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Balanced load, splitting a 220V outlet

HANKMARS

Jul 28, 2019
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In the main breaker panel I have a 50A, dual phase breaker. This feeds a typical electric clothes dryer outlet. Two hots, one neutral, one ground. I would like to go from that outlet to a 110V 4-way box. The 4-way consists of two duplex 110V three prong outlets. I would like to take phase A to one duplex and phase B to the other duplex using a common neutral and common ground. Will I run into a problem with this design?
 

Minder

Apr 24, 2015
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A common neutral shared between L1 & L2 results in the difference in current between L1 & L2. in the neutral.
For e.g. if L1 socket has a 10amp load and L2 also has a 10amp load, the current in the shareed neutral will be zero!
P.S. N.A. is 120v-240v
 

HANKMARS

Jul 28, 2019
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Let me see if I'm getting a grip on this. For instance; take an electric clothes dryer. I'm guessing the barrel drive motor, and heating element, and its blower fan, are in parallel with, and designed to utilize what is, I believe, called single phase 240V. Let's delete the blower fan. In theory, if the drive motor and the heater were drawing 7A each and shared a neutral, then the circuit would be operating at its highest efficiency as a 240V circuit. If the heater current were reduced to 4A, then 3 amps would be shunted off to neutral and efficiency would decrease proportionately, which is a guess on my part. Any truth to any of that?
 

Ylli

Jun 19, 2018
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Would work just fine - any imbalance in load would put current into the neutral, but as long as it is sized properly that should not be a problem. Is it to code?? Would need to ask an electrician or electrical inspector.
 

Minder

Apr 24, 2015
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In theory, if the drive motor and the heater were drawing 7A each and shared a neutral, then the circuit would be operating at its highest efficiency as a 240V circuit. If the heater current were reduced to 4A, then 3 amps would be shunted off to neutral and efficiency would decrease proportionately, which is a guess on my part. Any truth to any of that?
Yes, That is about the crux of it, the neutral would only pass any difference in current. i.e. not the sum.
If L1- N -L2 , there will be no difference in efficiency.
 

Tha fios agaibh

Aug 11, 2014
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Is it to code??.
Heck No!
This is a horrible idea and could be quite dangerous.

For one, you are powering receptacle outlets not rated for 50a but only 20a at most.
For another, if there was an overload or ground fault the wires would melt apart before tripping the breaker unless at least 6awg wire was used the entire length. Your not going to find a plug or duplex outlet that will accept 6awg wire.

If you short the wires of a typical lamp it will trip a 15 or 20a breaker even though zipcord wire is only size 18awg. Now do the same thing on 50a circuit and you might burn your house down when the lamp cord gets nuked.

Do yourself a favor and do a proper install of the outlet where you want it.
 

HANKMARS

Jul 28, 2019
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Would work just fine - any imbalance in load would put current into the neutral, but as long as it is sized properly that should not be a problem. Is it to code?? Would need to ask an electrician or electrical inspector.
Built with American tools by a two time Union member. " Code ?" that's subjective. I generally strive for above code and that pretty much lands me inside tolerable. My work generally exceeds the state of the foundation circuit, mainly because of tech advancement.
 

HANKMARS

Jul 28, 2019
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Heck No!
This is a horrible idea and could be quite dangerous.

For one, you are powering receptacle outlets not rated for 50a but only 20a at most.
For another, if there was an overload or ground fault the wires would melt apart before tripping the breaker unless at least 6awg wire was used the entire length. Your not going to find a plug or duplex outlet that will accept 6awg wire.

If you short the wires of a typical lamp it will trip a 15 or 20a breaker even though zipcord wire is only size 18awg. Now do the same thing on 50a circuit and you might burn your house down when the lamp cord gets nuked.

Do yourself a favor and do a proper install of the outlet where you want it.
Each circuit immediately enters another breaker panel with its distribution. Forgot to mention that.
 

HANKMARS

Jul 28, 2019
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Yes, That is about the crux of it, the neutral would only pass any difference in current. i.e. not the sum.
If L1- N -L2 , there will be no difference in efficiency.
My assumption is that neutral is the center tap of the line transformer, and from there, is taken to ground. Close?
 

Minder

Apr 24, 2015
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Yes the neutral is the centre tap of a 1ph 240v transformer secondary. It is taken to earth ground at the panel Only, but there is some exceptions which concern industrial control equipment where a grounded neutral is missing.
.If the two 120v circuits are protected at the rated current, you should be OK.
 

HANKMARS

Jul 28, 2019
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OK. Very good. I may have been seeing a ground wire on power poles and assumed that it was the neutral when in fact the ground wire is perhaps a safety measure should something up top go a muck. I suppose it would keep any static charges from accumulating also.
 

Minder

Apr 24, 2015
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OK. Very good. I may have been seeing a ground wire on power poles and assumed that it was the neutral when in fact the ground wire is perhaps a safety measure should something up top go a muck. I suppose it would keep any static charges from accumulating also.
Yes, the transformer N is earth grounded at the source as well as the Neutral entry point at the panel.
 
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