220.87 - WA State

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charlie b

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Lockport, IL
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Does anyone from around these here parts know if LNI has established an amount of load that you can add to an existing building without having to perform the calculation described in 220.87? What I mean is this: If I wanted to add 36 amps to an 800 amp board (i.e., under 5%), do I need to do a 30 day load measurement? This is not a facility that would require a plan review, and is not in a major city that has its own local rules.
 
Does anyone from around these here parts know if LNI has established an amount of load that you can add to an existing building without having to perform the calculation described in 220.87? What I mean is this: If I wanted to add 36 amps to an 800 amp board (i.e., under 5%), do I need to do a 30 day load measurement? This is not a facility that would require a plan review, and is not in a major city that has its own local rules.

There are no exceptions or modifications to 220.87 from the WAC or RCW that I have found. In reality you would be surprised at how many times I have loads 30 amps or more added to panels without any calculations done to see the existing capacity of the panel. To be honest and just dealing from hands on experience, adding less than a 5% load on a panel has never caused any issues that I have seen, especially if you know that have proper OCP for the panel and feeders. I would just add the load and not worry about it.
 

charlie b

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Lockport, IL
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One of my co-workers brought out that section as well. It only applies to schools, jails, and hospitals, buildings that require a plan review before the permit will be issued. My project is not one of those types of facilities.

We are setting up a 30 day load study to begin sometime next week. But my mechanical counterpart wants to be able to add a set of fans (36 amps total), without my load study slowing down the installation. I was just looking for options. If timing gets tight, I'll see what the local authorities will allow.

Thanks for the assistance.
 

jumper

Senior Member
One of my co-workers brought out that section as well. It only applies to schools, jails, and hospitals, buildings that require a plan review before the permit will be issued. My project is not one of those types of facilities.

We are setting up a 30 day load study to begin sometime next week. But my mechanical counterpart wants to be able to add a set of fans (36 amps total), without my load study slowing down the installation. I was just looking for options. If timing gets tight, I'll see what the local authorities will allow.

Thanks for the assistance.

Okay, but I did find this in section 3A. Might help as a starter. I missed it before.
You have a 800 amp supply so it misses on that account, but who knows-ya might skate.

(3) Electrical plan review.

(a) Electrical plan review is not required for:

(i) Lighting specific projects that result in an electrical load reduction on each feeder involved in the project;

(ii) Low voltage systems;

(iii) Modifications to existing electrical installations where all of the following conditions are met:

• Service or distribution equipment involved is rated not more than 400 amperes and does not exceed 250 volts;

• Does not involve emergency systems other than listed unit equipment per NEC 700.12(F);

• Does not involve branch circuits or feeders of an essential electrical system as defined in NEC 517.2; and

• Service and feeder load calculations are increased by 5% or less.
 
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charlie b

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Lockport, IL
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Retired Electrical Engineer
Again Jumper, that section has to do with whether or not a plan review is needed. I already know that I won't need a plan review. The EC will be able to pull an electrical permit for this project, without my first having to get the AHJ to review, and accept, my drawings. The question is, when it comes time for the inspector to pass judgment on the completed installation, will I be asked to produce a calculation that proves that the added load did not cause any panel to become overloaded, and if so, will it be enough for me to simply say that this was a very small load addition? Not having found a way to avoid doing a 30-day load study, I am going to the site tomorrow to get that study started.

By the way, this site is not in Seattle, and the utility metering does not provide peak demand data. So the 30-day measurements are my only option.

Thanks again to everyone for your assistance.
 

necnotevenclose

Senior Member
Charlie,

My experiance with LnI in recent years is that if the added load is more than 5% of the metered or design load (existing engineers panel schedules) plan review is required.
 
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