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

They come in different colors. They are color coded like transistors. Look at the fuses.

Bill

-- Ferme le Bush

When computing service load the 120v stuff ends up being half of it's amps, assuming you balance the load across the 2 phases

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.

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

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.

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

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.

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?"'

$50,000 x # of hoops jumped through / # of days to deadline :-)

Ben Miller

Finally a decent estimating tool.

Hire this man, he is a wizard

does #of hoops include AF* (aggravation factor) ?

On Fri, 07 Apr 2006 20:51:30 -0700 Paul Hovnanian P.E. wrote: | 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.