max current for RV pedestals?

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sliderule

Member
Location
Langley, BC
RVs are covered under art. 551 and the required allowance per 30 amp RV site is 3600 VA (and then there's the allowed derating for multiple sites on a feeder or for a service). I take this to mean that a 30 amp 120 volt RV can draw up to 30 amps continuously without having to derate anything to 80%?

A standard molded case breaker is designed to operate at up to it's rating for an indefinite period. But I believe there is a temp. limitation for breakers in an enclosure per UL 489 that may reduce it's continuous rating?

So the question is, is there anything that means that a 30 amp RV cannot or should not draw 30 amp continuously from an RV pedestal?

The thing is, there really is no way for an RV owner to monitor/control/limit their loads to 80% of the pedestal breaker rating anyway. Many 30 amp RV owners are operating 2 AC units plus other loads that are taxing a 30 amp breaker to the max for long periods of time.

The panels in RVs also have a 30 amp (1-pole) main breaker (or 2-pole 50 amps for a 50 amp RV) so I guess the same question would apply there too.

Thanks!
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
The key may be in the definition of "continuous load". Even though the pedestal may be loaded to the hilt, in a 3 hour period there is going to be some equipment cycle often enough for the load to be considered non-continuous.
The NEC has taken into account that "roughing-it" now often includes HVAC units and increased the load calculations on 50 amp RV spots from 9600 va to 12000 va.
 

sliderule

Member
Location
Langley, BC
RVs are covered under art. 551 and the required allowance per 30 amp RV site is 3600 VA (and then there's the allowed derating for multiple sites on a feeder or for a service). I take this to mean that a 30 amp 120 volt RV can draw up to 30 amps continuously without having to derate anything to 80%?

A standard molded case breaker is designed to operate at up to it's rating for an indefinite period. But I believe there is a temp. limitation for breakers in an enclosure per UL 489 that may reduce it's continuous rating?

So the question is, is there anything that means that a 30 amp RV cannot or should not draw 30 amp continuously from an RV pedestal?

The thing is, there really is no way for an RV owner to monitor/control/limit their loads to 80% of the pedestal breaker rating anyway. Many 30 amp RV owners are operating 2 AC units plus other loads that are taxing a 30 amp breaker to the max for long periods of time.

The panels in RVs also have a 30 amp (1-pole) main breaker (or 2-pole 50 amps for a 50 amp RV) so I guess the same question would apply there too.

Thanks!
Rvs are a unique situation of their own it seems. In the summer, many often run 2 AC units all day long plus other loads and will be at or near 30 amps for way more than 3 hours. Then there's a plethora of 50 amp RVs nowadays and they routinely plug into a 30 amp pedestal with an adapter and they will draw more compared to what a 30 amp RV will. Or course, with so many RVs drawing so much in the summer, voltage drop often becomes a significant issue (and some will use autotransformers).

I haven't looked at the applicable UL standards in a long time. Is a single 30 amp (or 50 amp) breaker in a pedestal considered to the be the same as a main breaker in a panel which can have up to 42 branch breakers below it? A pedestal enclosure has a lot more volume inside compared to a cramped panel and I think a breaker wouldn't get as warm/hot?
 

keith gigabyte

Senior Member
Rvs are a unique situation of their own it seems. In the summer, many often run 2 AC units all day long plus other loads and will be at or near 30 amps for way more than 3 hours. Then there's a plethora of 50 amp RVs nowadays and they routinely plug into a 30 amp pedestal with an adapter and they will draw more compared to what a 30 amp RV will. Or course, with so many RVs drawing so much in the summer, voltage drop often becomes a significant issue (and some will use autotransformers).

I haven't looked at the applicable UL standards in a long time. Is a single 30 amp (or 50 amp) breaker in a pedestal considered to the be the same as a main breaker in a panel which can have up to 42 branch breakers below it? A pedestal enclosure has a lot more volume inside compared to a cramped panel and I think a breaker wouldn't get as warm/hot?


I have had several campers in the last 20 years. My current one is a 2016 coachman 1 ac unit. It is set up for 30 amp from the factory. If you run the ac and micro at same time it ALWAYS trips the pedestal breaker. I tonged it one day out of curiosity..ac mic and inverter all running together..35 amps..figure that one out..
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I wonder about these type of manufacturers, whether they actually follow any NEC standards or really just love to push the envelope in engineering.
 
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