what demand % do I use?

[Grouch1980]

Hey all,
I have a hotel that i am working on. Each guest room has a refrigerator and a coffee maker, for a total of 20 rooms. What demand factor does the NEC allow me to take on all the refrigerators and coffee makers? the only section that I could find that would fit this is section 220.56 (NEC 2008). Since I have more than 6 'units of equipment' (as per the table), I would take a 65% demand factor. But is this the right section to be using? Section 220.56 is titled "Kitchen equipment - Other than Dwelling Units".

Thanks again!

 

[ActionDave]

I don't think a motel room qualifies as a commercial kitchen. I would use 220.44.

 

[Glock23gp]

Refrigerator and coffee maker are cord connected and not considered "commercial cooking equipment"

I don't have 2008 handy but check 220.14 J. It explains how to calculate the receptacle load in a hotel.

Basically tells you T220.12 at 2 va / sq ft then use T220.42 for final derating

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[Smart $]

I'm with the others. Use 220.44.

 

[Grouch1980]

So based on 220.44, it sends me to 220.14(H) and (I)... (H) can be disregarded since it's for places other than guest rooms of hotels, so I look at (I). (I) sends me to 220.14(J). According to 220.14(J), these refrigerator and coffee maker outlets can be considered general use receptacles?

 

[ActionDave]

So based on 220.44, it sends me to 220.14(H) and (I)... (H) can be disregarded since it's for places other than guest rooms of hotels, so I look at (I). (I) sends me to 220.14(J). According to 220.14(J), these refrigerator and coffee maker outlets can be considered general use receptacles?

That is correct.

 

[Grouch1980]

Interesting. So 220.14(J) refers me to table 220.12, where I would use 2 VA/sqft, and then I would apply the derating factors in table 220.42 as Glock mentioned.

I think this is where i'm confusing what a general use receptacle is. If you have a refrigerator, microwave, coffee maker, or any similar appliance connected to a receptacle, and the appliance may be rated 1000 - 1500 VA (or watts)... these are still general use receptacles? and hence I can apply section 220.14(J) for the refrigerators and coffee makers in a hotel room?

 

[Strathead]

One question for the gurus... Why wouldn't a refrigerator be a specific appliance, per 220.14 (A) and require its load to be accounted for? And why wouldn't a coffee pot and say a microwave be "cooking appliances" and be covered under 220.14(B)?

 

[Smart $]

So based on 220.44, it sends me to 220.14(H) and (I)... (H) can be disregarded since it's for places other than guest rooms of hotels, so I look at (I). (I) sends me to 220.14(J). According to 220.14(J), these refrigerator and coffee maker outlets can be considered general use receptacles?

...
I think this is where i'm confusing what a general use receptacle is. ...

220.14(I) says "Except as covered in 220.14(J)..." so it is your choice whether these outlets are covered in (I) or (J). And as Strathead brings up, the refrigerator (or anything for that matter, including the coffee maker) can be calculated under 220.14(A). 220.14(I) can be used in the same manner as (A) simply because a receptacle is involved (you just can't go below 180VA per yoke or 90VA per 4-plug device).

 

[petersonra]

It appears to me you can pretty much do what you want as far as how this is calculated.

keep in mind that coffee pots and small refrigerators typical are very low duty cycle loads. most coffee pots found in a typical hotel room will run for no more than 30 seconds a day, if that.

 

[Grouch1980]

220.14(I) says "Except as covered in 220.14(J)..." so it is your choice whether these outlets are covered in (I) or (J). And as Strathead brings up, the refrigerator (or anything for that matter, including the coffee maker) can be calculated under 220.14(A). 220.14(I) can be used in the same manner as (A) simply because a receptacle is involved (you just can't go below 180VA per yoke or 90VA per 4-plug device).

So, it seems like I can follow one of three methods:
1) Follow 220.14(I) and use the nameplate rating of the refrigerator and coffee maker for the receptacle they plug into. Can I then apply the demand factors of Table 220.44?

2) Follow 220.14(J) and include the refrigerator and coffee maker as part of the general use receptacles and then apply 2 VA/sqft. and then apply the demand factors of Table 220.42.

