Any standard that a Distribution Utility should comply in this grounded service conductor or neutral? Should it have a minimum size or specification?
Should the end user allow the Distribution Utility to charge him with the line losses of the grounded service conductor or neutral conductor?
Line losses happen in all conductors unless you can find one that has absolutely no resistance.
There are also losses in transformers and other distribution components - ultimately the consumers are paying for those losses, but not through direct metering of those losses. Why do you think the customer meter records line losses ahead of the meter? True the neutral conductor most cases isn't even metered, but what comes in on the ungrounded conductors is, and if it doesn't come back on the other ungrounded conductor(s) it doesn't get added to the count.
There are single phase 120/240 metering systems that use a single CT to capture current for the metering. Both ungrounded conductors pass through this CT but in opposite directions in relation to the supply side. There may be a little more to this but to keep things simple it is basically metering at 120 volts, should there be a 240 volt load the current in the CT is doubled because both circuit conductors are passing through the CT - it doesn't matter that the neutral isn't monitored, because all the current of a 120 volt circuit is equal in all portions of the circuit, so if the ungrounded conductor passes through the meter you have already captured the current of that load for metering, and it could care less if the return path is the neutral conductor, the water pipe that was used as a grounding electrode, the shield on the phone cable or any other path.
Most states have regulations on delivered power as well, and the POCO's need to be within at least 10% of the nominal voltage, probably at the metering point, or possibly wherever customer owned equipment starts anyway. Also keep in mind the neutral is generally only carrying imbalanced current of the other conductors, so better balancing will ensure less neutral losses. For a typical residential service I'd guess the losses in the neutral would be low enough it doesn't matter much, for a higher demand commercial or industrial facility, they are probably looking closer at their own losses beyond the service point and trying to maintain balance anyway.
I won't say there is no losses in the unmonitored neutral conductor because obviously if there is a voltage drop across any conductor there is a resistive loss. But what is voltage drop going to be over a reasonably balanced neutral to a typical residential or light commercial service? Remember if you are measuring line to neutral voltage at the service any drop you see there is a composition of drop in both grounded and ungrounded conductors, you need to measure the drop across the neutral itself to see what is lost in the neutral. If you only have a 1.5 volt drop and a current of 10 amps that is a 15 watt loss. If your energy rate is 10 cents/kWhr that is .15 cents per hour lost - assuming that you maintain that load creating this loss for an hour. If you kept that load constant for 24 hours you lost 3.6 cents in one day. Dwelling and light commercial loads are usually not that constant so chances are you have high and low periods throughout any given day - but the net is possibly lower then this example. One could possibly offset that cost easily just by remembering to turn off a light in a space that doesn't get much use.
Larger services usually have large conductors and they are usually underground - so no steel strand in those cases, yet they often have neutral issues involving harmonics and can still have losses on the unmetered neutral conductor.
POCO medium and high voltage distribution/transmission overhead lines also use conductors with a steel strand for added support - if they didn't those lines would come down much more often then they do, or we would need much closer spacing between support poles/towers. Either way those things probably end up costing much more then what little loss there may be because of reduced conductivity that results in that steel strand.
I went to an open house Q&A session a couple years ago, related to a current transmission line project that is now starting in the area. This was for a 345kV line being built in the area. Though it was the "shield" wire that they had a sample of - they can embed fiber optic strands into those overhead lines as well for communications between substations, switch yards, etc.
It all comes down to knowing what you have for a conductor and setting a design standard when it comes to determining what size of conductor is needed. POCO's do often have their own standards, but also need to comply with utility regulating commissions, when it comes to quality of what gets delivered to the consumer, and they usually can meet those standards with less restriction in materials selection then if they would have to follow the NEC for selecting conductor sizes. I can't tell you how many times I have seen residential service drop of only #2 or #4 AWG aluminum (with steel strand in the neutral) supplying a 200 amp service - but seldom see any troubles with that service either - because the service is not really loaded that much or for very long if it does have a fairly significant load at times. If you want them to change things like this - it will cost the consumer more money then what losses are on current designs in most instances.
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