It is not an unsafe condition to make a 240 volt supply to your equipment. The reason for the no ground on the 240 volt drier circuit is simple, nothing used to utilize an equipment grounding conductor and equipment such as washers and driers all came equipped with a little extra green wire originating on the frame of the appliance with instructions to attach it to a water pipe at the appliance for safety grounding assurance. That is because the neutral on a clothes drier(Break)
Sidebar: USA lower 48 supplies residential dwellings with a 3 wire service drop to the point of attacthment consisting of 2 each insulated lines of a different phase and 1 each bare conductor which is technically called the grounded conductor. Either of the ungrounded conductors combined with the grounded conductor will reult in a potential of 120V nominal.
Use of the 2 ungrounded conductors without a grounded conductor connection will result in a 240v nominal potential.
Use of the 2 ungrounded as well as the grounded conductor will result in a supply called 120/240 so small things like timer motors etc. may be run from the lower voltage.
Now if you look at your overhead drop, you only see 2 conductors but upon closer inspection at your point of attachment at your riser you will see that the bare support(MESSENGER) wire has an electrical connection to an insulated conductor emerging from the weatherhead that is either white in color or physically modified either with tape, paint or other means to signify that that is the grounded service conductor for this installation. If you followed that wire to the pole, and have access to the line of poles, you will see that every couple or few poles there is a utility half round conduit running the length of the pole that carries a conductor from the grounded supply conductor up top to the earth into the hole with the pole. This creates the grounded reference for the system which transformers usually connect to at some point and without which the secondary voltages will do some pretty interesting acrobatics floating all over the place.
Do not confuse the equipment grounding conductor with the grounded conductor. They connect at only one place and that is at your service entrance to your house. The service entrance is where your meter receives its' feed fromk the service drop to your property, changing ownership at the service point(weatherhead splices). Coming in you have insul insul non insul(from them) and switches to 3 insulated on your equipment consisting of 2 ungrounded and one grounded conductor>AT THE SERVICE AND ONLY AT THE SERVICE AND NO WHERE ELSE IN ANY PANELS OR BOXES OR CONDUIT FITTINGS THE grounded conductor AND THE grounding electrode conductor AND THE equipment grounding conductors WILL BE BONDED TOGETHER BY MECHANICAL MEANS AND ALSO BONDED TO ALL METAL PARTS OF SAID EQUIPMENT.
The grounding electrode conductor runs from the service to a pair of grounding electrodes(In Calif it is the water pipe if metal within 5 feet of entry to the structure and considered your primary electrode. Here we also use a supplementry electrode most often in the form of a steel core copper clad rod of a minimum 1/2 diameter and 8 feet in contact with the earth.)
UNBREAK>>>
The Neutral as has become the slang, because it is anything but 1/2 of the time, the grounded conductor only bonds with the equipment grounding conductor at the service to keep the potential throughout the home distribution wiring to the point of use at a (0) ZERO potential so that if there is a an equipment failure of some sort where the body or case becomes energized there will be available a carpool lane so to speak with no cars in it at all unless it is an emergency and that emergency is there to be sacrafised so that you do not become the equipment grounded conductor or the return wire to earth.
Remember this is ac power, therefore inside a circuit 60 times a second for our grid that wire is of a different and opposite polarity. It is just following the magnetic rotation of the generator which is turning at some multiple of 60. That is the only generation frequency that I have experienced on land in the USA including Hawaii.
So a long story short, the dryer uses a 110volt motor and timer, and the heating element is 240 volt which is why the neutral is sometimes referred to as ground. And that works with the extra little green wire attacted to the water pipe. AND only if the feed for the dryer comes from the service entrance and NOT FROM A SUB PANEL. If it came from a sub panel (WHICH HAS A 4 WIRE FEEDER CONSISTING OF 2 UNGROUNDED CONDUCTORS AND A GROUNDED CONDUCTOR AND AN EQUIPMENT GROUNDING CONDUCTOR) and is hooked up with the neutral as ground also you have just crippled your safety ground in your sub panel by bypassing the dedicated emergency lane back to the service.
