Choose 230/3/60 or 460/3/60 Power For Small Mill

None really, because the individual motor windings will be connected so that they run at the lower voltage, anyway. The larger of your motors will need one or two wire sizes larger, and maybe larger starters, but these probably won't add as much cost as a lighting transformer would.

Thanks for clearing that up. I was getting some confusing feedback from the contractor. So, all things bein equal, there shuouldn´t be issues regarding motor performance or shortend life cycle on account of thevoltage selected. right?

In Canada 575vac is quite common. The wire is lighter, and for longer runs it significantly reduces the copper usage for a given % voltage drop.

With your small motors you will probably run #10 anyways, so at half the current you will get half the voltage drop, noticeable in the longer runs. For across the line starting, the lower voltage drop starts the motor easier.

For a 100amp service at 460V you will have 2x the power available for essentially the same installed conductors and protection. This will be an asset when you want to add additional loads, electric heating, high intensity overhead lamps, and other loads you have not shown in your load summary.

I have always found the lighting transformer did not significantly change the cost.

My only caveat is the lighting transformer can be noisy if it is of poor quality.

The obvious reason for the higher voltage is lower amperage, but with so light a load, you are on no more than 30A breakers/ AWG 10 conductors for the largest loads anyway. Incoming service, if at 35KW (7 @ 5KW average) is still under the normal 100A service, no no savings here either. So, I agree with the elimination of the transformer idea - go with the lower voltage and run your lights on 120V with no stepdown.

Generally, running at the higher voltage would lower your installed cost. Less copper, smaller circuit components such as motor starters, breakers etc. Then if your motor loads are so small, you lighting needs are likely small as well, so the transformer issue is not that big of a deal.

But in this case I agree with the others, all of your motor loads are at the lower threshold of component and conductor sizes anyway, so there is little difference in the end. The only thing worth consideration is any possible expansion. If there is no chance if that, stick with the lower voltage.

But by the way, there is zero difference in the "safety" of 208V vs 480V, you will be just as dead if you make contact with either one. Common misconception.

Not to be anti-safety, but the line to ground voltage on the 230 is only 120VAC. I have personally been accidentally subjected to that (starting when I was only 2 years old and most occurred before I was 21) a few more times than I have fingers, but do not ever want to touch the line to ground voltage of the 460. (yeah, as a youth I was a bit careless in my experiments with electricity) Now line to line voltage is a different story - most likely dead either way. The way most are going to be accidentally shocked is from one line through a body part touching ground. (the most painful is from a finger through the heel of the hand - very short path - very low resistance) Give me the 230V please, if I am working on it.

...word to the wise. Thanks Phys.

Not to be anti-safety, but the line to ground voltage on the 230 is only 120VAC.

And the line to ground voltage on 480V Y systems is "only" 277. What's your point?

Fact: statistically, more people are killed each year in the US by electrocutions where the line to ground voltage is 120V than any other voltage (61% of all electrocution deaths are attributable to household appliances).

You were lucky. I was lucky on each of the 3 instances when I have been "bit" by 480V. But luck is not a safety strategy.

My point - I have a choice of maybe being bit by 120V or more than double that - which should I choose....??????????

Yes 120V is predominant in deaths as we don't give the commoners access to 277V for obvious reasons. If 277V was a common receptacle voltage, the death rate would undoubtedly soar.

Actually I have been bit once by 277V - don't trust disconnects - they can fail and not actually open the contacts. The disconnect opened 2 of 3 phases and I touched the one it didn't. Fortunately that time I was not well grounded anywhere - good to have rubber soles.

If you worked on the system without verifying the phases had actually disconnected you violated safe work procedures. In Canada you would have been written up with a violation and subject to a fine. I bet you didn't report the incident.

Considering, since electrical business was slow at the time, I was doubling as the Safety Co-ordinator - you're quite right. Just didn't believe the darn disconnects could seperate and leave one made. Lock-out does no good when the devices come apart.

You wrote "but the line to ground voltage on the 230 is only 120VAC." Which may be true for where you are, but its certainly not true for most of the world with 230VAC. Most 60Hz counties may have such a setup, but most 50Hz won't.

