Thats because your 30-amp RV outlet needs one neutral one hot and one ground wire to be connected properly as shown in this diagram. 122 for the washer.

How To Wire 220 Volt Outlet Diagram Dryer Outlet Outlet Wiring Breakers
If the dryer draws 40 amps you need to upgrade the wire to a beefier eight gauge.

What gauge wire for 30 amp dryer. But to extend it you must replace the entire run with 103 cable and a 30 amp breaker which is the standard dryer hook up. Youll notice that if you only have 208V you need 8 3. The size of the breaker you need to control the circuit is specified on the dryer label.
3-Prong 30 Amp Dryer Cord The Cable Matters 3-Prong 30A Dryer Appliance Cord is an essential replacement for an older dryer. The reality is that the rule of thumb is that you need a gauge wire size of 10 for 30 amps. If the existing wire is only 3 wire then you can not extend it.
That 10 wire is only supposed to carry 30 amps and its supposed to be protected by a 30-amp breaker. If its 30 amps which is common. Black Hot Red Hot White Neutral and Green Ground Most common for houses built after July 1 1996.
Product may vary by store. In general a circuit that runs 15 feet to reach the dryer requires larger wire. Wire Size Chart and Maximum Amp Ratings.
Compatible with most leading brand free-standing electric dryers with a 4-prong receptacle. If you have an electric dryer it must be on a dedicated 240-volt circuit. Check the documentation of your dryer for compatibility with a 3 prong dryer cord.
If yo uleave it you are fine. 30 amp 3-wire outlets are often found in buildings constructed before 1996. Longer runs may require an upgrade of wire size.
30 Amp 125-Volt250-Vault 3750-Watt7500-Watt capacity. Houseables Generator Cord 30 Amp 4 Prong Generators Extension 25 Ft 125-250v 7500 watt max Rating UL CUL NEMA L-14-30P Rubber 10 Gauge Heavy Duty L14-30 Transfer Power Cable Locking 103 49 32. This size breaker requires a minimum of a 10 gauge wire so this wire used would be a 102 with ground.
In fact its wired exactly the same way as your 15- or 20-amp home outlets are albeit with heavier 10-gauge wire instead of 14- or 12-gauge wiring. The minimum recommended wire size for clothes dryer circuits is 10 gauge. Heavy-Duty 7500 Watt Rated.
If your dryer does not require the neutral and is a pure 220V appliance than you can use the 10-2 and be code compliant. Now a 3-prong outlet is outdated from modern electrical codes but is accepted if you already have one in your home. How many amps can 12 gauge wire handle.
The wire size chart below shows allowable ampacities of insulated conductors rated up to and including 2000 Volts 60C through 90C 140F through 194F not more than three current-carrying conductors in raceway cable or earth directly buried based on ambient air temperature of 30C 86F. However amperage decreases over distance so appliance manufacturers advise a larger wire gauge for circuits that extend beyond a distance from their source. Electric Dryer Circuit Cable The typical cable used for a dryer circuit is 103 Type NM cable which has three insulated wires and a bare ground wire totaling four wires in all.
Typically a 220v30 amp Dryer circuit would utilize 103 with ground. Can 10 gauge wire handle 40 amps. Because a dryer runs on 240-volt power you need three-conductor cable to connect it to the panel.
Any circuit fused for 30 amps must use a minimum of 10 ga copper or 8 ga alu. Overcurrent protection different from ampacity cant be more than 15 amps for 14 copper wire 20 amps for 12 copper wire and 30 amps for 10 copper wire. Keep in mind that larger gauge numbers denote thinner wires and vice versa.
2404 D Bottom line. Cord clamp is provided to relieve strain on terminals. Simplify installation of your dryer with cording that meets the precise length and wire gauge requirements.
18 AWG 16 AWG 14 AWG 12 AWG 10 AWG 8 AWG 6 AWG 4 AWG 3 AWG 2 AWG 1 AWG 10 AWG 20 AWG 30 AWG 40 AWG 250 kcmil 300 kcmil 350 kcmil 400 kcmil 500 kcmil 600 kcmil 700 kcmil 750 kcmil 800 kcmil 900 kcmil 1000 kcmil 1250 kcmil 1500 kcmil 1750 kcmil 2000 kcmil. 10-Gauge wire with ring terminals. 103 is FINE for the dryer.
Wire Size for Dryer The wire size for a 30amp dryer circuit is 10AWG copper. Also can you wire a 10 2 dryer. As you can see from our rule of thumb section you will need a 8 gauge wire for 40 amps why a 10 AWG wire will not be able to handle this.
If your running a new circuit I highly recommend that you bring your outlet up to code and install a 4. If your dryer draws 30 amps like most dryers the dryer wire gauge is 10 gauge. The Wire Size for an Electric Dryer Circuit.
4-wire 6 ft 30 Amp cord. Enter maximum amps in circuit. In your case use at least 10 copper for your welder regardless how far it is from the breaker panel.
Clothes dryers require a relatively thick wire to accommodate their 30 amp circuit. This circuit originates from the breaker box containing a 2-pole 30 Amp breaker. According to this voltage drop table it looks like for 100 run you would want to up-size the wire to 8 copper to maintain voltage drop less than 3.
So yes you can use a 10 gauge wire for 30 amps but you cant use a 12 or 14 AWG for this amount of power as it simply cannot handle it. If its a 30 amp circuit and you have 240V to the house some dont and it should be tested then 10 3 with ground is OK.