Realize, every time you utilize powel from an outlet, be it a light , appliance, plug, etc, anytime, as soon as you connect and energize equipment utilizing 120v that not so neutral conductor now has a 120 volts of potential on it. Don't believe me, want proof, don't recommend but pull the branch neutral for the circuit in question, whatever is energized will denergize and put your meter between that NOT SO NEUTRAL grounded condctor AND THE NEUTRAL BAR YOU JUST DISCONNECTED IT FROM. Be careful as that is a full 120 volts of flesh burning heart bursting potential. Touch it to ground accidentally and you will see that you also have an arc welder capable of instantaneous blinding metal melting if you are lucky light. Worse case is an ARC FLASH which is and arc welder melted metal propelled by a hand grenade and it will destroy most anything in its' path without the proper precautionary,protective, and safety equipment. And if too massive a destructive fault occurs, no amount of equipment will save you as it is akin to being at ground zero of a bomb exploding for a fraction of a second. Residential breakers are for the most part limited to 10,000 amps interupt ratingsd meaning the will break below that theoretically hopefully in less than, way less that one cycle,, or 1/60th of a second. The available fault current interrupt ratings on anyhthing seen for a home is usually 10,000 for the generic with 22,000 and 65,000 for some of the better poduct lines bordering on industrial such as the QO line. Other vendors have their equals.
THE BOTTOM LINE IS THIS, (proceed at you own risk and liability as we are not recomending you do this as I have no knowledge of your background, training, skills, or qualifications) If you want to safely use your dryer outlet to power your rework device, and it needs srtrictly a 240 volt supply the runs in to a transformer for the various required voltages demanded by the equipment. And there are only 3 conductors in the attachment cord to the unit. IE 2 blacks and a green, or black red and green, with no white or grounded conductor, and you do not need the outlet for an electric drier(ie you either do not have one or use a gas 120 volt model)BUT BY NO MEANS WILL USE AN ELECTRIC 240 DRIER UNTIL CIRCUIT IS RETURNED TO AS INSTALLED CAN IN THIS ORDER.
1) SHUT OFF 240 VOLT 30 AMP BREAKER AND DISCONNECT WIRES
2)TRACE RED AND BLACK WIRE BACK TO WHERE THEY EMERGE FROM CABLE
3)TAPE THE WHITE WIRE WITH GREEN TAPE AND MOVE TO THE EQUIPMENT
GROUNDING CONNECTION WITH THE OTHER BARE AND OR GREEN WIRES
4)GO TO THE RECEPTACLE, PULL THE COVER AND REMOVE THE ENTIRE
RECEPTACLE COMPLETELY
5)TAPE THE WHITE WIRE ALSO GREEN AT THIS END SO YOU NOW HAVE A
PAIR OF UNGROUNDED CONDUCTORS FOR 240 VOLTS AND A SAFETY VIA
A DEDICATED EQUIPMENT GROUNDING CONDUCTOR WHICH WILL GROUND
THE CASE OR CHASSIS DIRECTLY TO YOUR GROUNDING ELECTRODE DOWN
OUR CARPOOL LANE.
6) how safe do you want to be????????
The above will work and be safe only if your power connection remains capable of the carrying the available 30 amp current the breaker for your dryer was rated at. and do this up into your device to a pair of fuses to limit the current to an amount the device wiring and circuitry are constructed to withstand.
By utilizing several sections of the NEC you can arrive at the industry standard of any single utilization equipment load a circuit to a maximum of 80%. Your 16.5 amp device would therefore exceed this demand requiring a 25 amp breaker minimum. If it was 16 amps, use a 20 amp 2 pole (COMMON TRIP)240 VOLT BREAKER. {common TRIP}[CoMmOn tRiP] common trip common trip ...............
In te event of a fault it opens both legs simultaneously. I would recomment you install a different receptacle that did not include the 120/240 rating and was a 250 volt single phase 3 wire device so as to not inadvetently plug some other appliance in by accident.