Therefore you must be more careful when making such statements as someone in a "true" 230VAC country may believe you - wrongly!!!

As you can see from the following map, more of the world's surface is true 230VAC than not.

You can see a better/clearer map online here:-

http://wikitravel.org/en/Electrical_systems

By the way, I would pick the voltage that is used by the "cheaper" machines.

This is a common complaint on this site that is not reflective of the post as it was worded. I was responding to the post as it was written, not to the whole world. The OP had a choice of 230V - 3 phase or 460V - last time I checked, if you have 230 V three phase, you can't have 230V to ground. Had he mentioned 240V, then I might have considered the antique systems in this country where there is a high leg. Had he not said three phase, then that also would have been a different response. My statement stands as written.

Your statement was simply wrong and very misleading, try reading it again and you will maybe understand why. It certainly did not apply to the original question.

But if you do not understand that, no problem as there are many here who do and who will apply corrections to any incorrect statement ANY OF US here make.....remember, nobody is perfect.

Don't get hot under the collar.....its simply not worth it!!!

Yes - it did refer to the original as JRaef and I we were discussing the safety of the voltage choices the original post concerned, and it was definitely 230V - three phase. Very obviously, if your system is 230V to ground, which is what you are concerned about, you are not going to have 120V to ground, now are you? To mimic one of the Gurus - if the reader is so unqualified to not realize that a 230V to neutral (ground) single phase system is not actually 120V to ground, then he shouldn't be working with electricity, should he? Perhaps you are concerned that some reader is going to say, well, this is only 120V why not touch it?

The real warning here should be to readers to NOT jump to one answer, but read the whole sequence of posts as they are relevant, aren't they?

It is actually quite easy to properly qualify a statement with regard to location for example, which would have allowed your original statement to stand as correct all on its own. Probably 3 or 4 extra words would have been enough....eg. not difficult.

If you are of the opinion that everyone needs to research back within a blog to check on the validity of a particular statement of yours, then so be it, but I have to completely disagree.

I for one would only do that accidentally (have done!), not intentionally.....I feel that each statement "must stand on its own two feet" as far as possible, so to say......not to need to search for separate support from other statements and/or people in other posts (in the case of CR4).....assuming of course where only a few words would have been needed, as in the case in question....

It was something I was shown/taught when learning IT in the Navy.....It has stood me in good stead with writing and giving training courses on various pieces of computer equipment over many years with several large US companies. It is simply because it makes the subject matter easier to both research on and to fully understand.....

If you are ever in a teaching situation, please reconsider your position on this matter. If you are already in such a position, the change is long overdue, your students will appreciate the changes......Best of luck and have a great day.

Teacher??? Not me - this is as close to dealing with people as they let me get - I deal very well with numbers and facts, but not well with people. (see my previous responses) Ever watch the Fox series "Bones" - well that's pretty close to me as far as understanding other folks and their ways.

They promoted a man over me to department co-ordinator at my suggestion to avoid direct contact with the customer. I find the problems in the job specs and interpret NEC issues with designs and he relays them to the customer.

Concerning the researching back - yes - that is a must in ALL blogs, as I myself have made the mistake, several times, of jumping into a statement in a blog only to find I was way off base as to what was being discussed. These things have a way of straying back and forth from the original subject, so if you only know how it started, you might not be in touch with the where the darn thing has headed since. Equivalent to reading the part of a set of directions you thik is pertinent to what you are doing without reading the whole set.

You get along well with lawyers - don't you?

You wrote:-

You get along well with lawyers - don't you?

Actually not, I have as little to do with lawyers as possible. Though it is difficult to avoid them completely....

To whit:-

"What is it when there are 50 dead lawyers lying on the sea bottom chained together?"

"A damn good start!"......

What I meant was your approach to totally explain everything in a response, and not assume the reader has followed the entire blog, sounds like the way to avoid a lawyer trapping you in a court case. Sounds like you have had experience with them. Or could it be an experience with a governmental regulatory agency? - they act a lot like lawyers.

