Who's Responsible?

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360Youth

360Youth

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Newport, NC
NC is now under 2008 NEC as of June 1st and I am having to remind myself of that when we pull permits :rolleyes: :) . One of the code changes is, of course, sizing generators per ART 220 calculations. I have had conversations with our salesman to keep that in mind, but who does that fall back on should it arise within any inspections. Most inspectors I would think are not going to push it that much, but I know of a few that will probably ask. They are just that way. If a salesman makes the sale, or the HO buys and hires an EC for the install, who will be held liable for whether or not the generator is sized properly? In our case I think it would still fall back on our license bescause there is no separation of sales division and electrical division, but it has caused me to ponder....Things that make you go...hmmmm? :)
 
If you are asking whether you are responsible for sizing of the generator I would say yes. If you pulled the permit and hook up the generator then you would need to make sure the gen can handle the load.
 
WA is not yet under the 2008, nor is any of my clients, so I have made no concerted effort to learn it yet. I see that the requirement you are discussing appears only under 702 (i.e., optional standby). I also see that the user gets complete freedom to determine what will be powered by the generator. My answer is that the installing electrician is the one who should be held responsible for verifying, by calculation or other approved method, that the generator has capacity.

I suspect that it won?t be too hard to comply with this new requirement. You will have a transfer switch, manual or automatic. You need not take into account anything that is not powered by a panel downstream of that ATS. In other words, you don?t have to start with a pair of SA circuits, a laundry circuit, and 3VA/ft2, as you would for a whole-house service calculation. If those things are not on the ATS-served panel(s), they don?t go into the calculation. The simplest thing to do is to add up everything downstream of the ATS, and call that the calculation. You don?t need to take advantage of demand factors, if you account for 100% of the load. If that is too much for the selected generator, however, then you need to look for any available demand factors.

At the very worst, you could ask for a signed statement from the owner, stating what they intend to power simultaneously from the generator. Add up 100% of that list of stuff, and you have your calculation. If it is too much for the selected generator, tell the owner to revise the list.
 
I don't see how this is any different then how things are now. Don't your customers have a problem if you give them a genset and it doesn't power what you said it would ?
 
nakulak said:
I don't see how this is any different then how things are now. Don't your customers have a problem if you give them a genset and it doesn't power what you said it would ?
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I think many people would put a 10 kw genset and do the entire 200 amp service and tell the homeowners to selctively choose what you will use. You cannot do this anymore. If the calculated load is 150 amps then the genset must be sized for that load.
 
I may be about to get flamed but IMHO I think that requirement is only for automatic transfer switches. The hand book commentary also seems to back this up.

Commentary to Section 702.5

This section was revised for the 2008 Code. The standby source must have the capacity to supply all of the loads connected to it, unless an automatic load management system is used to ensure that the transferred load does not overload the source. This new requirement applies only to systems where the switching between power sources occurs automatically.
 
C3PO said:
I think that requirement is only for automatic transfer switches.
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That is my understanding also.

I bet Roger tries to tell me it is only for ATS. :grin:
 
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Dennis Alwon said:
I think many people would put a 10 kw genset and do the entire 200 amp service and tell the homeowners to selctively choose what you will use. You cannot do this anymore. If the calculated load is 150 amps then the genset must be sized for that load.
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Dennis, as C3PO said, the 220 calculating is only for Automatic switching with no load management.

Roger
 
360Youth said:
NC is now under 2008 NEC as of June 1st and I am having to remind myself of that when we pull permits :rolleyes: :) . One of the code changes is, of course, sizing generators per ART 220 calculations.
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Sorry to say, but it was never allowed to automatically overload a branch circuit or feeder. Can a branch circuit or feeder supplied by normal service be overloaded? Why is it then thought of as acceptable for the generator circuit?


All 2008 does is clear up the misconception.
 
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C3PO said:
I may be about to get flamed . . . .
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Not flamed, or at least not by me. But I will disagree with you, and with those who have previously agreed with you. :cool:
C3PO said:
. . . .IMHO I think that requirement is only for automatic transfer switches.
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I disagree. There, I told you I would do it. :D
C3PO said:
The hand book commentary also seems to back this up.
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The handbook is wrong. ;) :smile:

Let’s start with the quote from the handbook, as given by C3PO in post #6. It begins with, “This section.” But it doesn’t clarify if by “this section” it is talking about all of 702.5, or just about 702.5(B)(2). All of that was revised in the 2008 version, but only a part of it “applies only to systems where the switching between power sources occurs automatically.”

