Autoformer

pianotuna wrote:
Hi Dutch,

NEC covers NO plug in devices.

Dutch_12078 wrote:
Don, I don't think "Autotransformers shall not be used." exempts portable units from the prohibition for RV use.

Then the NEC should have nothing to say about RV's at all. They're all "plug in devices"... ;)

Hi Dutch,

NEC covers NO plug in devices.

Dutch_12078 wrote:
Don, I don't think "Autotransformers shall not be used." exempts portable units from the prohibition for RV use.

pianotuna wrote:
Hi Dutch,

NEC prohibits hard wired autoformers in RV's but when the unit is a plug in device, they are not prohibited. This argues for having a plug in unit. I choose to do plug in rather than hard wired.

Dutch_12078 wrote:
Be aware that some parks ban the use of "autoformers" (autotransformers), either out of ignorance, believing that they somehow "steal" power, or because either they or their insurance carrier are aware that the NEC prohibits their use in RV's. If nothing else, that could be a factor in deciding between a portable unit versus a built-in one that's out of sight.

The NEC is none to clear on the details, so I may well be interpreting it incorrectly, but I believe the prohibition is specifically on using an autotransformer in the converter, presumably to ensure that the 12V and the 120V systems are isolated from each other. The section on which the prohibition is listed is dealing with requirements for having separately derived electrical systems in an RV, i.e. the 12V system and the 120V system.

Note in this case "autotransformer" refers generically to a transformer in which the primary and secondary partly share the same winding, and not solely to the voltage correcting transformers used with RVs (which are indeed generally built as autotransformers).

pianotuna wrote:
Hi Dutch,

NEC prohibits hard wired autoformers in RV's but when the unit is a plug in device, they are not prohibited. This argues for having a plug in unit. I choose to do plug in rather than hard wired.

Dutch_12078 wrote:
Be aware that some parks ban the use of "autoformers" (autotransformers), either out of ignorance, believing that they somehow "steal" power, or because either they or their insurance carrier are aware that the NEC prohibits their use in RV's. If nothing else, that could be a factor in deciding between a portable unit versus a built-in one that's out of sight.

Don, I don't think "Autotransformers shall not be used." exempts portable units from the prohibition for RV use.

Hi Dutch,

NEC prohibits hard wired autoformers in RV's but when the unit is a plug in device, they are not prohibited. This argues for having a plug in unit. I choose to do plug in rather than hard wired.

Dutch_12078 wrote:
Be aware that some parks ban the use of "autoformers" (autotransformers), either out of ignorance, believing that they somehow "steal" power, or because either they or their insurance carrier are aware that the NEC prohibits their use in RV's. If nothing else, that could be a factor in deciding between a portable unit versus a built-in one that's out of sight.

MrWizard wrote:

usersmanual wrote:

MrWizard wrote:
yes it would help

i dont use hookups often, and haven't had 50amp hookup in the past 4yrs

but i have never had low voltage on 50amp, on the occasions i used it

I think your mistaken here; most rv parks have 50amp outlet and a 30amp one. the power supply comes from the same source so if u meter each part of the 50 amp out and the one from the 30 amp they should(will) have the identical voltage supply

i would not know about most RV parks
i am NOT there
like i said, my experience ... never had low voltage on the few times i had a 50 amp hookup

If you are unfortunate enough be where it seems everyone wants to use electric heat and not buy LP, then yes maybe you have experienced problems

again not germaine to the OP question
his question was can he use it on 30 amps will it hurt

not a question about low voltage on 50, he like you and others, has a need for it on 50amp, or it would NOT be in his RV

i have NOT needed one
yes i have thought about 'maybe someday'

yes sorry when I read things over today I must have misunderstood the intention of your post because I can really cant make sense of what I said in relation to what u said. I had a Hillary moment LOL

usersmanual wrote:

MrWizard wrote:
yes it would help

i dont use hookups often, and haven't had 50amp hookup in the past 4yrs

but i have never had low voltage on 50amp, on the occasions i used it

I think your mistaken here; most rv parks have 50amp outlet and a 30amp one. the power supply comes from the same source so if u meter each part of the 50 amp out and the one from the 30 amp they should(will) have the identical voltage supply

i would not know about most RV parks
i am NOT there
like i said, my experience ... never had low voltage on the few times i had a 50 amp hookup

If you are unfortunate enough be where it seems everyone wants to use electric heat and not buy LP, then yes maybe you have experienced problems

again not germaine to the OP question
his question was can he use it on 30 amps will it hurt

not a question about low voltage on 50, he like you and others, has a need for it on 50amp, or it would NOT be in his RV

i have NOT needed one
yes i have thought about 'maybe someday'

Be aware that some parks ban the use of "autoformers" (autotransformers), either out of ignorance, believing that they somehow "steal" power, or because either they or their insurance carrier are aware that the NEC prohibits their use in RV's. If nothing else, that could be a factor in deciding between a portable unit versus a built-in one that's out of sight.

Hi,

Go to Mexico. I got a 4000 va unit for use with my 30 amp RV for $230.00 Cdn (173.xx usd) It has 3 layers of boost (110, 100, 90) and 1 layer of buck (135).

ArchHoagland wrote:
Speaking of Autoformers...what is a ballpark price for one, installed?

around $500 for 50 amp but u don't install per say there a plug and play at least the ones Iam familiar with work that way