No, never had such confrontations, maybe I was simply too good!!!!

What I neglected to mention was that the stuff I trained people on in the RN was mostly highly dangerous, Torpedoes, Mines, Cannons, small arms, Missiles, electricity, underwater diving equipment and the like......a failure of any sort could result in death or injury, as well as damage to a ship or submarine.......you learn pretty quickly how to teach in a manner that prevents as far as possible any accidents happening.....a methodical top down approach is fundamental.

I hasten to add, that for an armed service, the RN is well known for being one of the safest Navy Services in the world, though some accidents have happened over the many years its been around, but not on my watch, nor to people that I personally trained.....

I am sure that any ex forces people here will agree that it is as good as impossible to prevent all accidents!

Pick the cheaper machine - most motors in the area this is apparently being built are dual voltage now - same machine - wire the motor as desired for 230 or 460. Single voltage motors are going the way of the horse and buggy in the USA.

It does open up the second hand market for some things.......which over here for example will mean that the high voltage machines will usually be cheaper than standard mains voltage machines, simply because the "private" buyers will be looking at normal mains only possibilities.

Many forget this!!!

That chart only makes sense if you are pugging in consumer products. It makes no sense for industrial power.

More info about the motors would also help. Is this new equipment that will be to what ever voltage you choose. Or does the equipment already exist? What voltage was it ran on before? Because of the size of these motors and the numbers that's what I would choose to to set service voltage. Neither voltage is superior to the other in running the motors. At 440 you would only benefit from cost in wire to give it up to a transformer. That is if there is no other load that is not being disclosed. Like a large lighting load.

As far as safety most all operator controls are 120 v or less. If the equipment is properly installed and grounded there should not be and issue with either voltage.

Neither voltage is superior to other in running the motor.

That nails it for me, ozzb. As for the load there´ll be total of 70 FLA from three-phase prime movers, 50% expected service factor. Then about 40 FLA from one-phase consumers.

Did you remember to calculate your largest motor at 125%,as required by NEC?

(Refer to NEC article 670 for more details)

Sufficient capacity for starting motors?

Power factor of motors?

General lighting load?

Heat/cooling load?(The larger of the two)

In what capacity is your function on this project?

Also check your insurance premiums. In some parts of the world industrial sites are calculated on an inflated premium scale for having the higher voltage.

for flourescent and high intensity(mercury, sodium & multi-vapor) lighting it is common to use 277V (one leg of 460 to neutral) so most lighting won't need 120 and the transformer can be smaller.

You should also contact your power provider as some utility companies have "stand-by" charges that apply to industrial (480VAC) customers that do not apply to commercial (240VAC) customers.

In my area we pay a "base" load fee (regardles of equipment usage or not) and this is in addition to the standard KW useage charges as well as low power factor (a common issue with low loads) penalty fees.

The additional charges over a period of time is substantial.

If I am correct, installing a transformer to up your voltage to 460v would cost you money on your electric bill due to the inefficiency of the transformer. You would be paying 10-20% of your bill just for getting the higher voltage.

After all the comments, one thing occurs to me: You are going to need some standard voltage(for your area) convenience outlets. At some point some one is going to need a trouble light, radio, drill or something. If you go to the higher voltage for the motors and even HID lighting, you may eat up the savings in order to provide for these needs. Again, you are describing a fairly small load going in, so unless expansion is in the near future, or distances long enough to make voltage drop an issue, it seems that lower voltage would make more sense to me in your case. -- JHF

In CA PG&E uses 2 Xformers in an "open Delta" configuration to generate 230V 3phase. There is always an inbalance that can't be cured by "rolling the phases". 460V uses one Xformer and the phases are equal. Motors run cooler and last longer.

I always think of 460/3/60 as a distribution voltage to be stepped down as needed to power a motor. The advantage is the sizing of wire sizes, especially on long runs. Most Navy ships use 440/3/60 in order to manage the miles and miles of distribution needed. Smaller wire means less weight and ease of snaking it through wireways and around corners.