Nec-2008 220.87(2)

[Team-MEI]

For existing facility feeder(s) or service(s); include the effect of deleted load in total "new load" calculations or not?

Current review process has revealed a rather surprising grey area (it is not a grey area to me) within NEC-2008 220.87.(2) in which an NFPA interpretation needs to occur; this forums' several informed opinions will do nicely though. The reviewer does not allow deleted loads from being included in determining the final or total ?new load? calculations. The current review position seems incorrect to me. The particular code section mentioned does not specify or precisely limit the term ?new load? nor is the term ?load? defined in section 100. However, section 220.60 ?total load? seems to unintentionally but directly apply to this situation. It should be noted in this instance, that not only were certan utilization equipments deleted, but the deleted loads in question also had its entire wiring and associated electrical devices removed per plans.

Do you agree or not? For the purposes of calculating ?new load? according to NEC-2008 220.87.(2); the new load shall be considered to include the combined loads per designated load type being present; consisting of (1) existing peak demand based upon most recent historical meter recordings multiplied by 125% (including those loads which will be deleted) plus any applicable seasonal or periodic adjustment factors if 30-day meter-recording method was used; (2) less any loads being deleted within appropriate demand load type; (3) plus any loads being added within appropriate demand load type.

 

[barbeer]

I'm cornfused! I think you are asking if it is o.k. to delete existing loads to be removed from a load calculation? If I get plans for a project.....I expect to see an existing load calc. and a proposed load calc with the changes made.

 

[Team-MEI]

Yes, that?s essentially what I am asking; we have ?before? or existing load calculations and we have ?after? or final new load calculations; for the final load calculations is it OK to take into account the deleted loads by not including those loads within the final new load calculation? The state is saying we must still include those loads in the final load tabulation even if those loads were deleted.

 

[Smart $]

...consisting of (1) existing peak demand based upon most recent historical meter recordings multiplied by 125% (including those loads which will be deleted) plus any applicable seasonal or periodic adjustment factors if 30-day meter-recording method was used; (2) less any loads being deleted within appropriate demand load type; (3) plus any loads being added within appropriate demand load type.

If the "30-day record" includes existing loads to be removed (TBR), you can't simply subtract the TBR loads from the recorded data, as there is no way to know when all, some, or none of the TBR loads are using power.

The only way to get an accurate 30-day recording is to remove the TBR loads from service, then take the recording. Otherwise, there is no way for the review officials to know how removal of these loads will affect existing load demand.

Since you have resorted to a 30-day recording, I'm assuming 1 year of demand data is not available... so the only other method is a comprehensive load calculation.

 

[Team-MEI]

Didn?t remove existing loads from recorded loads; would like to do it later while calculating ?new load?. In addition to accounting for existing loads at 150%, for replacing lights & HVAC; remove the nameplate loads for those being deleted and add same for those added.

The existing loads measured by meter readings are already accounted for at 125% plus another 25% for seasonal adjustments; from that point, only account for loads per load type at proscribed NEC demand rates, whether added or deleting, so we already have a rather large built-in safety margin.

Besides, having to explain to a client that the situation of the projects? new loads are much more efficient and use less energy but we have to increase the size of the feeders and gear because we cannot properly take into account deleted loads that are no-longer present for final load tabulation purposes!? This would be a very difficult discussion.

?New load? per NEC-2008 220.87(2) can only mean ?for loads present?; but I would like to hear from others.

 

[Smart $]

Didn’t remove...

I understand what you are attempting to do, and cannot say the result is in error.

Yet the NEC has no provision for adjusting a 30-day demand data recording, or documented 1-year demand data from POCO for that matter, to compensate for existing-TBR loads.

Your only NEC option is to do a comprehensive load calculation any way you look at it.

 

[Team-MEI]

??the NEC has no provision for adjusting a 30-day demand data recording??

Did not adjust the 30-day demand; it is just that on Step2; the ?plus the new load? portion, I am saying the ?new load? properly consists of, and should account for, the deleted loads being subtracted and the new being added; and that amount is then combined with the 30-demand loads.

(Step1) [The maximum demand at 125 percent] plus (Step2) [the new load] does not exceed the ampacity of the feeder or rating of the service.

When I ask myself what the ?new load? is; I see what is connected but I do not see what used to be connected; pure nonsense to do it any other way. The code does not say the ?new load? is only made up from any added loads. The code does not say the ?new load? shall include any deleted loads plus any added loads. The code says:

??maximum demand at 125 percent plus the new load??

and the ?new load?, in my opinion, does not (and cannot be forced to) include loads which are no longer present.

Besides, if one was nutty enough to include these deleted loads as part of the ?new load?, then other NEC sections like I mentioned earlier, 220.60 would disallow any deleted loads becoming or counting as part of ?new load?;

220.60 Noncoincident Loads. Where it is unlikely that two or more noncoincident loads will be in use simultaneously, it shall be permissible to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service.

Because I am really sure deleted loads will never be on at the same time as other loads and I am also pretty sure deleted loads will always be the smaller load by comparison.

 

[Smart $]

Did not adjust the 30-day demand...

That is a matter of opinion... and from the sounds of it, the plan reviewer for your project has a different opinion than yours also.

To say the "new load" is equal to existing to be removed and added loads is, IMO, quite a stretch on the meaning and/or intent.

 

[Team-MEI]

I want to share with you a formal interpretation I received from the NEC pertaining to this question; Does NEC-2008 220.87 "new load" contain deleted loads?



RE: NEC-2008 220.87 question (Log #NNNNN)CC

This is in reply to your request for a formal interpretation and email concerning the National Electrical Code? (NEC?).



REPLY: ?Section 220.87 does not require deleted loads to be included in the calculation of the new load.?