you going to do? I hooked up some soft ice cream machines from China. I kept trying to talk to someone at the shop where the machines were being custome made but could only talk to sales people. I wanted to make sure they would operate on 208V.

They slapped a name plate on the equipment that said 208V 60 hz and a UL sticker. I installed them and everything seem to work OK but I wouldn't bet on the life of the machines.
 
Latest Code

Latest Code

I have a Wiring simplified book that goes by the latest code, which was 1962 when the book was printed. :)

I like to see their explanations that lead to some of the older wiring I have seen or worked on.

For clothes dryers it reads:
Dryers are 230 volt devices although some have 115 volt motors in them. The Code requires that the frame of the dryer be grounded. But permits it to be grounded by means of the neutral conductor in the wiring, { provided it is #10 or larger} so 3 wire cable must be used even if the entire dryer operates at 230 volts. The code considers dryers to be portable devices.

Well, even back then the 1962 code said it needs to be a 3 wire cable. The change in 2014 NEC, seems to be from the neutral to the equipment ground. As the neutral is being utilized with the device. With an Exception: For existing branch circuit-installations only where an equipment grounding conductor is not present in the outlet or junction box the frames of clothers dryers shall be permitted to be connected to the grounded circuit conductor. But it has to be at least 10 AWG.
 
growler said:
When you say that dryers have "always" needed a neutral just how far are you going back? "Always" can be quite a long time.

The appliance repairman that told me that older dryers didn't need a neutral did so in 1981 and he had been in the appliance business since the late 40s or early 50s.
Click to expand...

As far as the early 50s and Im sure it was earlier. Even vintage models have 120 volt motors. The appliance tech may not have known the difference between ground and neutral for a dryer.


Here is an example of a 60s dryer, it even needs a 50amp supply (has an extra 2,800 watt heater):


http://www.automaticwasher.org/cgi-bin/TD/TD-VIEWTHREAD.cgi?14147





The automatic clothes dryer for residential use went on the market just before world war two and I have never seen a wiring diagram for one of the older one's.
Click to expand...

See pic of a high end 60s version. I will find more, they are all over vintage restoration sites.


There is no real good reason for a dryer to need a neutral even today. The British will sell you one that doesn't.
Click to expand...

:lol: Thats so true.

There are millions of older homes out there that have not been rewired and in most cases it would have been cheaper all around to have a 240V dryer and use the third uninsulated conductor as ground.

The idea of bonding the frame of a dryer to neutral was a very bad idea (think open neutral).
Click to expand...


I agree, not to mention so many DIYs (and even sparks back then) screw it up. Around here tons of condos have 10-2 going to the dryer with the bare EGC landed on the ground bar. Even my uncle who was an electrician taught me dryers only need "2 hots and a ground"
 
curt swartz said:
I have worked on homes with very old dryer receptacles and wiring. They have all been NEMA 10-30's. I don't think I have ever run across a NEMA 6-30 dryer receptacle.
Click to expand...

degupita said:
I have a Wiring simplified book that goes by the latest code, which was 1962 when the book was printed. :)

I like to see their explanations that lead to some of the older wiring I have seen or worked on.

For clothes dryers it reads:
Dryers are 230 volt devices although some have 115 volt motors in them. The Code requires that the frame of the dryer be grounded. But permits it to be grounded by means of the neutral conductor in the wiring, { provided it is #10 or larger} so 3 wire cable must be used even if the entire dryer operates at 230 volts. The code considers dryers to be portable devices.

Well, even back then the 1962 code said it needs to be a 3 wire cable. The change in 2014 NEC, seems to be from the neutral to the equipment ground. As the neutral is being utilized with the device. With an Exception: For existing branch circuit-installations only where an equipment grounding conductor is not present in the outlet or junction box the frames of clothers dryers shall be permitted to be connected to the grounded circuit conductor. But it has to be at least 10 AWG.
Click to expand...

mbrooke said:
As far as the early 50s and Im sure it was earlier. Even vintage models have 120 volt motors. The appliance tech may not have known the difference between ground and neutral for a dryer.

