Load Calculations at an RV park???

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juptonstone

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Lady Lake, FL
I was recently asked to modify the electrical distribution in a small portion of an RV park. Currently, they have a 200amp load center with 9 - 50 amp breakers feeding 9 slots. They want it modified so that they can meter the usage for each individual slot. I designed a RACK with two raintite gutters... one gutter feeds four meters and 50 amp disconnects. The other gutter feeds five meters and 50 amp disconnects. I had intended to use the existing 200 amp service as a JB so that we didn't have have to dig up allof the existing wiring. Now the county is requiring load calculations... however no one can figure out how to do load calculations for this job... They have RVs coming and going and only rarely are all nine solts in use simultaneously. Does anyone out there know how to perform a load calculation for this circumstance?
 
9600 VA per 50 amp outlet per 551.73

9 outlets gets a 55% demand factor per Table 551.73

9*9600=86,400 VA

86,400*.55=47,520 VA after demand factor.

47.520/240=198 amps.

Darn close to 200 amps ..... unless you have 3 phase.
 
I don't envy you. Having had to address these issues with two 'proven' customers, my first response is scream out "No Comprende" and run for the border!

Let me explain why ...

In technical terms, it goes far beyond sub-metering. Today's "RV" draws far, far more power than the ones in use when the park was designed. Air conditioning, full appliances, electric heating, even hot tube .... the days where you could assume that 30 amps of 120 was enough are long gone.

This means you're going to, sooner or later, have to close the park, dig up everything, and do it all over.

Meanwhile, your park owner is looking at ads in RV-park trade magazines offering meters and bases for $50. He can't understand why this work can't be done by his $8/hr. maintenance guy.

When you are done, and have left the site, he will then whisk in some of those fabled FEMA trailers (that he got at auction for $500), and ignore the 200-amp panels in them. Claiming to have 'improved' his park, he will then complain that you didn't give him enough power.

Start your pricing at $400 materials for just replacing the pedestal ... and be ready to lose the job. You'll be happier that way.
 
Thank You All!

Thank You All!

I appreciate the help with the calculations! The park is old and I do all of their electrical work.. This is the first time however, that I've had to re-do an entire section. I's always been one single site upgrade a at time before... E.G. upgrade a 30 amp/120v site to 50 amps/240v... Anyway... God only knows why, they tried a dozen different electricians before me and none of them either showed up, or they priced the work so high that it was unaffordable. The last guy they used before me, couldn't even get his work passed by the inspector (they wired a 100 amp park model to #6 USE that was 250' long underground!) The park liked our prices, our work was quality and we passed every inspection, so they've stuck with us and referred us to everyone they can!

I should note that they are aware that most of the wiring is sub-standard and will eventually need replacement. They are prepared for it and willing to pay to have it fixed... over time!

Again! Thanks for the help!

Jeff
 
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Use 9 of these.. meter at the point of use...
of course Midwest (I couldn't find a good pic of them) is the best for ease of assembly and disassembly. I've worked with Midwest, Milbank, and Cutler Hammer and Midwest is by far the best pedestal. Source of pic: http://www.sea.siemens.com/us/internet-dms/btlv/Residential/Residential/docs_Temporary%20Power%20Outlet%20Panel/Ped_Group_LG.jpg
Ped_Group_LG.jpg
 
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