220.44 – Handbook Commentary

[Smart $]

I read it again, and I agree. Table 220.42 applies to the general lighting load, regardless if its calculated from the connected load, or the table 220.12. That makes more sense.

So how does one calculate the guest room receptacle load when you are using the total connected lighting load? If we were using table 220.12, we wouldn't have to count them at all per 220.12 (J).

But we are using the total connected lighting load, not table 220.12. It seems like we should have to add something for the guest room receptacles. I

t sounds like Charlie is using 180VA per duplex, and in that case it seems like he can definitely use the demand factors in table 220.42.

You are required to use section 220.12. All that is required is the volt-ampere per square foot value be equal or greater than the value required by Table 220.12.

The rest falls in place per NEC design.

 

[steve66]

You are required to use section 220.12. All that is required is the volt-ampere per square foot value be equal or greater than the value required by Table 220.12.

The rest falls in place per NEC design.

I disagree if the connected lighting load exceeds the load listed in table 220.12.

Table 220.12 says it is the minimum lighting load required. Nothing in 220.12 gives permission to ignore the calculations in 220.14, if that produces a higher calculated load. The handbook commentary I posted above seems to confirm that.

 

[Smart $]

I disagree if the connected lighting load exceeds the load listed in table 220.12.

Table 220.12 says it is the minimum lighting load required. Nothing in 220.12 gives permission to ignore the calculations in 220.14, if that produces a higher calculated load. The handbook commentary I posted above seems to confirm that.

Let's use an easy example.

Charlie's hotel general lighting load is required to be not less than 2VA/ft² for 200,000 ft², or 400kVA. He's calculated his connected lighting load as 585kVA... which is equivalent to 585kVA ÷ 200,000 ft² = 2.925VA/ft². Section 200.12, including Table 220.12, is being complied with if he uses 585kVA or 2.925VA/ft².

The general receptacle load under 220.14(J) is included in the 585kVA general lighting load calculated per 200.12.

The demand factors of 220.42 can be applied to 585kVA... and the result would cover general lighting and receptacle load.

 

[Strathead]

I disagree if the connected lighting load exceeds the load listed in table 220.12.

Table 220.12 says it is the minimum lighting load required. Nothing in 220.12 gives permission to ignore the calculations in 220.14, if that produces a higher calculated load. The handbook commentary I posted above seems to confirm that.

As you or someone else pointed out, the handbook isn't code. I would contend that if the code writers had wanted to make that code they would have stated it especially in lieu of a footnote warning that the load may not be adequate. I was recently slapped down here when trying to contend that there had to be some restriction on the number of duplexes you can put on a residential circuit. I was convinced that I was wrong. It is the same code that we are discussing here. I also contend that if the authors had wanted to read it the way you do, they would required you to do the connected lighting load calculations and compare it to the table. Lastly and most importantly, is the service going to be incapable of handling the worst case scenario at the hotel in question. I would assume the OP wasn't concerned about this, or he wouldn't have started this thread.

 

[Smart $]

Let's use an easy example.

Charlie's hotel general lighting load is required to be not less than 2VA/ft² for 200,000 ft², or 400kVA. He's calculated his connected lighting load as 585kVA... which is equivalent to 585kVA ÷ 200,000 ft² = 2.925VA/ft². Section 200.12 [220.12], including Table 220.12, is being complied with if he uses 585kVA or 2.925VA/ft².

The general receptacle load under 220.14(J) is included in the 585kVA general lighting load calculated per 200.12 [220.12].

The demand factors of 220.42 can be applied to 585kVA... and the result would cover general lighting and receptacle load.

Corrections in red.

 

[steve66]

Let's use an easy example.

Charlie's hotel general lighting load is required to be not less than 2VA/ft² for 200,000 ft², or 400kVA. He's calculated his connected lighting load as 585kVA... which is equivalent to 585kVA ÷ 200,000 ft² = 2.925VA/ft². Section 200.12, including Table 220.12, is being complied with if he uses 585kVA or 2.925VA/ft².

The general receptacle load under 220.14(J) is included in the 585kVA general lighting load calculated per 200.12.

The demand factors of 220.42 can be applied to 585kVA... and the result would cover general lighting and receptacle load.

