50 Amp questions

[gbkims]

A video on 120/240 service: 120V 240V Electricity explained - Split phase 3 wire https://www.youtube.com/watch?v=fJeRabV5hNU

[Skiddy]

The way I understand it, an RV is basically two 50 Amp services. That’s why it is often said a 50Amp RV can have 100Amps of load while a 30Amp RV can only have 30 amps of load. The excellent picture that shows 240V between the two hot leads and 120V between either hot lead and the neutral is the best. However, to my knowledge 0V measured between the two hot leads and 120V between either hot lead and the neutral will work just fine, provided there are no 240 V loads.
In other words a pedestal or home plug wired to support 240V loads is the best way to go, it will power your rig and a welder, dryer, oven some radial arm saws/table saws or other 240V loads.

[Overtaxed]

The way I understand it, an RV is basically two 50 Amp services. That’s why it is often said a 50Amp RV can have 100Amps of load while a 30Amp RV can only have 30 amps of load. The excellent picture that shows 240V between the two hot leads and 120V between either hot lead and the neutral is the best. However, to my knowledge 0V measured between the two hot leads and 120V between either hot lead and the neutral will work just fine, provided there are no 240 V loads.
In other words a pedestal or home plug wired to support 240V loads is the best way to go, it will power your rig and a welder, dryer, oven some radial arm saws/table saws or other 240V loads.

Well, 50A without a voltage doesn't tell you much (other than what gauge wire to use). 50A RV service CAN be viewed as 2 50A 110 circuits, but, most people call that "220V 50A service". All 220 lines have 110 available too (although you SHOULD NOT use it without a neutral line), just go from one plug blade to a ground, you get 110. Go between the plugs, you'll get 220. They are pulled from seperate "legs" on a breaker panel, so you get 220 volt (which why, in case anyone wondered, 220 breakers are bigger physically, it's not to carry more power, it's because they need to touch both poles to get 220V into a single breaker). Basically, inside every residential breaker box, there are 2 "hot" lines coming in from the power company. Both hots are 110V. If you put a volt meter from either hot to ground, you get 110. To both hots, you get 220. That's how you have both services in your house without transformers or stepping down the voltage, you're only pulling from one line.

And yes, 50A service CAN be seen as 2X50A 110V circuits, that's technically correct. It's also, in case anyone wondered, why you have SO MUCH more power on 50A service compared to 30A. 30A is 110V only, so about 3500 watts. Because 50A has both legs (or 220V service), you can get about 12,000 watts. It's roughy 4X as much power on a 50A RV service compared to 30A, again, explained by the fact that it's 220V service (double the wattage with the same amperage).

All this, while interesting, is probably too much detail. Go to Lowes, get a 220V 50A breaker that's the right one for your box (there are a lot of different kinds, take a picture of the inside of the box, they should tell you what you need in there) and 4 strands of 6 gauge wire. Wire strand one to "side one" of the plug and to the breaker, strand two to "side 2" of the plug and to the breaker. Then, the other two lines, run one to neutral and one to ground in the box (following the diagram). And your done.

[Skiddy]

Well, 50A without a voltage doesn't tell you much (other than what gauge wire to use). 50A RV service CAN be viewed as 2 50A 110 circuits, but, most people call that "220V 50A service". All 220 lines have 110 available too (although you SHOULD NOT use it without a neutral line), just go from one plug blade to a ground, you get 110. Go between the plugs, you'll get 220. They are pulled from seperate "legs" on a breaker panel, so you get 220 volt (which why, in case anyone wondered, 220 breakers are bigger physically, it's not to carry more power, it's because they need to touch both poles to get 220V into a single breaker). Basically, inside every residential breaker box, there are 2 "hot" lines coming in from the power company. Both hots are 110V. If you put a volt meter from either hot to ground, you get 110. To both hots, you get 220. That's how you have both services in your house without transformers or stepping down the voltage, you're only pulling from one line.