3) Follow 210.14(A) and use the nameplate rating of the refrigerator and coffee maker. But what demand factors can I apply?

Seems kind of strange you're allowed to choose a method. If 2 engineers go with 2 different methods, they will get different amperage values as their final results, and that will affect the size of the main circuit breaker / fuses. Wouldn't one main circuit breaker / fuse be in more danger of tripping / melting than the other?

 

[Smart $]

1) Yes.

2) You really wouldn't do anything for these [small] appliances. They are simply "absorbed" by the general lighting load calculation, to which 220.42 applies.

3) No demand factor applies.

Using 2 different methods may affect the main size. You could use 220.14(J) which will yield the lowest calculation result, and chances are a coffee maker or refrigerator load will never cause a main trip. If one ever does, you have more and bigger problems than that one appliance. Demand calculations are quite conservative compared to most real, in-use demand peaks.

 

[JFletcher]

Fridges and coffee pots are low draw compared to microwaves, irons, and hairdryers, the last of which can be wall-mounted units; any of those present?

 

[Grouch1980]

Fridges and coffee pots are low draw compared to microwaves, irons, and hairdryers, the last of which can be wall-mounted units; any of those present?

No microwaves, no irons. We do have hairdryers, but my understanding is that hairdryers for hotel guest rooms are covered under 220.14(J)(1), which sends you to 210.11(C)(3)... and so the hairdryers can be absorbed by the General lighting load calculations of Table 220.12.

 

[Grouch1980]

Refrigerator and coffee maker are cord connected and not considered "commercial cooking equipment"

I don't have 2008 handy but check 220.14 J. It explains how to calculate the receptacle load in a hotel.

Basically tells you T220.12 at 2 va / sq ft then use T220.42 for final derating

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What exactly defines a receptacle as a general use receptacle? If the cord connected load is non-continuous? What about ampere rating?... does it have to be 20 amps or less?

 

[Glock23gp]

What exactly defines a receptacle as a general use receptacle? If the cord connected load is non-continuous? What about ampere rating?... does it have to be 20 amps or less?

If it's not specifically defined as something you need to calculate for per ART. 220 ( sq ft, range, dryer, known equip at nameplate value, dryer, AFIP at nameplate value (disp, IH, DW, exhaust fans..., motors etc...) then it's just 180 va per outlet.

You can use T220.42 for lighting and receptacles if the voltage is the same for both. (Art 220.44 not the table tells you this)

As you can see that table gives you a way better derate than T220.44.

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[Grouch1980]

If it's not specifically defined as something you need to calculate for per ART. 220 ( sq ft, range, dryer, known equip at nameplate value, dryer, AFIP at nameplate value (disp, IH, DW, exhaust fans..., motors etc...) then it's just 180 va per outlet.

You can use T220.42 for lighting and receptacles if the voltage is the same for both. (Art 220.44 not the table tells you this)

As you can see that table gives you a way better derate than T220.44.

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So if the receptacle is only 180 va, then it's considered a general use receptacle?

 

[Glock23gp]

No. if your given a specific number of receptacles to calculate you use 180 va per and the final derated value can be no less than the 2 va / sq ft as shown in table.

You sound like your trying to calculate each room so you would use the 2 va / sq ft for your lighting and general purp plugs and ignore the 180 va per recep. Then add ranges, dryers, afip, heat etc

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[Grouch1980]

No. if your given a specific number of receptacles to calculate you use 180 va per and the final derated value can be no less than the 2 va / sq ft as shown in table.

You sound like your trying to calculate each room so you would use the 2 va / sq ft for your lighting and general purp plugs and ignore the 180 va per recep. Then add ranges, dryers, afip, heat etc

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Oh no, that part I know, I'm using 2 va/sqft. It's just a general question... What defines a general use receptacle?

 

[Smart $]

... What defines a general use receptacle?

Technically, any receptacle that is not for a specific purpose. And though some may seem to have a specific purpose, they are still general-purpose receptacles because the utilization equipment that seems to make them specific purpose can be readily plugged in somewhere else.