USE OF TABLE 220.44 FOR FEEDER CALCULATIONS IN OFFICES AND BANKS - NEC 2014

[eallen]

San Jose has started enforcing a code interpretation that states for offices and banks we cannot use Table 220.44 diversity factors for receptacle loads when sizing feeders, panels or equipment, even if we use 220.14 (H or I) as the larger number to 220.14(K)1 or 2 for offices or bank receptacle branch loads.

The City Inspection stated that they just had a training a few weeks ago and this was brought up during their training session.

We tried to go to NFPA and pose the technical question to see if this is correct, hoping we can get the interpretation as we know it, but a NFPA technical specialist also stated that we cannot use 220.44 diversity of receptacles for offices and banks.
Not sure if NFPA is providing this training.

Both NFPA specialist and City of San Jose are stating that we must calculate office or bank loads at 100% to calculate feeder and equipment sizes.

We are wondering if anyone else in the industry has encountered this issue.

 

[petersonra]

San Jose has started enforcing a code interpretation that states for offices and banks we cannot use Table 220.44 diversity factors for receptacle loads when sizing feeders, panels or equipment, even if we use 220.14 (H or I) as the larger number to 220.14(K)1 or 2 for offices or bank receptacle branch loads.

The City Inspection stated that they just had a training a few weeks ago and this was brought up during their training session.

We tried to go to NFPA and pose the technical question to see if this is correct, hoping we can get the interpretation as we know it, but a NFPA technical specialist also stated that we cannot use 220.44 diversity of receptacles for offices and banks.
Not sure if NFPA is providing this training.

Both NFPA specialist and City of San Jose are stating that we must calculate office or bank loads at 100% to calculate feeder and equipment sizes.

We are wondering if anyone else in the industry has encountered this issue.

Well the code actually does say this, so I think they are right, at least as far as not using table 220.44.

220.14
(K) Banks and Office Buildings. In banks or office buildings,
the receptacle loads shall be calculated to be the larger
of (1) or (2):
(1) The calculated load from 220.14(1)
(2) 11 volt-amperes/m2 or 1 volt-ampere/ft2

 

[eallen]

USE OF TABLE 220.44 FOR FEEDER CALCULATIONS IN OFFICES AND BANKS - NEC 2014

Thank You,

We agree with that Section - Part II - Branch Circuit load Calculations. The larger of the (2)loads in 220.(K) 1 or 2 must be utilized for offices and banks.

What we are questioning, is once you are forced to use 220.14(H or I) as being the larger of the two numbers, why can we NOT use Table 220.44 for the Part III - Feeder and Service Load Calculations. This section states that 220.14 (H) and (I) loads can be diversified using Table 220.44. Then recheck if 220.14 (K).2 is still the smaller number after diversifying 220.14(K).1.

The example below came from a thread in an EC&M article:

"It's common not to know the exact number of receptacles that will eventually be installed in an office building or bank. The main structure is built first, then individual office space that's rented out to each tenant will often have a custom installation — or a new tenant will remodel the space to fit his or her needs. A calculation of 1VA per square foot allows a generic feeder/service demand for general receptacles.

What is the receptacle calculated load for an 18,000-sq-ft bank/office building containing 160 15A and 20A, 125V receptacles (straps)? [220.14(K)(1)], as shown in Fig. 3.
160 receptacles (straps) x 180VA [220.14(I)] = 28,800VA

Total receptacle load = 28,800VA
First 10,000VA at 100% (10,000VA x 1.00 = 10,000VA)
Remainder at 50% (18,800VA x 0.50 = 9,400VA) [Table 220.44]

Receptacle calculated load = 19,400VA

Compare this to the 1VA per sq ft method [220.14(K)(2)]

18,000 x 1VA per sq ft = 18,000VA (smaller answer, omit)"

 

[petersonra]

How about you can't use the table becasue the loads did not come from the two sections it says you can use it for.

 

[jumper]

I think the ECM article is correct. 220.14(K)(1) sends you to 220.14(I) and then you can use the demand factors given in T220.44.

Note: these are demand factors, your "diversify" is not NEC and should be avoided IMO.

 

[steve66]

220.12 K and L are pretty clear.

Loads from table 220.12 can have the demand factors from table 220.42 applied, but unfortunately, banks aren't listed in 220.42, so the demand factor would be 100% as listed under "All others."

Demand factors in 220.44 only apply when you are adding up the VA's from each receptacle or outlet.

1 W/SF doesn't seem like a lot for a bank anyway. Its the 3.5 W/SF that I always question. But I usually just accept that too, because I often think the extra may be needed for receptacle loads since banks seem to have a lot of computers and such.

 

[eallen]

220.44 FOR BANKS AND OFFICES

220.44 FOR BANKS AND OFFICES

Thank you all for your responses, I appreciate the information. Just as a note, The city has decided to back away and not enforce the interpretation from their recent training and allow 220.44 to be utilized if method of calculation comes from 220.14(H and I) .