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Old 08-10-2022, 09:09 AM   #21
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Thanks rucker I would think all the 50 amps are 240 as you stated., but have never hooked up to one. I only used a single outlet for a heating blanket once while camping in TN. What a life saver that was. Dropped to 10f that night and we were set to camp in GA in 60 degree weather.

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Old 08-10-2022, 09:13 AM   #22
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so.......

question for the experts

if i have a 240 appliance with no neutral, what happens when i power both sides of the circuit with the same phase (as in a 30-50 dogbone)?

either the smoke comes out or nothing at all
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Old 08-10-2022, 09:21 AM   #23
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Neutral. Do I need it?

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Originally Posted by turf View Post
so.......

question for the experts

if i have a 240 appliance with no neutral, what happens when i power both sides of the circuit with the same phase (as in a 30-50 dogbone)?

either the smoke comes out or nothing at all
------------------
Just like a standard water heater. Closed circuit.

Many (all?) of the newer hospital surgical units do the same with 120v by using an isolated transformer which supplies two 60v legs and a ground. No neutral. Instruments still receive 120v.


Oven & range elements typically do not require a neutral, either. The neutral is provided for the 120v digital display, lights, convection, timer/clock....
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Old 08-10-2022, 09:30 AM   #24
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so, as long as there is a load, the circuit flows? regardless of phase?

my bus was professionally wired until i got it.

it was setup to run off the generator, full split phase 50amp, household wiring, balanced loads.

i added the shore connection and now can plug into campground 50a.

once i got stuck at a 30a service only park and my gen was forbidden. i cooked at another bus and left the next day.

i have a 30-50 dogbone and chickened out using it because of my wiring.
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Old 08-10-2022, 11:00 AM   #25
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Quote:
Originally Posted by turf View Post
so.......

question for the experts

if i have a 240 appliance with no neutral, what happens when i power both sides of the circuit with the same phase (as in a 30-50 dogbone)?

either the smoke comes out or nothing at all
I'd say nothing will happen. Both legs being from the same source, it wouldn't have any phase difference, and without the phase difference between the 2 legs it won't have voltage and shouldn't even turn on. But what do I know.

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Oven & range elements typically do not require a neutral, either. The neutral is provided for the 120v digital display, lights, convection, timer/clock....
I thought most of that stuff would be 240v in a 240v appliance? I guess if the appliance requires a neutral it could be 120, but IDK of any of my 240v home appliances having a neutral at them.
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Old 08-10-2022, 02:33 PM   #26
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I'd say nothing will happen. Both legs being from the same source, it wouldn't have any phase difference, and without the phase difference between the 2 legs it won't have voltage and shouldn't even turn on. But what do I know.
I'd agree. I'd it put this way: with no neutral there is no return path for that one hot leg connected to both sides of the 240 volt appliance. There is 240 volt potential but it goes nowhere. A properly wired 240 uses the other leg as neutral for the return path. They take turns being hot and neutral at the rate of 60 hertz.

The wire is still very hot!!! Your electronic controls may light up and work because they run on 120, and all that juice is available on BOTH sides of the device and all over in the appliance wherever the 240 volt lines run, just looking for a path back.

Quote:
I thought most of that stuff would be 240v in a 240v appliance? I guess if the appliance requires a neutral it could be 120, but IDK of any of my 240v home appliances having a neutral at them.
This is another wicked important point you raise, for those of us building skoolies and 'repurposing' stuff. It's unrelated to the use of a 50-30 dogbone, but worth mentioning here since we are talking 240 volts in general.

Using an older 3 wire 240 volt appliance on a bus increases shock hazard if that appliance is not well grounded to the bus chassis, and that chassis is in turn not well grounded back to the pedestal or shore power source. 3 wire appliances may use one leg of the power for 120 volts, like for the motor or electronics, and complete that circuit with [gasp] the ground wire! Old school knob and tube, practically.

If your older, 240 volt, 3-wire appliance has electric controls, that is very definitely a possibility. In a skoolie you're at much greater risk of shock or lighting up your chassis if that ground path isn't excellent.

Recommendation: unless you know for sure they don't have 120 volt internal circuits using ground as a neutral, don't use 3 wire 240 on a bus. They are old school, and all newer (4 wire) appliances are inherently safer.

I'd love to hear from folks who have more experience with 240 volt appliances and how they've dealt with them, things like water heaters, dryers, AC units...
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Old 08-10-2022, 02:45 PM   #27
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Quote:
Originally Posted by turf View Post
so.......

question for the experts

if i have a 240 appliance with no neutral, what happens when i power both sides of the circuit with the same phase (as in a 30-50 dogbone)?

either the smoke comes out or nothing at all

My guess would be nada, as the circuit would not be completed. No out of phase leg or neutral to complete the circuit
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