I would assume that we are not allowed any assumptions about neutral or bond in this thread.

I don't see the words, "neutral" or, "bond" on that drawing. I don't see neutral arriving with the power wires. Is neutral represented as the earth symbol and bond represented by the earth symbol with X2 next to it?

 

I don't see the words, "neutral" or, "bond" on that drawing. I don't see neutral arriving with the power wires. Is neutral represented as the earth symbol and bond represented by the earth symbol with X2 next to it?

It is normal for 3ph phase and earth ground only to be delivered to an enclosure, (although I agree it is not shown) usually derived from the earthed star point of the transformer.
In these cases the local neutral is set up as previously described, by grounding one side of the secondary of the control transformer, this is done right at the secondary terminal and this point is bonded to the service ground and the neutral is then taken from this point, indicated in white conductor.
Max.

 

OK, but neutral in this case does not mean the same as it does with split phase 240VAC American. This neutral is not a current return to the 3 phase source. This alleged neutral is only a local neutral of a transformer isolated subsystem. I think you've confused the issue and further discussion of 3 phase neutrals that do not function in any way related to the circuit of the OP should be terminated.

 

OK, but neutral in this case does not mean the same as it does with split phase 240VAC American. This neutral is not a current return to the 3 phase source. This alleged neutral is only a local neutral of a transformer isolated subsystem. I think you've confused the issue and further discussion of 3 phase neutrals that do not function in any way related to the circuit of the OP should be terminated.

The neutral in a split phase system does not 'return' to the original 3 phase supply it is just referenced, or re-referenced to it, a 120v single phase transformer in an enclosure is no different from a single phase centre tapped transformer sitting on a pole outside that has the centre tap referenced to earth ground.
It is the fact of earth grounding it that declares it 'neutral'.
The local control transformer neutral is not 'alleged' it is actual.
Max.

 

I disagree. The fact of earth grounding a local transformer secondary with a non-current carrying conductor makes it a bond wire. One of the local transformer wires might be declared as neutral for that subsection of the machine because it carries current, but why introduce another definition of neutral to a beginner instead of using "common A" for the A subsection and, "common B" for another secondary winding? How many current carrying neutrals and non-current carrying neutrals do you want to be talking about here?

I think Max means 2 of the red lines in my drawing are not bond. Two of them are now, non-current carrying neutrals from the two isolated secondaries. Does that clear things up?

 

You can see that each transformer secondary is attached to the Bond point.That thing called "2LT" seems to be a light bulb (or some other kind of load). In my world, attaching it to Bond is not right. It should be attached to, "#16 AWG wht" (that vertical line on the right).

I did see that and asked myself the same question. I would have finished the connection across to branch 2.

Also, what do the two little vertical o o with directional arrows just right of each light (lines 212, 216, 217 & 219) indicate? I have never seen that notation used. One is pointed right to branch 2 and the three others are pointed left to branch 7?

 

what do the two little vertical o o with directional arrows just right of each light (lines 212, 216, 217 & 219) indicate?

I don't know.
Right now, I'm trying to magically burn that image out of your eyes because it introduces a 3 phase power supply you aren't using, with neutrals that never have any connection to the power source, and non-current carrying neutrals that are connected to current carrying neutrals, which are all connected to earth somehow, but the wiring is not depicted, just a lot of earth symbols with no explanation of how the wires are routed. Is that clearing anything up for you?

 

I don't know.
Right now, I'm trying to magically burn that image out of your eyes because it introduces a 3 phase power supply you aren't using, with neutrals that never have any connection to the power source, and non-current carrying neutrals that are connected to current carrying neutrals, which are all connected to earth somehow, but the wiring is not depicted, just a lot of earth symbols with no explanation of how the wires are routed. Is that clearing anything up for you?

Yes it does #12!! You and Max's discussions and comments have cleared up many things I have been struggling to grasp these past couple of months! Now I have to spec out the breakers and fuses!

Thankyou kindly!

 

Well I'll be! I thought I was failing badly by having a sidebar with Max, and frankly disagreeing with him. You find that educational? You're a better man than most.

 

I could go on about the definition of Neutral's but it might start adding unnecessary clouding over of the original question.
Max.

 

Also, what do the two little vertical o o with directional arrows just right of each light (lines 212, 216, 217 & 219) indicate? I have never seen that notation used. One is pointed right to branch 2 and the three others are pointed left to branch 7?

That was the first time I had noticed it, I have a later full copy of the NFPA79 (also have in PDF) which shows a slightly different Earth Ground symbol, I suspect it is a method of showing by lamp that the secondary has an earth grounded system in place and is valid? that is the only thing I can think off apart from a GFI ground missing type device.
Max.

 

I am a great fan of, "slightly different ground symbols". They can make all the difference in understanding a circuit.

 

A search found the newer example and I was in the process of researching it.

I was going to wait on posting til I knew, but then that never stopped me before.

This is informative, but doesn't help explain.

The 5018 is "clean ground".
"No. 5018 Noiseless (clean) earth (ground): To identify a noiseless (clean) earth (ground) terminal, e.g. of a specially designed earthing (grounding) system to avoid causing malfunction of the equipment."


The lamp must have special significance. Although I didn't find it in the complete text.

Could it be to show panel as being "live" in the event of open neutral?
A high impedance lamp could be allowed connection to ground in a special case, as an indication that panel is at ground/neutral potential?

So far I haven't seen the light.
Please post the answer if it's found.
I'm very interested, as this is the exact type of control circuit that I work with.

 

Could it be to show panel as being "live" in the event of open neutral?

I believe you mean a non-grounded neutral condition?
Or something like that, if the neutral were to open past the grounded point, the lamp would still light.
I notice when the lamp in question is pushed, it connects to neutral instead of earth ground in the normal non-pushed stage.
Max.

 

I believe you mean a non-grounded neutral condition?
Or something like that, if the neutral were to open past the grounded point, the lamp would still light.
Max.

Yes, that's what I mean.

No, in that I haven't thought it out through all the possibilities.

It does seem that the symbol is special. Redundant conductor just for safety? Why not a redundant neutral then? It would by definition be a neutral. (connected to neutral point and intended to carry current).

Oops, too quick for your edits.

What is "pushed"? That may open my eyes!
Is that the small arrows? Visible , by my poor eyes when expanded.

 

I notice when the lamp in question is pushed, it connects to neutral instead of earth ground in the normal non-pushed stage.
Max.

Push a lamp
I am completely lost on that one.

 

Now I'm getting lost in the different versions.
I have at least three up.

In this circuit from NFPA 79-2007
http://www.dxdlw.com/bbsupfile/2012%...0Machinery.pdf

Page down to 79-61 and blow up to 300%.

That one has the arrow symbols but no alternate path to #2.

Can't wait for "the rest of the story".

 

If you notice all those Indicator lamps have push to test, which connects the power side to 120v to test the lamp, in the case of the one with the query, I believe it is intended to be wired to an actual earth ground point pipe or rod, this will be a constant indication of a valid grounded neutral, the normal push to test switch connects it to the transformer secondary neutral for lamp test purposes. (neutral 108-1).
It is from NFPA79 -2002 same as 2007.
Max.

 

I also see that there is a Typo in the later NFPA, the original PDF I posted for NFPA is for 1997 where they use wire #7 for the 120v control live conductor, and they have carried this over on the lamp test terminals for the later prints, instead of changing to wire #115.
The small SPDT contact shown on the lamps is for lamp test function built into the P.B.
I normally use standard lamps and wire up a lamp test P.B. that lights all.
Max.

 

"Push to test" would explain the two dots with an arrow mentioned in post #46.