The requirement for a load calculation per 220 (or other approved method) is new for 2008. It applies whether the transfer takes place automatically or manually. If the transfer is manual, there is no requirement for the generator to be able to handle all load connected to the panel that is served by the MTS. The generator need be sized only for the load that the user intends to run at the same time. You could, for example, connect both an electric range and an electric clothes dryer to the panel served by the generator. But if the owner intends to turn off the dryer before attempting to use the range, then the generator need not be sized to handle both loads simultaneously. The code does not require the owner to have any controls, interlocks, or procedures to prevent him from inadvertently running both the dryer and the range.
 
Charlie, I think we should forget the handbook commentary and look at the actual code words of 702.5(B)(2)

(2) Automatic Transfer Equipment. Where automatic transfer equipment is used, an optional standby system shall comply with (2)(a) or (2)(b).

(a) Full Load. The standby source shall be capable of supplying the full load that is transferred by the automatic transfer equipment.

(b) Load Management. Where a system is employed that will automatically manage the connected load, the standby source shall have a capacity sufficient to supply the maximum load that will be connected by the load management system.
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With out automatic load management (a) would be required.

Roger
 
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roger said:
Without automatic load management (a) would be required.
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I was not disagreeing with that. Please note that the OP was talking about Article 220 load calculations. I was disagreeing with the statement (by C3PO, in post #6) that “that requirement is only for automatic transfer switches.” I am also disagreeing with your statement, in post 9, to the same effect.

The requirement for a load calculation comes in 702.5(B), and it appears before the breakdown into a discussion of manual and automatic transfer schemes. That tells me that you need to do a calculation for a manual transfer scheme as well as for an automatic transfer scheme. Furthermore, even if you are working in 702.5(B)(2)(a), even if you will automatically transfer all connected load (i.e., all load on the panels fed from the ATS) to the generator, you still need to do an article 220 load calculation, in order to determine what loads that will be.
 
charlie b said:
The requirement for a load calculation comes in 702.5(B), and it appears before the breakdown into a discussion of manual and automatic transfer schemes. That tells me that you need to do a calculation for a manual transfer scheme as well as for an automatic transfer scheme.
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Now I see what you are saying but, If I were only going to supply one 20 amp circuit with a manual transfer switch I wouldn't bother with article 220.

Roger
 
mivey said:
Almost, the load on the 20 amp circuit would have to be calculated per article 220
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And for anyone that would care to see my proposed load, it would be for one 60 watt lamp, 220.14(A).

Roger
 
nakulak said:
I don't see how this is any different then how things are now.
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I would have to disagree. As well as with...
stickboy1375 said:
All 2008 does is clear up the misconception.
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2008 now holds the generator salesperson and/or purchaser to a new standard. Generators are, hopefully, sized for potential and probable loads. I would agree that it may not be smart to sell a generator that will handle HVAC, WH, pumps, lights, and fridge, but not cooking and drying just because the customer agrees not to use the items, but until the 2008 there was no requirement that those items be included. Customer was given that option. Now they are not.

nakulak said:
Don't your customers have a problem if you give them a genset and it doesn't power what you said it would ?
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We have never sold a generator that failed to power what we agreed upon. I seem to see this statement everytime the subject is brought up (not necessarily by me.) I totally agree that is bad business and bad work to size a generator that will not handle a potential load. That is one of the first things we emphasize to a customer, is that we are responsible to make sure the genset we sell will provide them with the power they need whether they are home, on vacation, or grocery shopping.


charlie b said:
I suspect that it won?t be too hard to comply with this new requirement. You will have a transfer switch, manual or automatic. You need not take into account anything that is not powered by a panel downstream of that ATS. In other words, you don?t have to start with a pair of SA circuits, a laundry circuit, and 3VA/ft2, as you would for a whole-house service calculation. If those things are not on the ATS-served panel(s), they don?t go into the calculation. The simplest thing to do is to add up everything downstream of the ATS, and call that the calculation.
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A great majority of what we sell is whole house. A quick survey and starting point in the past has been to get POCO records of wattage usage and take into account HVAC and other start-up loads.


charlie b said:
At the very worst, you could ask for a signed statement from the owner, stating what they intend to power simultaneously from the generator.
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I talked to an inspector today who suggested that option but I wonder how much bearing that has in releiving the EC from performing the necessary calculations.
 
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