Is there a difference between amps at 120v and amps at 240v?

I'm putting together a load sheet for our public utility and I'm
collecting up all the devices that consume electricity and making a
table that shows each device. In NJ JCP&L uses what is called a load
sheet which is in my opinion wholly inadequate to develop the necessary
amps required for a property. An example is they ask what is the
largest horsepower pump that will be used. Well for our projects,
their may be a half dozen pumps, up to 15 A/C compressors etc. We do
big projects, the one I'm working on will most likely require 3000 amps
and JCP&L is not sure how to deal with this other than to say 3 phase.
Of course 3 phase is about 5 miles away, so we have to think outside
the box.
My question is this.
When listing the equipment and it's amperage (which is being provided
by the individual contractors), is an amp always an amp? What I mean
is if I have an A/C condenser rated at 24 amps and I know that device
is a 240 volt device does that have any special meaning to the public
utility? Or does it mean that if it were a 120v device it would have
been 48 amps?
My HVAC contractor has given me a list of equipment mixed 120 and 240
volt that adds up to 826 amps. Do I need to be concerned as to whether
it is 120 or 240? The electrician has installed a 1200 amp service for
the main house, but he has also installed an additional 800 amps in
seperate panels in two out buildings. We are currently fighting with
JCP&L that the 167KVA transformer is wholly insufficient. My
understanding is that a 167 gives 600-800 usable amps and that it may
be able to operate up to 1000 amps.
Our determinations are that we will need 1,200 amps for the house, 800
for the outbuildings, another 1,000 for the outside pumps, ponds,
irrigation, site lighting etc and another 800 amps for a large 24 stall
barn which will be installed. This gives a potential for 3,800 amps
total based on paper. Now I know that JCP&L does a calculation whereby
they know that full amperage draw will never happen, BUT in these large
scale residential properties (31,000 sq ft) It is possible that at
times (Parties), that most of this equipment is running. We are no
longer living in a "dont' have something plugged into every outlet
environment" It would happen that all 15 HVAC zones are running during
a large gala while the pond aeirators and fountains and pool and
jazuzzi pumps and significant lighting are all operational at one time.
JCP&L needs to understand this.
So, is an amp an amp when it comes to these calculations?
Thanks for your help. Oh, don't worry, I'm not trying to replace good
engineering practices, I'm just trying to make sure that my electrician
and power utility are taking everything into consideration. They still
make all the calls, I just need to be an enlightened GC.
Reply to
Roveer
Loading thread data ...
On 4/5/06 2:48 PM, in article snipped-for-privacy@i39g2000cwa.googlegroups.com, "Roveer" wrote:
They come in different colors. They are color coded like transistors. Look at the fuses.
Bill -- Ferme le Bush
Reply to
Salmon Egg
When computing service load the 120v stuff ends up being half of it's amps, assuming you balance the load across the 2 phases
Reply to
gfretwell
an amp is always an amp.... but: good practice is to divide up the 120 volt loads between avalible circuits.
assuming you single phase circuit is exactly ballanced, add up the 240 loads then 1/2 of all the 120 loads. (you have to facor in motor starting currents and consider the possibility if multiple simultaneous starts as in the event of a brief power intruption)
P= e * i * (pf)
see first reply
We are currently fighting with
you electrition/contractor should have had this completely organized before installing the first wire.
price out the differance between running a third wire for five miles and sufficient generator power to run the parties. heres a hint: at todays prices a brand name 100KW generator w/xfer switch + parts & labor costs about $36K to $38K (USD) fuel is extra.
sound like you have the wiring completed already. converting to 3 phase panels will be costly.
it sounds very much like its late in the project to worrying over this. what does the architect say? who designed the AC? (no answer needed - i think you are asking the wrong folks)
was this a design-build type project? (shudder)
it doesn't sound to me like you will sleep easy until you have hired an independent architect or master electrician to review the situation.
Reply to
TimPerry
For a system that size: 1) If you didn't have a licensed electrical engineer design the system, you should; and 2) I would think the utility would send an engineer to meet with your electrical engineer and discuss all of those things.
The utility load sheets are all very simplified. It gives them the numbers that they need to size transformers and lines. Don't compare the transformer rating with your installed capacity. They use rules of thimb and diversity factors, and your service size is also based on diversity, all of which results in a lot of "fudge factor". You would be surprised how low the amp draw is on a typical service. As others have said, split the 120 loads evenly, add the 240 loads, give them the motor information, and whatever else they ask for. Be sure to indicate the continuous and non-continuous loads. I would also mention special load conditions that you know about, as you have stated above, especially simultaneous equipment operation, frequent motor starting, etc.
If this sounds overwhelming, see number 1 above. A professional engineer would be able to help you through all of this with very little trouble.
Ben Miller
Reply to
Ben Miller
I would think the best thing to do would be have an electrician temporary install a watt meter on the service that graphs the load demands over a period of time.
Reply to
Terry
He seems to have disappeared since I suggested the same thing. He probably wants to save money. I guess he doesn't know that consultants have three different rates...
1 Normal work, doing it right the first time - competetive 2 Emergency, gotta have it now, fixing it after it is FUBAR - premium 3 Forensic, investigating the cause of the electrical fire - expensive!
Ben Miller
Reply to
Ben Miller
A 3000 Amp motor? That's either a typo, or this is a project for which some serious engineering expertise is required. Expertise well beyond the 'is there a difference between 120V and 240V' point.
Reply to
Paul Hovnanian P.E.
Do you have a rate for: 'Some unqualified person bid the job and now the customer and/or state authorities are starting to ask questions. Like, "Where is your license?"'
Reply to
Paul Hovnanian P.E.
| Roveer wrote: |> |> I'm putting together a load sheet for our public utility and I'm |> collecting up all the devices that consume electricity and making a |> table that shows each device. In NJ JCP&L uses what is called a load |> sheet which is in my opinion wholly inadequate to develop the necessary |> amps required for a property. An example is they ask what is the |> largest horsepower pump that will be used. Well for our projects, |> their may be a half dozen pumps, up to 15 A/C compressors etc. We do |> big projects, the one I'm working on will most likely require 3000 amps |> and JCP&L is not sure how to deal with this other than to say 3 phase. |> Of course 3 phase is about 5 miles away, so we have to think outside |> the box. | | A 3000 Amp motor? That's either a typo, or this is a project for which | some serious engineering expertise is required. Expertise well beyond | the 'is there a difference between 120V and 240V' point.
Hopefully he didn't mean 3000 amps all in _one_ motor. Otherwise, that really should be done in some higher voltage, maybe as much as 2400. But he wouldn't qualified to mess with 2400 volts (or 3000 amps) and neither would I.
He probably needs to be thinking in kVA and then translate to amps.
And he probably needs to get building service at 480Y/277 or 600Y/347.
Reply to
phil-news-nospam

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