A question for existing residential load calc.

[fandi]

Hi All,
Since there are no quantified demand factors mentioned in the dedicated sections of AC units (article 440) and EV chargers (article 625), can I use the demand factor in section 220.83 (A) for AC and EV charger?
These items seems to meet the description of 220.83(A)((3)(a): 'All appliances that are fastened in place, permanently connected, or located to be on a specific circuit'.
Thanks.

 

[Dennis Alwon]

I think you have to use 220.83(B) since you are adding a/c

 

[fandi]

Thanks Mod. That means the new A/C is at 100%. What if the A/C is existing? I guess 220.83(A) is to be used. That case, can I use a demand factor for the existing A/C ?
For the EV charger, can I use the demand factor, either 220.83(A)((3)(a) or '220.83(B)((3)(a) ?
'All appliances that are fastened in place, permanently connected, or located to be on a specific circuit'.

 

[jaggedben]

Yes, you can, although I've run into a couple AHJs who made up their own rule against it.

 

[fandi]

Yes, you can, although I've run into a couple AHJs who made up their own rule against it.

I heard that you can't use demand factors for A/C units (existing or new) and EV chargers?

 

[jaggedben]

I heard that you can't use demand factors for A/C units (existing or new) and EV chargers?

I don't know what you 'heard' but article 220 has yet to see any rule specific to EV chargers. So you can lump them in with the general appliance load and use any applicable demand factor. (It's probably only a matter of time before that changes but for now it holds true.) In my previous post I meant only to refer to EV chargers. A/C is treated a little differently as mentioned above.

 

[fandi]

I don't know what you 'heard' but article 220 has yet to see any rule specific to EV chargers. So you can lump them in with the general appliance load and use any applicable demand factor. (It's probably only a matter of time before that changes but for now it holds true.) In my previous post I meant only to refer to EV chargers. A/C is treated a little differently as mentioned above.

For A/C, it seems that it depends on whether the A/C is new or existing. If it's new, 220.83(B) to be used and therefore 100% (no demand factor).
If it's existing, 220.83(A) to be used and therefore a demand factor can be used.

 

[fandi]

I don't know what you 'heard' but article 220 has yet to see any rule specific to EV chargers. So you can lump them in with the general appliance load and use any applicable demand factor. (It's probably only a matter of time before that changes but for now it holds true.) In my previous post I meant only to refer to EV chargers. A/C is treated a little differently as mentioned above.

EV chargers are continuous loads per 625.42. Can a demand factor be used for continuous loads?

 

[cyriousn]

EV chargers are continuous loads per 625.42. Can a demand factor be used for continuous loads?

Yes the load being continuous doesn't matter. Lighting and an appliance like an oven could be considered a continuous loads and those fall under the "other" category that are subject to the 40 percent demand factor. What is the size of the existing electrical service and what is the size that the calc is working out to? I used to do a lot of residential calculations ranging from small NYC apartments to large estate services. One thing we would always do is take the full connected load and compare it to the the service size that the calc. comes up with to sanity check that there wasn't too much or not enough diversity taken especially if you are dealing with someone with a 100A service. Every home owner is different and they might have expectations. Future loads should may also need to be taken into account. Might be worth talking with the owner quickly to not get yourself in a jam.

 

[fandi]

Yes the load being continuous doesn't matter. Lighting and an appliance like an oven could be considered a continuous loads and those fall under the "other" category that are subject to the 40 percent demand factor. What is the size of the existing electrical service and what is the size that the calc is working out to? I used to do a lot of residential calculations ranging from small NYC apartments to large estate services. One thing we would always do is take the full connected load and compare it to the the service size that the calc. comes up with to sanity check that there wasn't too much or not enough diversity taken especially if you are dealing with someone with a 100A service. Every home owner is different and they might have expectations. Future loads should may also need to be taken into account. Might be worth talking with the owner quickly to not get yourself in a jam.

If the demand factor is used for the A/C and the EV charger, the total load is about 91A. The service size is 100A. The owner said he doesn't think new loads will be added after this project. And he doesn't plan to upgrade the service either.
I just don't know why NEC has a dedicated section 625 for EV chargers and no demand factor mentioned in that section.
As for the A/C, now I'm not even sure if the existing A/C can be lumped to the general loads after reading 220.14(A)
as I don’t see A/C is listed in 220.14(B) through (L).

