Sample NEMA 14-50 Permit Application

[bollar]

All,

Here is a sample permit application, using 2011 NEC, that was approved by my municipality's building inspections department. I share this because I didn't have a good idea on what kind of package would be expected by the plans examiner and this was the result of my research online and calls to the examiner. I hope you'll find the format helpful, but you will want to confirm that your work complies with your local code, as well as the requirements from your local planning & inspections department.

 

[bollar]

FYI, I completed the project. It took me about two hours -- the biggest problem was actually dealing with corrosion in the load center -- the screws on the neutral and ground bars were frozen. Total cost was ~ $225, the bulk of which was the wire.

 

[FlasherZ]

Congratulations!

Is it a requirement that you submit the load calculation with the permit application? I have to say that's one of the more "thorough" (read: overly complex) permit application processes that I've seen. Normally, the inspector will be able to tell at a glance whether the proper load calculations were done at inspection time.

 

[bollar]

Congratulations!

Is it a requirement that you submit the load calculation with the permit application? I have to say that's one of the more "thorough" (read: overly complex) permit application processes that I've seen. Normally, the inspector will be able to tell at a glance whether the proper load calculations were done at inspection time.

Thank you!

I probably could have gotten away with not including the load calculations, but I had done the work -- originally to see if I could fit 100 Amps on one load center -- so it was easy enough to include. Since I don't do electrical work all the time, I thought it was important that I confirm I knew what changes I was making.

The inspector did say that my submission was better quality than most electricians would submit. They see so few owner-initiated permits here that I do think they are cautious.

BTW, the drawing and circuit/box schedule were the two items absolutely required. I think the inspector was most concerned that I was using AWG 6... That's what he spent the most time looking at.

 

[AudubonB]

Very, very nice.

I've been looking into learning how to perform load calcs. I can glean some insight through examining your chart, but have you an (internet) reference that gives leads?

Three questions:

1. Do your L & R 200A centers represent legs, or do they each have their own 120V + 120V legs? Load balancing is an extremely important task out here, given how the degree to which you balance will determine how happy (ie, long-lived) your generator is. Balancing is also important but a little less critical for inverters, given the miracles of modern electronics to rectify such imbalances.

2. Why is it that some rows sum to equal, and others do not? For example, you have general lighting at 12+ 10 = 3; remaining amps at 74 + 31 = 33; and 200A +200A = 320[400A TCEC]???

3. I recently was looking at a service panel that ostensibly was a 400A service, same as yours. RH side had only a 200A breaker; LH side had that breaker plus all the 20 - 100 A breakers. What does that configuration suggest?

Thanks!
Audie

 

[bollar]

I'll be happy to send you the spreadsheet -- just PM an email address.

For the questions:

1. The two load centers each have their own legs, so each 200 Amp load center is capable of doing 120 or 240 with the appropriate breaker.

2. General lighting doesn't foot because it's a shortcut. 3 represents 3 VA per square foot (3,953 * 3 = 11,859). Basically what I did then was take the total number of general lighting breakers (22) and allocate 11,859 by the number of GL breakers in each of the two panels.

The 200+200 don't tie because residential 400 Amp service is actually 320 continuous Amps at the meter -- at least here. I was testing to ensure that I wasn't breaking 320 in aggregate, or 200 on either of the load centers. I knew if either of those two happened, I'd need to learn a whole lot more about the NEC than I already know.

3. Without opening it up, I don't know. Maybe the RH side is unused? If there were any loads attached to it, I would have expected some sort of breaker.

 

[FlasherZ]

I've been looking into learning how to perform load calcs. I can glean some insight through examining your chart, but have you an (internet) reference that gives leads?

NEC is here and has the guidelines for load calculations.

1. Do your L & R 200A centers represent legs, or do they each have their own 120V + 120V legs? Load balancing is an extremely important task out here, given how the degree to which you balance will determine how happy (ie, long-lived) your generator is. Balancing is also important but a little less critical for inverters, given the miracles of modern electronics to rectify such imbalances.

Many residential 400A services installed today have 2 panels, each with a 200A main breaker, each fed with a set of service conductors that are rated for the main breaker. That's because anything bigger than 200A costs a LOT more. You do load calculations based on each panel @ a 200A rating (160A continuous max).

(Note: this is how we do it in many parts of the US. I believe mknox once told me that CEC requires a single disconnect rated at full load. The US permits multiple "service disconnects" in multiple panels provided that the sum of the service disconnects does not exceed the total meter rating.)

There is always a lot of confusion about the whole 200A vs. 320A question -- for some reason, the meter pans and boxes are called "320A" even though they're really rated at 400A (320A continuous, or 80%).

3. I recently was looking at a service panel that ostensibly was a 400A service, same as yours. RH side had only a 200A breaker; LH side had that breaker plus all the 20 - 100 A breakers. What does that configuration suggest?

Right side is for future expansion, everything was being served from the left panel. The breaker at the top (the big one) in both panels is the main breaker for that panel, everything beneath it goes through that breaker.

 

[AudubonB]

Thank you for your answers, gentlemen. Check your PMs.....