And yes, 50A service CAN be seen as 2X50A 110V circuits, that's technically correct. It's also, in case anyone wondered, why you have SO MUCH more power on 50A service compared to 30A. 30A is 110V only, so about 3500 watts. Because 50A has both legs (or 220V service), you can get about 12,000 watts. It's roughy 4X as much power on a 50A RV service compared to 30A, again, explained by the fact that it's 220V service (double the wattage with the same amperage).

All this, while interesting, is probably too much detail. Go to Lowes, get a 220V 50A breaker that's the right one for your box (there are a lot of different kinds, take a picture of the inside of the box, they should tell you what you need in there) and 4 strands of 6 gauge wire. Wire strand one to "side one" of the plug and to the breaker, strand two to "side 2" of the plug and to the breaker. Then, the other two lines, run one to neutral and one to ground in the box (following the diagram). And your done.

50 amp RV service is 2X50Amp 110V. Same as your home, although likely it is 2X100 or 2X200 AMP legs in two different phases, that’s why you get 220V. If you measure across the two bus bars in your home service panel you are measuring the potential difference between two feeds 180º out of phase. If you did not have any 220V, 2 X 110V at 180º phase difference appliances, your home would work just fine - same as your RV.

[Overtaxed]

50 amp RV service is 2X50Amp 110V. Same as your home, although likely it is 2X100 or 2X200 AMP legs in two different phases, that’s why you get 220V. If you measure across the two bus bars in your home service panel you are measuring the potential difference between two feeds 180º out of phase. If you did not have any 220V, 2 X 110V at 180º phase difference appliances, your home would work just fine - same as your RV.

Agreed, but most people, right or wrong, call that "50A 220 service". If you ask an electrician to wire up a 110 50A service using an RV plug, he's going to look at you like you have 2 heads. It's 220 service, the RV just takes it as 2 "legs" of 110 and doesn't ever use the 220 that's available by going from pole 1 to 2. Again, for the OP, look at the diagram that was posted, that's what you want. 110V from any leg to neutral or ground and 220 across the 2 legs. If you're getting an electrican to do it, tell him you need 50A 220 service with a neutral (4 prong). This is actually what I used for my install at home, if you hand this to an electrician who's even moderately qualified, he'll know what do with it:

https://www.amazon.com/Talon-LGP1S-E...=fsclp_pl_dp_1

[Jerryr]

Just a little but of info off topic. In the old days standard residential voltage was 110/220. Now the National Regulation steady state standard is 120/240v The targeted range is +-5% or 114-126v for 120 and 228-252v for 240v service.

If you’re interested here’s a good article to read. https://www.pge.com/includes/docs/pd..._tolerance.pdf

[offtohavasu]

That's funny Jerry. I was just going to say if you tell an electrician to wire up a 220 RV outlet, he'll still look at you like you have two heads. LOL

And on the breaker size, 50 amp 240v breakers being larger is not true. Yes it has to hit each phase, but they have split breakers that will work as well. What you get is 4 breakers (2 of which are tethered) in 2 slots.

[Jerryr]

That's funny Jerry. I was just going to say if you tell an electrician to wire up a 220 RV outlet, he'll still look at you like you have two heads. LOL

And on the breaker size, 50 amp 240v breakers being larger is not true. Yes it has to hit each phase, but they have split breakers that will work as well. What you get is 4 breakers (2 of which are tethered) in 2 slots.

Curtis,

Yep, here’s an example of a Quad, double pole 50 amp and 2-single pole 20 amp breakers for a Square-D Homeline box that only takes up 2 slots. I wish they had one for the QO breaker boxes.



I wish they had one for the Q0 breaker boxes so I could free up some space in my barn sub panel.

[offtohavasu]

Curtis,

Yep, here’s an example of a Quad, double pole 50 amp and 2-single pole 20 amp breakers for a Square-D Homeline box that only takes up 2 slots. I wish they had one for the QO breaker boxes.



I wish they had one for the Q0 breaker boxes so I could free up some space in my barn sub panel.

Siemens/Murray have the same