Section 220.14 (A) states that

(A) Specific Appliances or Loads. An outlet for a specific

appliance or other load not covered in 220.14(B) through (L)

shall be calculated based on the ampere rating of the appliance

or load served.

 

[cyriousn]

If the demand factor is used for the A/C and the EV charger, the total load is about 91A. The service size is 100A. The owner said he doesn't think new loads will be added after this project. And he doesn't plan to upgrade the service either.
I just don't know why NEC has a dedicated section 625 for EV chargers and no demand factor mentioned in that section.
As for the A/C, now I'm not even sure if the existing A/C can be lumped to the general loads after reading 220.14(A)
as I don’t see A/C is listed in 220.14(B) through (L).

Section 220.14 (A) states that

(A) Specific Appliances or Loads. An outlet for a specific

appliance or other load not covered in 220.14(B) through (L)

shall be calculated based on the ampere rating of the appliance

or load served.

The Air Conditioning falls under 220.83(A)(3) - appliances. Article 100 definition of appliance includes Air Conditioning. Also heating and cooling loads don't both need to be included, only higher of the two based on 220.60. 220.14 just says that the load must be derived by the nameplate of that device since it doesn't fit into (B) through (L)

 

[jaggedben]

... I just don't know why NEC has a dedicated section 625 for EV chargers and no demand factor mentioned in that section.
...

I thought you were asking what the code says. If you are asking what it should say, that's a different question. Same if you are asking what is prudent advice to give a customer.

Also so far as I've noticed most demand factors are in article 220 not in the article that deals with specific equipment. Although there are EV charging systems that manage total demand for multiple chargers and the code probably needs to acknowledge that in 625 as well as 220.

 

[fandi]

I thought you were asking what the code says. If you are asking what it should say, that's a different question. Same if you are asking what is prudent advice to give a customer.

Also so far as I've noticed most demand factors are in article 220 not in the article that deals with specific equipment. Although there are EV charging systems that manage total demand for multiple chargers and the code probably needs to acknowledge that in 625 as well as 220.

I asked for what the code says.

 

[fandi]

The Air Conditioning falls under 220.83(A)(3) - appliances. Article 100 definition of appliance includes Air Conditioning. Also heating and cooling loads don't both need to be included, only higher of the two based on 220.60. 220.14 just says that the load must be derived by the nameplate of that device since it doesn't fit into (B) through (L)

220.14 Other Loads — All Occupancies. In all occupancies,
the minimum load for each outlet for general-use receptacles
and outlets not used for general illumination shall not be less
than that calculated in 220.14(A) through (L), the loads shown
being based on nominal branch-circuit voltages.

 

[cyriousn]

220.14 Other Loads — All Occupancies. In all occupancies,
the minimum load for each outlet for general-use receptacles
and outlets not used for general illumination shall not be less
than that calculated in 220.14(A) through (L), the loads shown
being based on nominal branch-circuit voltages.

look at 220.14 (A), are we in agreement that the AC falls under (A)? not sure what you mean by this post other than I forgot to put (A) at the end of my previous post.

 

[fandi]

look at 220.14 (A), are we in agreement that the AC falls under (A)? not sure what you mean by this post other than I forgot to put (A) at the end of my previous post.

220.14 (A) asks to read from 220.14 (B) through (L) but A/C is not listed under 220.14 (B) through (L).

 

[cyriousn]

220.14 (A) asks to read from 220.14 (B) through (L) but A/C is not listed under 220.14 (B) through (L).

A is for anything not in B through L. A/C is not in B through L so it's covered under A.

 

[jaggedben]

Just pointing out that the original question was about 220.83, and I don't believe 220.14 matters at all when it comes to calculations made under the optional 220.8x sections.

 

[cyriousn]

Just pointing out that the original question was about 220.83, and I don't believe 220.14 matters at all when it comes to calculations made under the optional 220.8x sections.

Agreed. I think we got into a tail spin in a search to determine what type of load A/C is. The calculations of 220.83(A) and 220.83(B) do not use the diversities listed in 220.14 (B) through (L).

 

[fandi]

Just pointing out that the original question was about 220.83, and I don't believe 220.14 matters at all when it comes to calculations made under the optional 220.8x sections.

Sorry to disagree. The section to be used should be 220.16(A)(2) which refers back to 220.12 or 220.14 as applicable.