50 amp to 30 amp adapter

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

CA Traveler wrote:
The 50A RV circuit is 120/240V 50A and it does indeed supply both 120V and 240V to the RV.

Most RVs don't have 240V appliances but some do. But for the technically inclined it is NOT just 2 120V circuits. Rather it's a split phase design such that the neutral carries the difference in amps of the two hots and hence cannot exceed 50A. The circuit is identical to a home 50A oven for example.

The above as written could suggest to some that "50 amp RV service" can only handle a maximum load of 50 amps when in fact it's 100 amp service across 2 out of phase legs with a common neutral, offering 12,000 watts of power vs just 6000 watts for a true single phase 50 amp service, 3600 watts for single phase 30 amp service, 2400 watts for single phase 20 amp service, and 1800 watts for single phase 15 amp service. Ideally this so-called 50 amp service will be installed in any coach so the anticipated loads will be somewhat balanced - e.g. with dual A/Cs one will be wired across the hot and neutral of one leg, the second A/C across the hot and neutral of the second leg. Any suggestion that this service offers a maximum load capability of just 50 amps (6000 watts) is simply incorrect.

CA Traveler wrote:
The circuit is identical to a home 50A oven for example.

It's also identical to a 100 or 200 amp main panel in a house, except it's only 50 amps.

CavemanCharlie wrote:

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

.

Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

The 50A RV circuit is 120/240V 50A and it does indeed supply both 120V and 240V to the RV.

Most RVs don't have 240V appliances but some do. But for the technically inclined it is NOT just 2 120V circuits. Rather it's a split phase design such that the neutral carries the difference in amps of the two hots and hence cannot exceed 50A. The circuit is identical to a home 50A oven for example.

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

You are. So-called "50 amp RV service" is actually 100 amp service across two 120 vac legs which when measured from hot to hot measures 240 vac. Any rig wired with "50 amp service" is wired so part of the load will be on one 120 vac leg and part on the other 120 vac leg. In large rigs that may be equipped with a washer & dryer the dryer may be wired across both legs or 240 vac just as it would be in your home.

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

.

Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

myredracer wrote:

Stovepipe wrote:

myredracer wrote:
Don't forget to always turn the pedestal breaker off before you plug in.

Just out of curiosity, why?

If you plug in live, there are capacitors in the converter/charger circuitry that cause a high momentary inrush current. You can hear a zap and in the dark you can see a flash. The zap causes pitting on your shore power plug blades and inside a pedestal recept. The pitting attracts dirt and eventually there is poor contact causing heat and possibly a meltdown. You can clean up a plug, but there's nothing you can do about pedestal recepts. and they just get worse and worse over time. If your plug blades look dirty or discolored, clean them up with some fine grit sandpaper.

I've seen some newer pedestals with a label on them to turn power off first. No shock hazard.

Great information, thank you.

And turn the breaker off before unplugging. It's also safer just in case you get in contact with the prongs or it's wet. Many many sites we've been in tend to have damp ground near the pedestal.

Stovepipe wrote:

myredracer wrote:
Don't forget to always turn the pedestal breaker off before you plug in.

Just out of curiosity, why?

If you plug in live, there are capacitors in the converter/charger circuitry that cause a high momentary inrush current. You can hear a zap and in the dark you can see a flash. The zap causes pitting on your shore power plug blades and inside a pedestal recept. The pitting attracts dirt and eventually there is poor contact causing heat and possibly a meltdown. You can clean up a plug, but there's nothing you can do about pedestal recepts. and they just get worse and worse over time. If your plug blades look dirty or discolored, clean them up with some fine grit sandpaper.

I've seen some newer pedestals with a label on them to turn power off first. No shock hazard.

In the beginning, I used to plug our TT in at home with a couple of light gauge 15 amp extension cords. I had one connector & plug go up in smoke and melt one day because I was not turning the power off first. I ended up install a 30 amp recept. in the carport along with a disconnect switch beside it.

krsmitty wrote:
Can get a spark/ voltage spike...what I have been told any way.

Well I will certainly turn it off before plugging in going forward just to be safe. I wonder if such a spark could translate into a shock?

Can get a spark/ voltage spike...what I have been told any way.