wire size for 50 amp service

Hi,

That is fine in theory--but I see much greater voltage drop than I'm comfortable with in real life on a 30 amp 50 foot #10 cord being fed from a 50 amp shore power supply. Fortunately, I've solved that issue with an autoformer.

However, I'd suggest trenching in the proper cable and adding a pedestal.

wnjj wrote:
If it's mainly to run the air conditioners, go with a smaller wire size like #8 with a 30A breaker. 2 legs of 30A should be plenty for that plus some other stuff. You really should never need a full 50A times 2 legs.

Running a hundred feet of 4 AWG cable above ground for several days is one thing. Having it lay there for weeks or months is quite another. A tripping hazard. Certain ultraviolet sunlight destruction. And last but not least doing this is a trifle to those who do not have to purchase a lot of # 4 THHN.

Don't know about where you live but in Sonoma county California, such a run of cable aboveground is a pricey code violation. The county fire department inspects and code enforcers have police backup. This is from January 2011, their lips to my ears.

The "way to do it" of course, is to not check, get fined, then do it according to code. Making a telephone call is, after all, exhausting.

happycamper002 wrote:

The usual tech term for dual phase is "two phase" which is derived from two totally separate power sources (i.e. two transformers, two generators etc.) ...no intermingling of the two power sources. This setup is common in industrial heavy demand load like 50-100 horsepower motors. Crushers for cement aggregate plants for example. Steel forging plants with those heavy hammers.

All legs of a motor physically have to be in phase (from the same source) for the load to stay balanced, and there is no NEC code section providing for seperate sources (seperate service) to intermingle, other than a few exceptions.

Even with 240 volt incoming service it still is considered single phase.

This installation is derived from one distribution transformer using mid connection between the two (240 volt) lines to get the 120-volt that splits the potential between the transformer winding, a split phase basically.

In order to get "dual phase" which by the way is not a term used by ANSI, NEMA IEEE. Instead ordinary Joe would call it Dual Phase.

The usual tech term for dual phase is "two phase" which is derived from two totally separate power sources (i.e. two transformers, two generators etc.) ...no intermingling of the two power sources. This setup is common in industrial heavy demand load like 50-100 horsepower motors. Crushers for cement aggregate plants for example. Steel forging plants with those heavy hammers.

In my effort to not appear being pedantic, I have no problem reading between the lines. . . at least (I try hard) because it gives me a good night's sleep. LOL

Confusing for some, but that's the way it's always been.

rhagfo wrote:

ScottG wrote:

rhagfo wrote:

ScottG wrote:

Tom/Barb wrote:
When we did our coach hook-up we ran 3 #4 cable RED/White/ and Black in hard conduit about 50 feet, We installed a 50 amp dual phase Circuit breaker in our master panel, then ran the conduit out thru the wall and attached it to the house, and ended at the Out door service box for the coach, enclosed is 4 way receptacle.
We also carry a 50' ready made 50 amp extension chord. It's some thing we thought we needed, but never use.

That would have been single, split phase service.

Cheers,
Scott

ScottG posted [COLOR=]dual phase 50 amp breaker, likely not inspected, as would be not code compliant without a GROUND!!!.

With a setup like this even if "Hard Conduit" metal with threaded couplings, I would not trust for a ground, unless one used bonded bushings at each end.

Wasn't me! Only one phase in use there.

My Bad read the quote line wrong it was Tom/Barb!

Yea, by the time there's this many quotes I've lost all track of who posted what. :o

ScottG wrote:

rhagfo wrote:

ScottG wrote:

Tom/Barb wrote:
When we did our coach hook-up we ran 3 #4 cable RED/White/ and Black in hard conduit about 50 feet, We installed a 50 amp dual phase Circuit breaker in our master panel, then ran the conduit out thru the wall and attached it to the house, and ended at the Out door service box for the coach, enclosed is 4 way receptacle.
We also carry a 50' ready made 50 amp extension chord. It's some thing we thought we needed, but never use.

That would have been single, split phase service.

Cheers,
Scott

ScottG posted [COLOR=]dual phase 50 amp breaker, likely not inspected, as would be not code compliant without a GROUND!!!.

With a setup like this even if "Hard Conduit" metal with threaded couplings, I would not trust for a ground, unless one used bonded bushings at each end.

Wasn't me! Only one phase in use there.

My Bad read the quote line wrong it was Tom/Barb!

If it's mainly to run the air conditioners, go with a smaller wire size like #8 with a 30A breaker. 2 legs of 30A should be plenty for that plus some other stuff. You really should never need a full 50A times 2 legs.

OP asked for wire size requirement, and it was provided.
Current draw might be ok on 50a extension cord (#6 wire) using Just the AC?
Check your A draw and V at the rig under your desired load... careful use might not demand anything more.... V @ +/- 10 percent.

rhagfo wrote:

ScottG wrote:

Tom/Barb wrote:
When we did our coach hook-up we ran 3 #4 cable RED/White/ and Black in hard conduit about 50 feet, We installed a 50 amp dual phase Circuit breaker in our master panel, then ran the conduit out thru the wall and attached it to the house, and ended at the Out door service box for the coach, enclosed is 4 way receptacle.
We also carry a 50' ready made 50 amp extension chord. It's some thing we thought we needed, but never use.

That would have been single, split phase service.

Cheers,
Scott

ScottG posted [COLOR=]dual phase 50 amp breaker, likely not inspected, as would be not code compliant without a GROUND!!!.

With a setup like this even if "Hard Conduit" metal with threaded couplings, I would not trust for a ground, unless one used bonded bushings at each end.

Wasn't me! Only one phase in use there.

ScottG wrote:

Tom/Barb wrote:
When we did our coach hook-up we ran 3 #4 cable RED/White/ and Black in hard conduit about 50 feet, We installed a 50 amp dual phase Circuit breaker in our master panel, then ran the conduit out thru the wall and attached it to the house, and ended at the Out door service box for the coach, enclosed is 4 way receptacle.
We also carry a 50' ready made 50 amp extension chord. It's some thing we thought we needed, but never use.

That would have been single, split phase service.

Cheers,
Scott

ScottG posted dual phase 50 amp breaker, likely not inspected, as would be not code compliant without a GROUND!!!.

With a setup like this even if "Hard Conduit" metal with threaded couplings, I would not trust for a ground, unless one used bonded bushings at each end.