Residential Back up Generator

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stickboy1375 said:
I don't see why the NEC would care if I tripped the main breaker on my OPTIONAL standby system...
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Neither do I.:roll: :mad:

Think of the scenario, the occupants leave the house and they turn every electric appliance on as they leave.

Then the utility fails and the generator chokes on all the load.

:rolleyes:

I see that happening all the time :roll:

Who cares if it really is not a safety issue. :rolleyes:
 
iwire said:
Neither do I.:roll: :mad:

Think of the scenario, the occupants leave the house and they turn every electric appliance on as they leave.

Then the utility fails and the generator chokes on all the load.

:rolleyes:

I see that happening all the time :roll:

Who cares if it really is not a safety issue. :rolleyes:
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Must be a Generator Pitch, to make a homeowner spend more $$$ on a bigger generator...?
 
I think it is more of a public relations issue. People pay big bucks for a "Hole House Generator". Electrican sells them a 12 kw Genset with ATS, hooks up to 400 amp service. Lots of $$$$$wire bottles in the celler. House is lived in 3 months a year. Nobody home, Power goes off, genset breaker trips, no power, no wire cooler, 98 degrees in the shade..... I think you get the picture. The REAL decision of connected load is based on Art 220.40
 
Cavie said:
I think it is more of a public relations issue. People pay big bucks for a "Hole House Generator". Electrican sells them a 12 kw Genset with ATS, hooks up to 400 amp service. Lots of $$$$$wire bottles in the celler.
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Cavie, the NEC should only be concerned with the words of 90.1(A), not wine collections. If Fl has different priorities that's sad.

I realize this will be in the 2008 NEC and that is even more sad.

I will continue to push manual means or designated panels fed from ATS's


Roger
 
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Cavie said:
I think it is more of a public relations issue. Nobody home, Power goes off, genset breaker trips, no power, no wire cooler, 98 degrees in the shade..... I think you get the picture. The REAL decision of connected load is based on Art 220.40
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NO, I do NOT get the picture at all!

This forces people to spend a lot more money on an OPTIONAL generator.
 
I am not too sure where the NFPA and the different code panels are heading in the last few code cycles. There is a trend that seems to be gathering steam in a direction that is not aligned with 90.1.
I see way too much influence by the manufacturers...just my opinion.

Maybe someone can post the ROP and the ROC for this issue for us to peruse.
 
Pierre, here is part of the ROP.

Report on Proposals A2007

— Copyright, NFPA NFPA 70

(B) System Capacity. The calculations of load on the standby source shall be made in accordance with Article 220 of by another method that is acceptable to the authority having jurisdiction.

(1) Manual Transfer Equipment. Where manual transfer equipment is
used an optional standby system shall have adequate capacity and rating for the supply of all equipment intended to be operated at one time. The user of the optional standby system shall be permitted to select the load connected to the system.

(2) Automatic Transfer Equipment. Where automatic transfer equipment is used, an optional standby system comply with a or 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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Roger
 
Here is some more

ARTICLE 702 ? OPTIONAL STANDBY SYSTEMS
____________________________________________________________
13-168 Log #2741 NEC-P13 Final Action: Accept in Principle
(702.5)
____________________________________________________________
TCC Action: It was the action of the Technical Correlating Committee that
further consideration be given to the comment expressed in the voting and
?with a or b? should be revised to read ?with (a) or (b)?.
The Technical Correlating Committee directs that the Action on this
Proposal be rewritten to comply with 4.1.1 of the NEC Style Manual.
These actions will be considered by the Panel as a Public Comment.
Submitter: Jim Pauley, Square D Company
Recommendation: Revise NEC 702.5 as shown below.
702.5 Capacity and Rating.(A) Available Short Circuit Current. Optional standby system equipment
shall be suitable for the maximum available fault short-circuit current at its
terminals.

