Retail service sizing, optional calculation method

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shroominator

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Can anyone point me to the correct section of 1999 NEC for an optional method of calculating feeder and service size for a retail application?

Article 220 seems to cover everything but retail or commercial. This is for a furniture store full of track lighting, which based on the 150va per 2 feet rule, is blowing an 800A existing service out the window. Actual track head installation will be 50% of calculated load or less.

Any help is appreciated, as always.

Craig
 
Re: Retail service sizing, optional calculation method

I don't see an optional method for a furniture store.
 
Re: Retail service sizing, optional calculation method

Sorry to say, but there is none. The best I can offer is to use several sections of track, instead of one long track, to cut down on the total length.
 
Re: Retail service sizing, optional calculation method

Shroominator try NEC 1999 Example No.D3. Store Building and Table 220-3(a), and if you can post more info regarding the project electrical system we can most likely help out.
 
Re: Retail service sizing, optional calculation method

800 amps is a lot of power. Is this an existing store being remolded? Existing demand? How many sq feet in the store? How many ft of track?
Voltage? I assume the service is 3 phase.

[ July 11, 2003, 08:57 PM: Message edited by: bob ]
 
Re: Retail service sizing, optional calculation method

Sorry, but I wasn't ignoring anyone or neglecting my post. The system didn't notify me when someone replied to my question, so I thought nobody had.

Here's the info.

This is a shell bulding in which the furniture store is tenant finish.

Approx. 16,500 sq. ft.

The space is served with an existing 800A, 120/208V, 3ph, 4W distribution panel with 800A main circuit breaker. This is `MDP'.

Load breakdown is as follows:

Three existing rooftop units:

`RTU-1' = 108A MCA on 150A breaker.
`RTU-2' = 108A MCA on 150A breaker.
`RTU-3' = 69.6A MCA on 90A breaker.

Here are the loads I am adding.

Track lighting = 361.4A @ 208V, 3ph (load calculated using NEC Article 220-12(b)).

General lighting (fluorescent troffers, some downlights) = 37.8A @ 208V, 3ph.

Receptacles = 84.8A @ 208V, 3ph.

Two water heaters, 1500W ea. = 8.3A @ 208V, 3ph.

This totals to 777.9A @ 208V, 3ph which is well above the 80% limit of `MDP'.

That's all.

I have utilized existing breakers at `MDP' to feed four 120/208V, 3ph, 4W panelboards as follows:

Panel `L1' = 100A, MLO from 100A C/B.
Panel `L2' = 225A, MLO from 225A C/B.
Panel `L3' = 225A, MLO from 225A C/B.
Panel `L4' = 225A, MLO from 225A C/B.

There you have it. I appreciate any input you can give whether good, bad or indifferent.

If push comes to shove, I can only force the lighting designer to trim down the amount of track.

Thanks again,

Craig

P.S. If you need any further info, you should probably private message me because the system is not notifying me when someone replies to my message.
 
Re: Retail service sizing, optional calculation method

Table 220.3A does not show an Occupancy as you have described. I used 3 va/sq ft + 1 va for rec.
Actual for A/C units are as follows

`RTU-1' = 108A MCA /1.25 = 85
`RTU-2' = 108A MCA /1.25 = 85
`RTU-3' = 69.6A MCA /1.25 = 56
Total = 226 amps
General Lts = 4va x 16500 sqft= 66000 va =183 amps
Track lts per your post = 361 amps
Water heater load = 9 amps
Total = 226 + 183 + 361 + 9 = 779 amps
This is the caculated load. The 80% does not apply. Unless you have other load the 800 amp main would be adequate.

[ July 17, 2003, 04:49 PM: Message edited by: bob ]
 
Re: Retail service sizing, optional calculation method

Where is this located?
Does your lighting designer have to comply with the IECC (which only allows 1.9W of Lighting per sq.ft.for Retail Sales). This would only allow you 31.35KW of lighting loads. There are other exemptions and allowances you can utilize in these calculations, but I don't believe they will ever add up to 143KW or 8.7W/sq.ft.) of Lighting.
If you can figure a way to do that, The lighting designers I work with would Love to meet you. :D
 
Re: Retail service sizing, optional calculation method

This project is in Independence, MO. Pretty much anything goes as far as lighting is concerned. No Title 24 like in California. They just look for a safe and NEC compliant installation for the most part. It is out for plan review now. Will see what happens & let everyone know. Again, the system is not notifying me of posts, so sorry for the delay in response.


Originally posted by plechtenberg:
Where is this located?
Does your lighting designer have to comply with the IECC (which only allows 1.9W of Lighting per sq.ft.for Retail Sales). This would only allow you 31.35KW of lighting loads. There are other exemptions and allowances you can utilize in these calculations, but I don't believe they will ever add up to 143KW or 8.7W/sq.ft.) of Lighting.
If you can figure a way to do that, The lighting designers I work with would Love to meet you. :D
Click to expand...
 
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