400 amp service

[Raccoon 3]

Iam installing a 400 amp service at a RV park using a 320 continous service meter socket. (2) #500mcm copper and (1) 350 neutral with a 1/0 ground wire to meter socket using a 2 1/2" rigid conduct. From meter socket to a 8"x8"x48" raceway where we will make taps for (2) 200 amp disconnects fuseible. Also a 100 breaker panel on raceway. The 200 amp disconnects feed existing panel in the park does this look right thank you .

 

[kbsparky]

What are your connected load calculations?

 

[Raccoon 3]

400 service

400 service

Its a private RV club with 25 RVs of assorted sizes calculated load 320 amps

 

[augie47]

RV

RV

I did a quick calculaton based on the 25 RVs from Art 551. Unless I made a math mistake your load calculations are way too low based on the requirements for 50 amp, 30 amp and 20 amp supplies.

 

[infinity]

So you're load is based on existing panel feeders? What is the #1/0 "ground wire" for?

 

[mdshunk]

Its a private RV club with 25 RVs of assorted sizes calculated load 320 amps

Yeah, I doubt that very much. 25 RV's is closer to 825 amps.

 

[kbsparky]

Yeah, I doubt that very much. 25 RV's is closer to 825 amps.

How in the world did you arrive at that figure?

My calculations using 551.71 and 551.73 came out to 490 Amps:

25 sites total

20% (5) required to be 50 Amp using 9600 VA = 48000 VA
50% (17.5 or 18) required to have 30 Amp using 3600 VA = 64800 VA
remaining sites (2) using 2400 VA per site = 4800 VA

Total: 117600 VA
@ 240 Volts = 490 Amps.

Using the demand factors allowable from table 551.73 (42%) I show a minimum required service of 206 Amps.

While I am not advocating installing the =minimum= allowable service (which should not be used in this case), specifying a 320/400 Amp service is well within the Code requirements.

Now, if the actual number of sites are using larger outlets (such as all of them with the 50 Amp receptacles) the totals will be different. This is the job of the electrician on site to determine when performing his load calculations, which I asked for in an earlier post in this thread.

 

[augie47]

RV

RV

kbsparkey, my stupid..I forget to apply the demand factors. And, I agree with you..this should not be the case here,,,,,in this area it is not unusual to find 90 to 100% occupany at our RV parks in the summer with most of them running air. I think the NEC is behind the times in its allowances for RVs

 

[mdshunk]

How in the world did you arrive at that figure?.

Two campgrounds as customers. The NEC falls way, way short in this area. Feel free to size the park service at Art. 551 if you want to. You just might not have happy customers.

 

[augie47]

Racoon3, For what it's worth I agree wholeheartedly with Marc. Installed a few, inspected many....there no way I would apply demand factors as liberal as the NEC shows. In my opinion, your sitaution appears that it would meet Code, but in this case I would not install anything where the sum of my overcurrent devices exceeded the cable ampacity.
Again..just one man's opinion.

 

[Raccoon 3]

400 amp service

The park is located in the green mountains of Vermont. I was at the camp this last summer during the hottest days I thing there were 6 campers with air on.Iam replacing a existing 200 amp service.Thank You

 

[mdshunk]

The park is located in the green mountains of Vermont. I was at the camp this last summer during the hottest days I thing there were 6 campers with air on.Iam replacing a existing 200 amp service.Thank You

With that very important historical data, which you just related, I agree with your approach.