(B) System Capacity. The calculations of load on the standby source shall be
made in accordance with Article 220 of by another method that is acceptable to
the authority having jurisdiction.
(1) Manual Transfer Equipment. Where manual transfer equipment is
used an optional standby system shall have adequate capacity and rating for the
supply of all equipment intended to be operated at one time. The user of the
optional standby system shall be permitted to select the load connected to the
system.
(2) Automatic Transfer Equipment. Where automatic transfer equipment is
used, an optional standby system comply with a or 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.
Substantiation: Due to the recent natural disasters the increase in generator
installations has grown significantly. At a number of IAEI meetings in 2005,
the question has been asked about what to do for the size of an optional
standby source that uses automatic transfer. It appears that automatic transfer
equipment is being installed with generators that have a capacity that is much
smaller than the total load (typically an entire panelboard) being transferred.
There has been significant disagreement about how the NEC treats these
automatic transfer situations.
The objective of this proposal is to try and address a number of concerns that
have been raised by both inspectors and installers. Of primary concern has
been that in an automatic transfer application, the user may not be available to
?select the loads? that will be supplied. This defeats the intent of the automatic
transfer and renders the system somewhat useless.
The proposal does the following:
1. Rearranges the existing 702.5 text to split up the paragraph and provide
headings that will make it easier for the code user.
2. Create an ?Available Short Circuit Current? heading and moves the
sentence about adequate ratings for fault current to this new heading. In
addition, the term ?fault current? is replaced with ?short circuit current? to
make it consistent with the rest of the code.

3. System capacity is now split into Manual Transfer and Automatic Transfer
applications. In addition text has been added to indicate how the load is to
be calculated. For instance if you are including the branch circuits in a home
that supply part of the general lighting load, how do you do that calculation.
The most logical approach is to use Article 220 and the new language makes
that clear. However, it is recognized that a number of jurisdictions are allow
recorded load measurements and similar information to be used to provide the
capacity. The new text would allow other methods that are acceptable to the
AHJ.
4. For manual transfer, the existing language is used to simply require that the
supply be adequate to supply the equipment intended to be connected at one
time. It also retains the existing permission for the user to be able to select the
loads that will be connected.
5. For automatic transfer, new language is provided to address the concerns
raised in the field about the user not be available to select the supplied loads.
In the automatic situation, there are a couple of options. Item ?a? provides
and option where you size the standby supply to pick up the entire load that
is being transferred. The typical application in this case is where a small
generator is connected to a new subpanel with a set number of critical loads.
Under normal power the subpanel is supplied by the normal source. When the
power fails, the subpanel is transferred to the generator source.
Item ?b? is intended to allow a system where some of the load in a larger panel
may be shed in order to reduce the loading to an adequate level to be supplied
by the standby source. We allow this in larger applications of 700 and 701, so it
makes sense here.
Article 702 has become very popular because of the number of outages that
have occurred in the country. This proposal updates the requirements to
installations that have become more common.
Panel Meeting Action: Accept in Principle
Accept the proposal as submitted except revise (B) as proposed to read as
follows

(B) System Capacity. The calculations of load on the standby source shall be
made in accordance with Article 220 or by another approved method.
Panel Statement: The editorial revision conforms to NEC Manual of Style
and corrects a typographical error.
Number Eligible to Vote: 14
Ballot Results: Affirmative: 13
Ballot Not Returned: 1 Gustafson, R.
Comment on Affirmative:
SWAYNE, R.: In Section 702.5(B)(2), editorially add the word ?shall? after
?system? to complete the sentence structure.
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Jeez Roger take your time with responding...maybe you could move your tail and get back to me faster than 5 minutes next time...:grin: :wink:

Roger, maybe you could post the substantiation of this change. I am curious as to how/why the CMP has decided this change is important enough to add to the requirements of Art 702
Thanks!!
 
What I do not see in the substantiation is any reports of actual problems, only concerns that they may be a problem.

How it is an actual electrical hazard I have no idea considering other sections of the NEC require proper OCPDs.
 
I wonder how many generator/transfer switch manufacturers had a hand in this requirement change????

I still do not see how the person cannot control the circuits. The generator trips on auto start. The homeowner goes to the panel and turns off some circuits and restarts the generator. HMMM... that is how the owner can choose which circuits, just as in the original requirements of 702 state.
 
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