I mostly agree with that. I thought you were saying you could use the smaller 400KVA and the demand factors in table 220.42.

 

[Strathead]

I mostly agree with that. I thought you were saying you could use the smaller 400KVA and the demand factors in table 220.42.

The code is an inclusive document. There is nothing that says you are required to calculate the load of general lighting in any other way. It tells you the minimum will be 2va per foot. That just means it can't be less.
If there really was an issue that the entire building load as calculate exceeded the the conductor size then you would need to upsize them for that purpose, but let's be realistic here, that isn't going to happen.

 

[steve66]

As you or someone else pointed out, the handbook isn't code. I would contend that if the code writers had wanted to make that code they would have stated it especially in lieu of a footnote warning that the load may not be adequate. I was recently slapped down here when trying to contend that there had to be some restriction on the number of duplexes you can put on a residential circuit. I was convinced that I was wrong. It is the same code that we are discussing here. I also contend that if the authors had wanted to read it the way you do, they would required you to do the connected lighting load calculations and compare it to the table. Lastly and most importantly, is the service going to be incapable of handling the worst case scenario at the hotel in question. I would assume the OP wasn't concerned about this, or he wouldn't have started this thread.

I was just about to say it is in the code in 220.14(D), right where the handbook commentary is.

But I just noticed the title of 220.14 is "Other loads - All Occupancies", and the text of the first paragraph of 220.14 specifically excludes general lighting load.

That leaves me on the fence - the code seems to say one thing while the handbook commentary says something different.

I tend to think you are correct and per code, you can use table 220.12 and ignore 220.14 for general lighting loads. In Smart$'s example, that means we could use the 400KVA and apply the demand factors to it.

At any rate, one could still be a little more conservative and use the total connected lighting load when it exceeds the load listed in 220.12. It gives a little more safety buffer, and it doesn't leave any doubt you are meeting code.

 

[Strathead]

I was just about to say it is in the code in 220.14(D), right where the handbook commentary is.

But I just noticed the title of 220.14 is "Other loads - All Occupancies", and the text of the first paragraph of 220.14 specifically excludes general lighting load.

That leaves me on the fence - the code seems to say one thing while the handbook commentary says something different.

I tend to think you are correct and per code, you can use table 220.12 and ignore 220.14 for general lighting loads. In Smart$'s example, that means we could use the 400KVA and apply the demand factors to it.

At any rate, one could still be a little more conservative and use the total connected lighting load when it exceeds the load listed in 220.12. It gives a little more safety buffer, and it doesn't leave any doubt you are meeting code.

I agree, but this all started because Bill doesn't want to increase the size of the service, or have to split it.

 

[Smart $]

I mostly agree with that. I thought you were saying you could use the smaller 400KVA and the demand factors in table 220.42.

Technically, you can. Code doesn't actually say you must use connected load if greater than the table. It just says you cannot use less.

...And I see you came to that conclusion also...

...
I tend to think you are correct and per code, you can use table 220.12 and ignore 220.14 for general lighting loads. In Smart$'s example, that means we could use the 400KVA and apply the demand factors to it...

 

[jumper]

I agree, but this all started because Bill doesn't want to increase the size of the service, or have to split it.

Bill?:?

This is charlie b's thread and he never mentioned anything about "splitting a service", whatever that means.

 

[Strathead]

Bill?:?

This is charlie b's thread and he never mentioned anything about "splitting a service", whatever that means.

Sorry, I was thinking Bill started it. That's what I get for being lazy and not looking back. He was talking large sizes. 5000 amps and 6000 amps. He didn't mention splitting, but the utility companies in my area, don't have 120/208 transformers that are that big. I think the largest is something around 2800 amps. That would mean splitting the service. that was what I meant.

 

[jumper]

Sorry, I was thinking Bill started it. That's what I get for being lazy and not looking back. He was talking large sizes. 5000 amps and 6000 amps. He didn't mention splitting, but the utility companies in my area, don't have 120/208 transformers that are that big. I think the largest is something around 2800 amps. That would mean splitting the service. that was what I meant.

Gotcha.

 

[Strathead]

Gotcha.

Well there is a B in his name.