Electrical Advice, please

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Electrician Mike

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I am a licensed, bonded, insured electrical contractor. Give me a call. I would be more than happy to swing by and take a look at it for you and give you my recomendations. I tried to figure out what you had thru the posts, but too much to read, better/easier if I looked at it in person.
Mike
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Electrician Mike

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I am a licensed, bonded, insured electrical contractor. Give me a call. I would be more than happy to swing by and take a look at it for you and give you my recomendations. I tried to figure out what you had thru the posts, but too much to read, better/easier if I looked at it in person.
Mike
(918) 693-4361
 

Perplexed

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Thanks for the offer, Mike. I'll give you a call.

I keep reading your getting 40 amps at 240 volts, and 20 at 110, full load amps. Sure you haven't transposed those numbers? Ohms law never lies.

Dennis, the cutter I have switches automatically between 120V and 240V, depending on the incoming connection. As I understand it, on 120V the cutter (or welder) can pull around 27-28 amps at full load, which is the theoretical maximum amperage such a unit can pull using 120V. If the unit is running on 240V power, it can pull something like 45-48 amps at full load. I got all this from reading comments on a welding forum. Now if I'm wrong, please do correct me! :)
 

Shoot Summ

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Thanks for the offer, Mike. I'll give you a call.



Dennis, the cutter I have switches automatically between 120V and 240V, depending on the incoming connection. As I understand it, on 120V the cutter (or welder) can pull around 27-28 amps at full load, which is the theoretical maximum amperage such a unit can pull using 120V. If the unit is running on 240V power, it can pull something like 45-48 amps at full load. I got all this from reading comments on a welding forum. Now if I'm wrong, please do correct me! :)

It's unusual(very) for the load to go up with the voltage, typically the load drops. For example, the motor on my table saw draws 12.8A @115V or 6.4A at 230V.
 

Perplexed

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It's unusual(very) for the load to go up with the voltage, typically the load drops. For example, the motor on my table saw draws 12.8A @115V or 6.4A at 230V.

My apologies, I'm not expressing myself very well, and I should've re-read my old, dusty physics textbook before saying anything :P I do understand (well, kind of!) the nature of the relationship between voltage and amperage (I = V/R, aka Ohm's Law).

My plasma cutter is set up so that it can operate on either 120V or 240V, much like SS's table saw. However, the amperage draw can be adjusted via a "Output Current Control" knob to adjust for cutting through different thicknesses of metal. This knob is calibrated to run from 20 to 30 amps. The thicker the metal, the higher the knob is set (i.e., more amperage and less voltage). So if I'm reading Ohm's Law correctly, the cutter would actually have a higher maximum amperage draw at 120V than at 240V - right? If that's the case, then why do heavy-duty cutters (the kind that cut 1/2" or thicker metal), and welders, require a 240V supply?

I realize this is getting off on a tangent, but I'd like to get my facts straight.
 

TJay74

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I keep reading your getting 40 amps at 240 volts, and 20 at 110, full load amps. Sure you haven't transposed those numbers? Ohms law never lies.

I recently went through a similar process. I live in the sticks, but still had to get a permit and inspection, as we get our electric from Ponca City, and they won't put in a service unless its done that way.
Putting in the service is free for us, as long as the weather head, meter box, etc is installed and inspected.
You said everything is underground, so that makes it a little more difficult to see where the power is distributed. There is a down and dirty way, and I won't post it on the internet. Professionals can trace the line electronically.
Here is an Idea. Call OKIE and tell them you are going to dig in your yard, and the power company servicing your electric will come out and do it for free!



Just a FYI Okie does not makr private lines. They only mark the lines from the pole/transformer to the meter base. In his situation he has a cutover and Okie wont mark those lines. They can offer to mark them at the rate of $200 per hour and they dont put a promise on the accuracy of the markings.

just a FYI.
 

TJay74

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And SS is right, normally as long as the line size does not change when you increase voltage the amperage draw should drop. There should be a UL labs label on the welder with the 120v and 240v amps listed on it.
 

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So if I'm reading Ohm's Law correctly, the cutter would actually have a higher maximum amperage draw at 120V than at 240V - right? If that's the case, then why do heavy-duty cutters (the kind that cut 1/2" or thicker metal), and welders, require a 240V supply?

So they can operate at lower amperage.

That sounds like a smartypants answer, but I am being serious. The higher the amperage, the higher the current (the flow), and the (generally) more dangerous (and less efficient) things become, even if the voltage number is higher.
 

tyromeo55

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Current is not what makes a circuit dangerous. Think about it. A good truck battery can be rated well over 750 amps but because it is only 12 volts ( nominal) it can be handled with little caution. I'm on my phone now but when I get to a computer I can get into more detail if you like.
 

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I would be interested for clarification. I always thought it was current that was the danger (hence tasers and similar are high voltage, low current). I admit I am certainly no expert.
 

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