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#36160 - 03/30/04 12:02 AM A Case for No Neutral - Design Question  
Hutch  Offline
Member
Joined: May 2002
Posts: 381
South Oxfordshire, UK
I have a design question here guys – one that I’ve discussed briefly on the Chat line some time ago and Bill suggested that I put it on the general section. It concerns common household high voltage equipment mainly ranges and driers.

(A) Why do we persist in building 120/240V equipment?

(B) Why not design them to be 240V only?

Option (A) requires more copper wire, more metal in plugs and receptacles and, in older configurations, a safety compromise by combining the grounded and grounding circuits.

Heating elements in both ranges and driers tend to be 240V. Control systems/timers, fan motors and lights tend to be 120V. None of the latter need to be rated so.

With 240V available, it is far more efficient in terms of voltage drop to run the tumble-drier fan motor at the higher voltage and these motors are readily available. The control circuits would probably require only the substitution of a few, sub-penny components to make them happy with a 240V primary – the non-American ones (possibly greater in number, globally) already do so without a qualm.

The only problem I see is the light with the Edison Screw and the necessity for the shell to be a 0V to ground for safety. Therefore with this new configuration, do away with the Edison Screw and adopt a 240V Bayonet Cap lamp and double pole switching on the lighting circuit. This would hardly be expensive as eastern Europe produces large quantities of 240V BC oven lights for their own domestic market.

A 240V system would also be downward compatible to use the computer jargon. In present installations, especially those three wire ones, no neutral circuit would be required – the 0V line would be dedicated to grounding. In time, we could wean ourselves off this currently, compromise arrangement.

With best regards, what say you?



[This message has been edited by Hutch (edited 03-29-2004).]


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#36161 - 03/30/04 12:39 AM Re: A Case for No Neutral - Design Question  
Jps1006  Offline
Member
Joined: Jan 2004
Posts: 615
Northern IL
Hutch,

I think you got a winner there. I especially like the idea of less wire, smaller pipe, etc.

I can only imagine that the only reason we still do 120/240 is out of habit.

Didn't NEC 2002 pull out the exception that allowed the neutral and the ground to be bonded on ranges and dryers? It my have been earlier.


#36162 - 03/30/04 05:07 AM Re: A Case for No Neutral - Design Question  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
I'll second the reasoning that it's probably out of habit mainly.

You'd need to educate users to look for 240V bulbs as replacements, but at least the "funny looking" BC bases would stop them just screwing in regular 120V ES bulb and the resulting consequences. People these days are probably more used to looking for unusual style bulbs anyway with the varieties commonly used in microwave ovens.

By the way, Whirlpool now manufacture washers and dryers for the British/European market. I was in Comet (big electrical retail chain) a few days ago and saw the large Whirlpool machines (take about a 22 lb. load) on display, complete with "Made in U.S.A." tag on the panel, so at least some production in the U.S. is already for 240V. If they can turn out export machines for 220-240V 50Hz, then it probably wouldn't take too much to do a 240V 60Hz range to UL/CSA specs.

(Nice to see American-made appliances on sale here, by the way. They're few and far between on the whole. [Linked Image])


#36163 - 03/30/04 12:06 PM Re: A Case for No Neutral - Design Question  
Active 1  Offline
Member
Joined: Feb 2003
Posts: 687
Grayslake IL, USA
Change is too difficult for the user. Why do most of are cars still use gasoline? Why don't we use the metric system?

Your right it might be better. How many consumers would want to buy the first 220v only house? Every time they they want to buy something electric for the home what do they do? What is the value of the home to the next person? Whould anyone spend money to rewire their home to a more efficient system? I have a hard enough time selling things that are needed for safty.

On the other end of the spectrim I came across at least one web site where people think homes should be wired in 12V. They just don't understand voltage drop.

Tom


#36164 - 03/30/04 03:10 PM Re: A Case for No Neutral - Design Question  
Hutch  Offline
Member
Joined: May 2002
Posts: 381
South Oxfordshire, UK
A1, My question only relates to ranges and driers currently supplied at 120/240V and not to general circuits at 120V. A 240V only range or drier could be powered without any change to existing HV circuits.


#36165 - 03/30/04 07:10 PM Re: A Case for No Neutral - Design Question  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
I can offer ‘olde basterd’ reasoning for 120/240V service to electric cook tops and clothes dryers. On cook tops, burner heat levels were varied by a switch connecting two different-wattage heater elements per burner to a combination of 120 or 240V.

Clothes dryers used to have labels on their backs showing operation on 120/240V OR 120V only. At 120V, the 240V 4500W heater would work at only ~1100W, but it was intended to as needed.


#36166 - 04/01/04 08:11 PM Re: A Case for No Neutral - Design Question  
classicsat  Offline
Member
Joined: Nov 2002
Posts: 456
What's next, 2.5KW kettles? How about direct import Espresso machines?


#36167 - 04/01/04 10:35 PM Re: A Case for No Neutral - Design Question  
Hutch  Offline
Member
Joined: May 2002
Posts: 381
South Oxfordshire, UK
Quote
What's next, 2.5KW kettles?

3kW is more my style. Anything less doesn't do justice to the water!

Anyone for tea?


#36168 - 04/02/04 04:24 AM Re: A Case for No Neutral - Design Question  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
A lot of the newer jug-style kettles here are only 2kW or thereabouts. Many of the older traditional-style stainless steel models were a full 3kW.



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