50A RV OUTLET

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I believe that 551.46 (D) should cover the labeling. In it, it states 208Y/120 or 120/240- volt AC, 3-pole 4 wire.
From Reference.com:
NEMA 14
The NEMA 14 devices are four-wire grounding devices available in ratings from 15 A to 60 A. Of the straight-blade NEMA 14 devices, only the 14?30 and 14?50 are common. The 14?30 is used for electric clothes dryers and the 14?50 for electric cooking ranges. The voltage rating is 250 V. They are essentially the replacements for the NEMA 10 connectors above with the addition of a separate grounding connection.

All NEMA 14 devices offer two hots, a neutral and a ground, allowing for both 120 V and 240 V (or 120 V and 208 V if the supply system is three-phase rather than split phase). The 14?30 has a rating of 30 A and an L-shaped neutral blade. The 14?50 has a rating of 50 A and a straight neutral blade sized so that it will not fit in the slot of a 14?30.

NEMA 14?50 devices are frequently found in RV parks, since they are used for shore power connections of larger recreational vehicles. Also, it was formerly common for mobile homes to be connected to utility power via a 14?50 device.
 
The voltage rating of the plug and receptacle is not the issue.

I'm looking for a code reference that allows an RV that is labled 120/240v 1ph to be fed 120/208v circuit.

If the coach was labeled 120/208-240v there would be no question that it would be allowed.

Hey, maybe we've stumbled on to something,,,,,,,, does any one know if at the supply connection on the large coaches indicate 120/208-240v?

If that were the case the issue would be resolved.
 
I'd like to completely back peddle. There is a statement in the white book for the receptacle listings that allows 208v on a 250v Receptacle. It's not specifically talking about our topic but it does say you can use this receptacle for 208v motor applications. To me this is a solid confirmation this receptacle can be attached to a 120/208v system.
Also there is no such 120/208 single phase receptacle....

From the white book:
HORSEPOWER RATINGS FOR NEMA CONFIGURATION
RECEPTACLES
125/250v 1phase 3poles 4wire Nema# 14-50 3hp
NOTES:
L-L# - Motor connected line-to-line
% - Also suitable for 208 V motor applications at the indicated horsepower rating
 
551.44 Power-Supply Assembly.

Each recreational vehicle shall have only one of the main power-supply assemblies covered in 551.44(A) through (D).

(A) Fifteen-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(A) shall use a listed 15-ampere or larger main power-supply assembly.

(B) Twenty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(B) shall use a listed 20-ampere or larger main power-supply assembly.

(C) Thirty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(C) shall use a listed 30-ampere or larger main power-supply assembly.

(D) Fifty-Ampere Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(D) shall use a listed 50-ampere, 120/208?240-volt main power-supply assembly.

Please also see 551.42
 
jap said:
The voltage rating of the plug and receptacle is not the issue.

I'm looking for a code reference that allows an RV that is labled 120/240v 1ph to be fed 120/208v circuit.

If the coach was labeled 120/208-240v there would be no question that it would be allowed.

Hey, maybe we've stumbled on to something,,,,,,,, does any one know if at the supply connection on the large coaches indicate 120/208-240v?

If that were the case the issue would be resolved.
Click to expand...

this was never the issue for me. Whatever Jimbo wants to plug into his RV is of no concern to me. He really has to be responsible for that. I was only concerned that the premise wiring be correct.
 
marti smith said:
551.44 Power-Supply Assembly.

Each recreational vehicle shall have only one of the main power-supply assemblies covered in 551.44(A) through (D).

(A) Fifteen-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(A) shall use a listed 15-ampere or larger main power-supply assembly.

(B) Twenty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(B) shall use a listed 20-ampere or larger main power-supply assembly.

(C) Thirty-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(C) shall use a listed 30-ampere or larger main power-supply assembly.

(D) Fifty-Ampere Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(D) shall use a listed 50-ampere, 120/208?240-volt main power-supply assembly.

Please also see 551.42
Click to expand...

Again 551.42, and 551.44 are NOT talking about connecting an RV to shore power. It is talking about on-board equipment
 
jap said:
The voltage rating of the plug and receptacle is not the issue.

I'm looking for a code reference that allows an RV that is labled 120/240v 1ph to be fed 120/208v circuit.

If the coach was labeled 120/208-240v there would be no question that it would be allowed.

Hey, maybe we've stumbled on to something,,,,,,,, does any one know if at the supply connection on the large coaches indicate 120/208-240v?

If that were the case the issue would be resolved.
Click to expand...

The post I made earlier. Read 551.46 (D). It states that the RV shall be labeled... THIS CONNECTION IS FOR 208Y/120 or 120/240-VOLT AC, 3-POLE, 4-WIRE,
60 HZ,__AMPERE SUPPLY.
 
Between all of the following quoted articles, either 120/208 or 120/240 should be acceptable for both on board equipment as well as power supply equipment including the 14-50 plug and receptacle.

2008 NEC

551.40
(A) General Requirements. The electrical equipment and material of recreational vehicles indicated for connection to a wiring system rated 120 volts, nominal, 2-wire with equipment grounding conductor, or a wiring system rated 120/240 volts, nominal, 3-wire with equipment grounding conductor, shall be listed and installed in accordance with the requirements of Parts I, II, III, IV, and V of this article. Electrical equipment connected line-to-line shall have a voltage rating of 208–230 volts.
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551.42
(D) More Than Five Circuits Without a Listed Energy Management System. A 50-ampere, 120/208–240-volt power-supply assembly and a minimum 50-ampere-rated distribution panelboard shall be used where six or more circuits are employed. The load distribution shall ensure a reasonable current balance between phases.
Click to expand...

551.44
(D) Fifty-Ampere Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(D) shall use a listed 50-ampere, 120/208–240-volt main power-supply assembly.
Click to expand...

551.46(C)
(4) Units with 50-Ampere Power-Supply Assembly. Recreational vehicles having a power-supply assembly rated 50 amperes as permitted by 551.42(D) shall have a 3-pole, 4-wire grounding-type attachment plug rated 50 amperes, 125/250 volts, conforming to the configuration shown in Figure 551.46(C).
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Again 551.42, and 551.44 are NOT talking about connecting an RV to shore power. It is talking about on-board equipment
Click to expand...

If on board line to line equipment is required to be acceptable for 208 or 240 then what is the problem with feeding the receptacle with either voltage?
 
I dont see a problem installing 120/208v to the RV outlet as long as the manufacturers are required to install equipment that will accept either.

Thanks.
 
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