Service Load calculation

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Veepelectric

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Recently I did a load calculation on a 7 unit strip mall. Power is 120/240v single phase. Each unit (1800 square ft.)will have a 200 amp panel. None of the occupants are known. Codebook says that the service should be sized to the load served. I used 7 x 200 = 1400a + 100a landlord panel x .8 = 1200a total. Any comments or suggestions?
 
Re: Service Load calculation

Chances are that your service will be well oversized. The method for determing total load can be found using Article 220. Just because the unit panels are 200-amperes, that doesn't mean that is the load to be served in each unit. Perform a service/feeder calculation to determine service size.
 
Re: Service Load calculation

This really is a tough situation. If you don?t know who the tenants will be, nor what types of equipment each will need, then how do you perform an Article 220 calculation? I suppose one way would be to use ?typical? values for other occupants of other strip malls. But the method you used, to presume that each panel will be loaded to 80 % of its rating, is far more than is needed (as Bryan has pointed out).

So the key question seems to me to be, ?How do you handle a core and shell service, when no information is known about the prospective tenant build-outs??

Any ideas?
 
Re: Service Load calculation

I had this same situation in a commercial office building. The spaces hadn't been rented yet, and we designed the shell.

Then in moves a health spa. They cut out part of the concrete floor and installed an exercise pool. They had 2 x 30kw hot water heaters for showers, whirlpools, laundry, etc, a 50kw heater for the pool, another 20kw steam generator for a "steam bath", 5hp pumps for the pools.....not to mention the HVAC needed to suck up all the water evaporating from the pool.

Things like that you just can't plan for.

STeve
 
Re: Service Load calculation

It is not up to the new tenant to negotiate with the owner for any costs associated with upgrading the service? Should not the contractor installing the tenant improvement be responsible for verifying the adequacy of the service, and for including any upgrade in the project costs? Or am I being naive? :D
 
Re: Service Load calculation

After some of the units we have done recently, I thought I would err on the side of caution. I don't need a lawsuit down the road. Some of the tenant work we have recently done includes a tanning salon, laundramat, Dentist office, quilt shop, dry cleaner and coffee shop. I was amazed at the load these units carried. HVAC, lighting and HW calculated to 90a per unit before tenants added anything.
 
Re: Service Load calculation

New to forum. I don't think that it should be the contractor's responsibility to size for unknowns or for future expansion. ( tenants that open tanning salons or other high energy consumming businesses). Owner's or GC's precieve a conflict of interest when an electrician wants to over-size. I looked at a job not long ago where the owner keeps saying that the EC screwed him ( service to building too small ). This was a warehouse and he's trying to use it for industrial use ( Large machines ). After talking to the engineers at the power company I found that everyone had suggested that size for at least 5 years of expansion and not the minimum.
 
Re: Service Load calculation

Agree that service most likely will be oversized a good bit but your suggestion is resaonable considering lack of knowledge of loads. Simular experience (6 units - one known~calculated service 200 amp, 1 ph.) Suggested installation of flexible metering/disconnect arrangement with svc. ent. to 4 units being installed as needed in the future. Owner said no - 200 amp to each now as each unit would always be small retail~ see often a good renter wanting to lease mutiple units with one meter will show up and the renter will have to accept the greater cost for changes.
 
Re: Service Load calculation

In my opinion as designer it is very important to have very good communication with the owner in a case such as this. We are the professionals and we are in a possition to make an educated decision, but in the end the owner will be paying for the job and end up using whatever we design. I would inform the owner about the pro's and con's of "correctly"(since we don't exactly know the loads) sizing or oversizing. We must make it clear that in the end it willl directly affect him/her.

If we "guesstimate" and a potential ocupant needs more capacity, and the owner tells the potential occupant that the capacity improvments are at their cost, that potential ocupant might go look else where....so the bottom line is that in cases such as this, communication is very important with the owner. Part of our job is to look after the best interest of our customer.
 
Re: Service Load calculation

It seems to me that your best bet is to have a heart-to-heart with the owner and explain the options he has. Explain what the minimum requirements and costs would be versus what might be needed if someone who uses a lot more juice comes in would require. This is really a business decision, and should be made by the business owner, because it involves intangibles that you really can't properly evaluate.

He may feel that having adequate juice for any forseeable tenant is a desirable feature and worth paying for up front, or he may feel that a tenant who needs a bigger service should pay to upgrade. In either case, he should make the decision based on being fully informed of his options by you.
 
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