Load Calcuation Commercial Help ?

[wawireguy]

Commerical lighting is considered continuous and subject to a 125% multiplier. It's obscure. Some snippet in a section that continous loads are subject to 125%. I think I'll crunch these numbers for fun today and see what I get.

 

[augie47]

Commerical lighting is considered continuous and subject to a 125% multiplier. It's obscure. Some snippet in a section that continous loads are subject to 125%. I think I'll crunch these numbers for fun today and see what I get.

This is true, but I don't think it plays a direct part in Art 220 when using Table 220.12.
Look at the example mentioned (D-3 pg 765 in '08) and you will see they compared the actual load (8500 watts) to the Table 220.12 calculated load (without the 125%) and selected the largest.
(T 220.12 is a "not less than number which in the OPs situation, is a lot larger than his actual load x 1.25)

 

[wawireguy]

I took a look at that also.. My MH book shows you applying the 125% demand to the load calculated off 220.12. I thought I understood this part now I'm not so sure.. Crunch the numbers and gitter done.

 

[augie47]

On what did you base your HVAC amperage ? (MCA, FLA, etc)

When I use the "raw" numbers and Art 220, I come out with a number slighly less than your 150 amps service, but with the high % of 120 volt loads it's going to be difficult to distribute it equally.

If you can distribute the loads evenly on the 150 amp panel, considering load diversity and the fact that your actual lighting load is less than the T 220 .12 load, you might get by with the existing 150 amp.
Were it my customer, I would want to make sure they knew it was a close call. If they are looking for a "low bid", I'd go with existing.

Take into account my numbers might be incorrect

 

[Part-Time]

Look at this and tell me what you think.
i agree the chiller amps is high. not sure why that is
is is basically a big refrigerator the holds flowers.
runs all the time to keep flowers fresh.

6 Receptacle Load noncontinuous 220.14( I ) at 180 VA 1080 VA
2411 General light load table 220.12 sqft X 3 VA X 1.25 9028 VA
10 "Track lighting in addition to General lighting 220.43 ( B )
continuous load at 125% 5 Four Foot track light assemblies." 1875 VA
2 "Sign or Outline Lighting Outlets 220.14( F ), 600.5 ( A )
continuous load at 125% Two outside outlets " 6000 VA
1 "All other continuous loads at 125%
One small appliance Chiller" 6000 VA


Total Calculated Load (less HVAC) 23983 VA


HVAC Load:
1 "Air Conditioning Load @ 100% (Volts X Amps = Watts)
One 240v 35amp AC omitted rarely used.
13.4 x 120 = 1608 x 1.25 = 2010 VA Condenser
40 x 240 = 9600 x 1.25 = 12000 VA 7.5 ton AC Unit 14010 VA
HEAT-Furnace/Air Handler Load (Volts X Amps = Watts) 0 VA
Total HVAC Load 14010 VA


Total General Load + Total HVAC Load 23983 +14010 37993 VA

37993 / 240 = 158.30 amps

 

[augie47]

Go for it.
I do still contend, however, when using T 220.12, or 220.43(B) the 125% is not necessary.
Nor is it required for your HVAC.

 

[Volta]

Commerical lighting is considered continuous and subject to a 125% multiplier. It's obscure. Some snippet in a section that continous loads are subject to 125%. I think I'll crunch these numbers for fun today and see what I get.

I don't think you will find anyting in the NEC's 9 chapters that will say that directly. Now I expect the maximum load of a lighting outlet to continue for three hours, and that is all that is needed to call it continuous. But I expect the same in a residence. Happens all the time.

This is true, but I don't think it plays a direct part in Art 220 when using Table 220.12.
Look at the example mentioned (D-3 pg 765 in '08) and you will see they compared the actual load (8500 watts) to the Table 220.12 calculated load (without the 125%) and selected the largest.
(T 220.12 is a "not less than number which in the OPs situation, is a lot larger than his actual load x 1.25)

Did you see, though, that the example would take 125% of the larger of either lighting load? I maintain that it is not Code, but still . . .

... a big refrigerator the holds flowers.
runs all the time to keep flowers fresh...

One 240v 35amp AC omitted rarely used...

To me, you can omit the 240v 35amp AC by not connecting it. Otherwise, "rarely used" is not good enough. Cool temperatures are not just a creature comfort here, they increases the time the store can hold stock. Be sure that they will use the 35 Amp A/C whenever they feel they need it- if installed. Gets warm where you are .

 

[RETRAINDAILY]

I was looking around and ran it to this written by the man himself-)

http://ecmweb.com/mag/electric_commercial_load_calculations/

 

[Volta]

I was looking around and ran it to this written by the man himself-)

http://ecmweb.com/mag/electric_commercial_load_calculations/

Yup, he (Mike Holt) wrote:

... Assume the general lighting load for commercial occupancies other than guestrooms of motels, hotels, hospitals, and storage warehouses is continuous. Calculate it at 125% of the general lighting load listed in Table 220.3(A)...

Notice that he said "assume". Some buildings might have areas wherein the lighting load is not expected to continue for three hours. Think of occupancy detectors. They are not only used in bathrooms, but also in warehouses, storage rooms, break rooms, etc.

So it is not required by the NEC directly to consider lighting continuous, though it happens to almost always be continuous.

If this flower shop will be open for business to make a profit, I would expect it to be "continuous".

The problem is that the NEC does not tell us in Article 220 to calculate it that way, Art. 220 does not refer to Art. 210, and I know of no rule in Article 240 that would do it either.

 

[cadpoint]

...

The problem is that the NEC does not tell us in Article 220 to calculate it that way, Art. 220 does not refer to Art. 210, and I know of no rule in Article 240 that would do it either.

-
Food for the Host!!!

 

[wawireguy]

You can't just omit a AC load because it won't be used much. And where is the heat load or is that the HVAC? This thing is a moving target.

 

[wawireguy]

Here's my load calc:

General lighting: 2411 x 3VA = 7233 x 1.25 = 9041
2 AC units = 18000
Omit heat(this is Texas)
Condenser = 1608
Chiller = 4800
Receptacles 180VA x 8 = 1440
Omit signage per OP, feeds from other service
Largest motor(assume AC) .25 x 9600 = 2400
Track lighting = 1875

Grand total = 39164/240 = 163 amps

It's probably fudging to omit the signage but since another service covers the sign I decided to not include it. I saw where the OP added signs later but I'm basing this off the first set of numbers. If this were my job I'd verify the AC, chiller and condenser loads with the manufactures. I dont' know about Texas but in WA for 2500 square foot that is a lot of AC capability.