20 posts / 0 new
David

I understand that 240V appliances can operate with 50amps from both legs of a single phase, but most recreational vehicles do not have anything 240V. My original point.

And sorry for the misspelling of 'separate', sometimes I type too fast.

Ernie_Fergler
college student wrote:

I understand that 240V appliances can operate with 50amps from both legs of a single phase, but most recreational vehicles do not have anything 240V. My original point.

And sorry for the misspelling of 'separate', sometimes I type too fast.

I am still confused about those 240 volts you speak of. Where exactly are they coming from? If from a load center, than it would be two legs of 120 volts, correct? :confused:

Blake

Most RVs that are wired for 50 amps use each hot leg separately as two 120 volt circuits.

David
Blake wrote:

Most RVs that are wired for 50 amps use each hot leg separately as two 120 volt circuits.

I concur. Thank you.

Ernie_Fergler
college student wrote:

I concur. Thank you.

Now we are on the same page. Thanks !!!:D

sean132

I have been reading a book about home wiring and was wondering about 220 volt circuits. Do they not have a neutral? This book is very good showing 110 circuits, but not very clear on 220. I understand the 110 pretty well but I'm a little confused about how the circuit works with no neutral? Also it says that the grounds and neutrals should be on separate bus bars in the service panel, but in mine the grounds and neutrals are all on the same bar. Also, if i understand correctly a 110 circuit would use a single pole breaker and a 220 would use a double correct?? Thanks again for the advice and "education".

JLMCDANIEL

You take a transformer (A) wired so that the secondary windings output 240 volts, you add a wire connected to the middle of the windings (called center tap) Now you have a trans former that out puts 240 volts between the top and bottom leg and 120 volts between the center tap and either of the other two legs.

In residential wiring the center tap is referenced (by a physical connection) to ground. This grounded line is called the neutral line because it has a neutral voltage potential when compared to ground but it is a current carrying conductor.

In the main panel the ground bus and neutral bus are tied together either as a single bus or through a connection of both busses through the panel, On sub panels the bonding screw is removed and the neutral and ground are separate.

A 120 volt circuit only needs a single breaker because it only has one leg that is not referenced to ground. The 240 volt circuit uses 2 lines not reference to ground so if you only open one leg you could still get electrocuted by the other leg through your body to ground. That is why you need a double breaker.

Simplified answers but I hope it helps.

Jack

sean132

Thanks again for the explanations. I understand that if you use both legs you get 220, vs 110 from 1 leg and neutral. I just thought for 220 you had to use both legs and neutral. I am a mechanic, so I have a hard time because I try to compare my household wiring to dc wiring found in the machinery I work on. I am just trying to learn the basics of residential so that I can make simple repairs myself. I still think that for any major work Ill be better off calling a competent electrician.

JLMCDANIEL

OK Sean123,
You hook 2 12 volt batteries in series and get 24 volts but is you connect a third wire to the connection between the batteries you can get 12 volts from it to either of the other leads.
Jack

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