[Amps] Re: Neutral and ground is in how you use them (was SB-220 on 220V)

[R.Measures]

>
>
>R.Measures wrote:
>> 
>
>> 
>> **  The neutral in the 240V outlet for the amplifier is shared with every 
>> 120V and every 240V circuit in the house because All of the neutrals 
>> connect to the neutral/ground terminal strip in the breaker-box.  If I am 
>> fortunate, it is that I know Ohm's law good enough to get by. 
>> 
>> __  Which is what I do on the 240v outlet for the tetrodes-with-handles 
>> mains outlet.  //  The imbalance current is c. 85mA-avg in the 
>> neutral/ground because I utilize one side of the mains-neutral potential  
>> to power a half-wave rectified, C-filtered 160VDC supply for operating 
>> the high-speed T/R relays.  Although there are some who would be alarmed 
>> about the potential-drop in 99' of #6 wire at 85mA, I am not one of them. 
>>  
>> 
>
>Rich, I am sure that you know and understand this stuff but some others 
>may not.
>
>1. The biggest reason for having separate ground and neutral wires is to 
>insure safety in case the neutral should open (in the case of a common 
>ground/neutral system like you use.
>Even your 85 ma that you are running on your common ground/neutral line 
>can be a hazard. If the ground/neutral line opens anywhere you will have 
>120 volts at chassis through the transformer primary with enough current 
>to cause electrocution if you are between chassis and some other ground.
>
** Providing this person was standing in water.

>In your system it may not be too likely to happen. However in many 
>wiring installations it can easily happen.
>
>One house that I owned years ago (was a brand new house too) had 
>problems with some of the wiring. Upon further looking I found that just 
>about every outlet in the house had the wires wrapped around the screw 
>terminals loosely as you normally would, but the screws were never 
>turned down! Most of the outlets worked properly as far as I knew. I 
>would have never known if I had not opened them up and looked at them. 
>That is unless I had a fire first!
>Suppose in that house I had a 220 outlet with only 3 wires used as you 
>do above. I could have very easily had a poor (guaranteed to be poor!) 
>neutral/ground lead.
>
>If your 220 line had it's ground/neutral connection wired like that and 
>you were using it as a neutral/ground you could very easily have a "hot 
>chassis". I have also seen "electrician" installations where the lugs in 
>  the breaker panel where not tightened. Wires slipped into hole but 
>never tightened down. they make a connection but not a reliable one.
>
>It is easy to have a poor outlet connection too. Fingers in the plug not 
>making proper contact. Especially on older / well used outlets.
>
>If any of these things happen on your neutral/ground line then you are 
>sure to have a "hot" chassis because you are asking that line to carry 
>current that is tied to the chassis.
>
>But if you have a separate neutral and ground line then even if you 
>would have a poor connection on ANY of the lines (even the ground line) 
>you would not have a "hot" chassis. Unless of course there were multiple 
>faults.

**  If the screws are not tightened on the ground and neutral wires, you 
would.  
>
>2. As to "proper to code installation of wires" you may use any color 
>wire that you wish. Even all black wires. Yes even for ground and 
>neutral! But each end is supposed to be tagged with proper colored tape 
>to identify them.

**  I identify them by size.  #6 is ground/neutral and the #4s are mains. 
 

>I do it in my own stuff mainly to be able to identify what I did several 
>years latter.
>If you use 3 conductor Romex for a 220 line (black, white and bare)
>the white wire should be marked with red tape on each end. The main 
>reason to do so is to tell someone that may be in that circuit doing 
>repair work that that is a 220 line and not a 120 volt line neutral.
>
>3.  A three wire 220 line as above is perfectly fine with the NEC as 
>long as it is used as "hot, hot' ground and no neutral is involved.

**  How can neutral be not involved if the not-hot third wire connects to 
the ground/neutral terminal strip?
>
>A 3 wire 220 line is fine for most of the amplifiers provided there is 
>no 120 volt / neutral requirement.

**  I have been using one half of the amplifier's 240vct, 20A circuit to 
power my 120v radio and soldering iron for the past 28-years.  
>
>4.  I saw someone post earlier that "ground wires and neutral wires were 
>intermingled on the lugs in the breaker panel". Even though the two buss 
>bars are tied together in the panel the proper way (to NEC code) is to 
>connect all the neutral wires to the neutral buss bar and all the ground 
>wires to the ground buss bar and not intermingle them.

**  In my General Electric Co. box there is one common strip for all of 
the neutral and ground wires

>There is good reason for it. 

**  Apparently, GE did not think so.

>Though they may be electrically the same, 
>it is much easier to identify which is which when looking in the crowded 
>panel to try and identify a wire. Also if you have an external main 
>breaker or this panel happens to be a sub panel the ground and neutral 
>would NOT be the same at that point.
>
>5.  Yes inspectors do (should) look for properly identified (proper 
>color) wires. You may know what they are on your own work but the next 
>guy that comes along may not know where they are supposed to go unless 
>they are the standard color codes.
>
**  I trust my DMM more than I trust a color.

cheers, Gary