Your number 10 wiring is adequate, and a 30 ampp breaker will work for the unit but unless there is a veryt high start up or surge current the overcurrent value is a bit high. BUT AS I STATED, IF YOU USE A 30 AMP CONNECTION ALL THE WAY TO THE DEVICE OVERCURRENT PROTECTION, IE FUSES THE FIRST CONNECTION OF THE INCOMING NUMBER 10-3 SO OR SOW CABLE, I WOULD RECDOMMEND A LOWER OVERCURRENT DEVICE.
tHE DRYER CONNECTIONS WERE A 10-30P AND A 10-30R WHICH WAS 125/250v 3pole 3wire connecting device.
You need to go to a straight 250 volt device as you no longer have the "neutral' only line times 2 and ground.
New non locking would require a 6-30P and a 6-30R or locking an L6-30P and L6-30R if you leave it at 30 amp breaker. If you change to 20 change the 30's to 20's ion the connector model numbers. Every voltage,# of poles,#of phases is different in the connectors as a safety standpoint protecting both the equipmnet, the premises, and oh yeah the most important one of all, The unskilled, and in some cases blatantly flirting with their life in this day of the dumbing down of America so everyone can feel good about themselves for being lazy leaches on society expecting a reward for nonperformance or personal effort.,,,,,, oops, sorry about that folks, just please
BE DAMNED CAREFUL BECAUSE ELECTRICITY IS LIKE A BOULDER BALANCED AT THE EDGE OF A CLIFF HELD IN PLACE BY A TOOTHPICK. NOT A NICE THICK REALLY GET IN THERE TOOTHPICK BUT ONE OF THE FLAT AT ONE END TO A POINT AT THE OTHER MADE FROM LEFT OVER SCRAPS AT THE PALLET FACTORY. IF YOUR NOT CAREFUL FASTER THAN YOU REALIZE OH SH.......YOU ARE DEAD.
If you can manage it, do it in the daylight at the panel with it deenergized, leave it disconnected until finished on the other end if you must turn power on for light, then go back and again deenergize the panel and reconnect and verify everything before buttoning things up.
Then test at the receptacle. You should get 120, 120, and 240 or something close when metering L1-G/L2-G/L1-L2 AND 0 G TO A WATER PIPE.
very last thing, Gas and water lines are usually bonded together most ofter at the water heater because the water line is your primary grounding electrode and it is a convenient place to jumper the 3 pipes and connect them with short wire(#6 bare solid copper, one piece) This is because of things like pumps, stoves, funaces etc that could energize those lines if there is a fault condition happening. Good luck and please please please exercise extreme caustion and as initially stated, kids, do not try this at home, it is a job for skilled professionals, and just because your card says engineer, that does maketh an electrician not. And all the book learning in the world will not save you if you touch the wrong piece of metal, even if you only touch it a little bit or for not very long. The NATIONAL FIRE PROTECTION ASSOCIATION issues an update to the NEC every three years for two reasons, to keep up with technology, and most importantly, becuase LIVES AND PROPERTY ARE STILL BEING DESTROYED BY THE MISUSE OR MISHANDLING OF ELECTRICITY IN THE FORM OF ELECTROCUTION AND FIRE.
I have witnessed dirt boiling, solid ground turn to boiling dirt from an electrical fault, high voltage shorts turn the atmosphere around you from orange to blue as air ionizes depending on the humidity and weather. AND IT WILL WILL WILL WILL TURN YOU INTO A BURNT INANIMATE OBJECT IF YOU GIVE IT EVEN ONE TEENY TINY MINISCULE CHANCE.
gloves, safety glasses, long sleeved heavy wool or flannel DRY shirt, jeans, (no officewear now fellas),and gals) rubber soled shoes,(hikers, athletic) and if it is wet out make a tent overhead and after it is up laydown plastic-wood-rubber mat in that order so that you may not advance to equipment grounding conductor today.
They are very much appreciated. I understand your answer Peter but I'd really like to actually understand rather than take it hehe. 