I agree, not to mention so many DIYs (and even sparks back then) screw it up. Around here tons of condos have 10-2 going to the dryer with the bare EGC landed on the ground bar. Even my uncle who was an electrician taught me dryers only need "2 hots and a ground"
Click to expand...

From what I can find the code allowed 2 hots and a neutral for a dryer circuit from 1947 until 1996. NEMA 10-30 Receptacle.

In the early 60s grounding of appliance frames was required as degupita states in his post. They allowed the use of the grounded conductor (neutral).

But they have made and still sell a NEMA 6-30 dryer receptacle with two hots and a ground. The manufacturers call it a dryer receptacle, that's not a name I gave it. I have never used one for a dryer but have used them a couple of times for other installations.

The book that Degupita refers to states that some dryers have a 120V motor.

When I say this guy said that older dryers didn't need a neutral he could have said that some of the older dryers didn't need a neutral. It's been a long time and I may have old timmers disease.

I remember haveing a discussion with him ( I worked for him part time) about how it didn't seem right to bond ground to neutral in a machine. My electrical experience at that time had mostly been military and not concerned with codes.

The manufacturers could just have easily used a 240V motor for the gas dryer because with only the motor load it would not have needed to be larger than #12 or even #14 and the only difference would have been the breaker and receptacle. Today you wouldn't need arc fault or GFCI.
 
growler said:
The manufacturers could just have easily used a 240V motor for the gas dryer because with only the motor load it would not have needed to be larger than #12 or even #14 and the only difference would have been the breaker and receptacle. Today you wouldn't need arc fault or GFCI.
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True, but consider not all homes had 240 back then. In fact some manufactures let you re-wire their 120/240 electric dryers to 120 volt having 1/4 the heating power. It was even listed on the nameplate.

In reality straight 240 volts would have been best, but back then things were different which set the trend we see today.
 
growler said:
There is no real good reason for a dryer to need a neutral even today. The British will sell you one that doesn't.
Click to expand...

iwire said:
It is just a matter of unit cost. They save every cent they can on each unit.
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I fully agree that it's a matter of cost for the manufacturer. If they can save a few cents that's enough for them.

If they used 240V motors and controls ( different step down tranformer ) then 10-2 with a ground would be perfect. The unit may cost more but what does it cost to up-grade the wiring. I guess I should say what did it cost to up-grade the circuits because you don't see many old range or dryer circuits.

Or the NEC could have required an insulated neutral and ground back in the early 60s.
 
mbrooke said:
True, but consider not all homes had 240 back then. In fact some manufactures let you re-wire their 120/240 electric dryers to 120 volt having 1/4 the heating power. It was even listed on the nameplate.

In reality straight 240 volts would have been best, but back then things were different which set the trend we see today.
Click to expand...


I hadn't thought of that. I grew up living in the country and most all of the services were 240V because of the electric ranges ( no gas available ). People tended to get electric ranges years before electric dryers so as to stop chopping wood and overheating the house in summer. . Those automatic dryers were expensive and not a necessity, clothes lines were cheap and the sun worked for free.
 
growler said:
I hadn't thought of that. I grew up living in the country and most all of the services were 240V because of the electric ranges ( no gas available ). People tended to get electric ranges years before electric dryers so as to stop chopping wood and overheating the house in summer. . Those automatic dryers were expensive and not a necessity, clothes lines were cheap and the sun worked for free.
Click to expand...

Conversely, I came up with 240 always being available, but we had ng and used it for everything-Heating (dearborns in every room, a peerless wall heater in bathroom), cooking, and we had a gas dryer and w.h. too.:)

Actually come to think of it, I don't think we ever used anything at all that required 240- even the 2 ac window units we had were 120.
 
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