Hotel Hairdryer, etc., Panels

[rwilsond]

For a large existing hotel two new circuits will be added to each guest room to eliminate nuisance CB trips caused by too many coffee pots and hairdryers. These new circuits will feed only one receptacle each per room (one for a hairdryer & one for a coffee pot). New panels & transformers will be added to accommodate only these new circuits. Of course, overall, only a fraction of the coffee pots & hairdryers would operate simultaneously, at any given time (short of a vast conspiracy conducted by the quests). Using connected load data to size distribution equipment and feeders results in oversizing, simply to suit the NEC. Is there anything such as a demand factor that could be applied to the panel, transformer, and feeder sizes that would be code-compliant?

 

[bphgravity]

Re: Hotel Hairdryer, etc., Panels

Perhaps you could use 220.13 of the NEC to figure the receptacle loads. Figure each room at 360 VA, times that by the number of rooms, and then apply the demand factor in Table 220.13. You will not see a benefit unless you have well over 30 rooms.

 

[charlie b]

Re: Hotel Hairdryer, etc., Panels

That is as good approach as you are going to find. But it is giving you more of a demand factor than the table would appear to be giving you. A 1200 watt hair dryer runs around 10 amps. You are assigning a load of only 1.5 amps (180 VA) to that hair dryer. Coffee pots also draw well over 1.5 amps each. Since you are not adding the actual connected load, but rather are assigning a load that is perhaps 15% of the actual connected load, you are getting smaller panels and transformers.

 

[rwilsond]

Re: Hotel Hairdryer, etc., Panels

Thanks for the input guys. Someone else suggested I use "Engineering Judgment". But I'm not aware of any NEC reference or allowance for "Engineering Judgment". Since we have about a thousand of each type of load, I think an argument could be constructed for using demand factors for wiring and equipment above the branch circuit level, which serves the specific loads of hairdryers & coffee makers.

The justification could include references to somewhat similar situations where demand factors are allowed for appliances such as for electric clothes dryers in dwelling units (such as apartment buildings), as in Table 220.18 of the 1999 NEC. For example, this table allows a demand factor of 0.25 for "43 and over" electric clothes dryers. Unfortunately, this particular hotel does not fall under the NEC's definition of a "dwelling unit"; but this is only because of the absence of cooking facilities.

Section 220.21 ("Noncoincident Loads") of the 1999 NEC may also provide some support for using demand factors (such as those of Table 220.18), although I think it is more of a stretch.

As for the branch circuits, I believe they should be sized at 100% of the connected loads that were provided to us by the owner.

Any comments?

 

[LarryFine]

Re: Hotel Hairdryer, etc., Panels

I'd broach the subject with the AHJ.

 

[mdshunk]

Re: Hotel Hairdryer, etc., Panels

I'm picturing doing a service call in this facility and seeing marking on stuff that says "Hairdryer panel", "hairdryer transformer", "coffeepot and hairdryer panels MDP". That would make some funny internet pics. 1,000 rooms! Holy cow, big hotel.