ECN Forum Forums General Topics of the Trade General Discussion Area Retail Plaza Service Size

Let's look at this the way an insurance company might.
That is, using the 'law of large numbers.'

Look at a few existing projects that are similar in size. See what sorts of tenant mix they have ... perhaps 2 'heavy' users, 3 'moderate,' and 7 'light.' See what their demand is ... perhaps the PoCo has some data. Perhaps up these figures by 10% for future growth, or an atypical mix.

Customer shopping your numbers? That's where you need to sell the value of your leg work.

Sure, the NEC wold allow you to use 3VA / sq. ft... giving you a 480v service of 100 amps .... but who are we kidding? Remeber what the NEC says about its' not being a design manual!

I'd visit existing, similar places at the busiest part of the day, and measure with an amp-clamp ... for a quick guess.
For a more exact estimate, I'd have to give the specific plans, knowing the tenants, a close going-over.

As luck would have it, our local news today announced the 'demolition date' of one of our shopping centers. This center, simply put, had been dying for 15 years. A large part of the reason was that the original utilities were grossly inadequate, with many, many 'band-aids' applied over the years. They simply could not serve the tenants that they wanted.

When I sign off on a set of calculations, I am saying 'this is my judgment.' I have to make the best guess I can. If some other fool, chasing the bottom dollar, wants to sign off on a marginal set of numbers .... well, that's his reputation, not mine.

15va x 15,000sf / 830v = 271a or a 400a HV

20va x 15,000sf / 830v = 361a is still a 400a HV service

We can even back into it and a 400a HV service is 22va/sf...

Just for grins, here are some real numbers from plans laying around in my office. I have a stack of about 100 more retail stores with what I suspect are similar numbers.

Banana Republic- 16w/sf
Old Navy- 12.3w/sf
Bicycle Sports Shop- 9.5w/sf
SunglassHut 12.5w/sf
Bombay Clothing- 15.5w/sf
Ann Taylors- 13w/sf
Talbots- 20w/sf

Recent strip mall, utility service at each end; 14 stores. 800, 3 phase, 208 at each end. 200 amp to each space. All were plain vanilla boxes; 8-2x4 fluor; 6 recept, 3 exit combos, 5 gal wtr heater, bath exhaust fan/lite, 3 ton HVAC (gas heat), sign circuit, rear wallpack light.
Tenants; Subway, Krauzers, Cleaners, Furniture, Indian Rest., Dollar store, Nail Salon.....and yes, a Tanning Salon. The Salon was increased to 400 amp, 208.

Other ones I have worked at (larger store spaces) had 400 A, 480 each, out of 2k switchgear.

John

The owner wants 480V. How would you set up the service for a house meter and provision for tenant meters?

That gets a lot trickier. One meter will need to feed a 480V panelboard that feeds a transformer that feeds a 120V panelboard to deal with the Owner's 480V and 120V house power.
The other meters will feed the tenants who will likely want strictly 120/208V for their stores. Most POCO rules don't want a transformer on their side of the meter, so each Tenant will end up with a transformer...

If you can't change the Owner's mind about the 480V, see if you can get the POCO to give you (2) Service drops...480V and 120V.
That way there are no transformers to mess up the layouts, since most Tenants are very defensive about losing square footage for anything that doesn't add to their bottom line.

I think the owner is set on providing 480V period. The only advantage I see to the owner is a lower cost for the secondary to th building. Did I mention that the service will be on the out side of the building. I have never seen a 480V service for this small of a building so I am not picturing how this would be set up for tenant meters (as opposed to just a current transformare cabinet for one meter).

It’s not difficult or tricky, and is pretty much a preferred method in my neck of the woods.

You furnish:
Primary Conduit and pole riser or manhole penetration; pull string only.
T-Pad w/grounding
Secondary Conduit and Wire
Main Disconnect (local critera may apply here, if its less than 6 handles this is not required in some areas)
CT Can
Meter Can
Tap Box (unless you’re AJH will let you do taps in the gutter)
Tap Blocks
Gutter that is long enough to accommodate all the tenants meters
House Meter Can
277/480V House Panel (100A 12-24ckt) For building lighting, signs, and lots lights.
9kVA Transformer
120/208 House Panel (100A 12-24ckt) For Receptacles, heat trace and misc.
(Note: you can do a powerzone 120/208V panel with a transformer built in but they can be hard to get and are expensive)

All the tenant meters are HV glass meters in a can, they come out of the gutter into a disconnect, to a meter (some areas hit the meter first then a disconnect) then to the lease space to disconnect or a MCB panel depending on your local criteria.

Depending on the deal you make, either you or the tenants furnish the service to the lease space and each space gets their own transformer and who furnished the lease space service is also negotiable. This is all SOP for tenant finish out, and most tenants especially national chains want HV service.

Not sure how the POCO works up there but getting a HV and a LV service to the same building does not happen here.

I would think for this size the 25w/sq ft is about right. This size would probable accomodate 3-5 tenants, all of which probably aren't tanning or food. The standard 100A retail should balance it out. Much larger spaces go down (w/spft) because of divesification; smaller goes up in demand, CYA. Plus, figure your exterior lighting, probably 100A @ 3ph 480 w/ small low voltage. Service to a gutter w/ taps - it's prelim.

I just looked at a few buildings here in town. While these were commercial/industrial rentals .... the typical tenant has a two room office in front, with a warehouse / shop / garage taking up the bulk of the space, I really liked the way the service was set up.

(Total building volume was about 22,000 sq ft, with each space maybe 1700 sq ft on average).
There was an electric room, which held a meter and disconnect for each unit.
Within each unit, there was a 480 panel, a transformer, and a 208/120 panel. Everything was surface mounted, so access was easy.