Small generator

[walkerj]

I need a K-6010 for a 200 amp CH

 

[jwelectric]

Mike, IYO, when must the calculation take place?
Roger

In 702 it tells us that the load is to be calculated so I would think that it would be required to be done before the inspection.

 

[iwire]

In 702 it tells us that the load is to be calculated

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

:smile:


In the ROP the CMP mentioned that recorded load measurements and similar information could be used to provide the capacity. Recorded load information is not a calculation it is a measurement.

Similar information could be whatever the AHJ decides it is.

 

[roger]

In 702 it tells us that the load is to be calculated so I would think that it would be required to be done before the inspection.

Mike, if there is no generator sitting in the garage at the time of the inspection, what happens?

Roger

 

[jwelectric]

No Mike it does not say a calculation must be made, a calculation is one way. Again, a calculation or other approved methods, the other approved methods do not have to include any calculations.

(B) System Capacity. The calculations of load on the standby source shall be made in accordance with Article 220 or by another approved method.

Let me see if I understand what this section is saying. It says that a calculation shall be made and you can use Article 220 or you can use another method to make this calculation but the calculation shall be made.
I don?t see anything that says anything different do you?

And how is that different from that same person plugging in their life safety equipment and say a space heater on the same branch circuit?

Well Bob I bet with a little thought you can see the difference between a tripped circuit and a power failure.
I would also wager that if you were the one on that oxygen concentrator that you would be saying something about wanting to know in your heart that the generator didn?t fail.

It is real easy for us to say that a 13kw generator will carry 54 amps and know what will and will not work but then again we aren?t the ones flopping around like a fish out of water when there is no power.

 

[augie47]

Lot of folks don't like "real world" situations. I'm with Roger..when we speak of the average homeowner that has added a smalll generator or provisions for a small genertaor with some type manual transfer, especially
"breaker interlock" on a main panel. 702.5(B)(1) is a waste of ink.
I'm proud to see (B)(2) and I think in an "autoomatic" transfer situation there should be some assurance that the load won't overload the generator.
With the "normal" small unit/manual transfer installs I see, I'm proud to see the homeowner/electrican call for an inspection and assure there is some type transfer. It beat he** out of the "back wired dryer plug".
Situations vary from inspection area to inspection area, but in my world I will let the homeowner "select" his load as he wishes and thank him for allowing us the check the safety of the system otherwise.
The CMP rooters can take a higher road if desired, but to me, 702.5 is a step in the right direction and I will work with it using some "real" input.

 

[iwire]

I don?t see anything that says anything different do you?

I told you and showed you what I see, I also showed that the CMP writing the section acknowledges that ways without calculations can be allowed.

Well Bob I bet with a little thought you can see the difference between a tripped circuit and a power failure.

No I see no difference in electrical safety at all.

I would also wager that if you were the one on that oxygen concentrator that you would be saying something about wanting to know in your heart that the generator didn?t fail.

Just like I would not want the branch circuit to fail, but if my life depends on the continuous supply of 125 VAC I had darn well better have some back up plan. Generators fail, fuel runs out, circuits have shorts.

It is real easy for us to say that a 13kw generator will carry 54 amps and know what will and will not work but then again we aren?t the ones flopping around like a fish out of water when there is no power.

And just who is flipping around like a fish without power?

 

[jwelectric]

Bob I understand your point of view and have even been there and done that in days gone past.

What you posted is simple:
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.

Now I bolded a part of what the CMP had to say and it leads more toward what the verbiage of the 2008 NEC states now which is:

(B) System Capacity. The calculations of load on the standby source SHALL BE MADE
1- in accordance with Article 220
2- or by another approved method.

It does not say that the load can be changed at the will of the end user by turning off one circuit and turning on another circuit.
This is the standard of practice found throughout the electrical world and is nowhere near the verbiage found either in neither the NEC nor the ROP.
In both the ROP and the NEC it is very clear that some sort of measurement has to be made to determine the size of the generator in order to keep it from being overloaded.

We as electricians have for years taken the sentence, ?The user of the optional standby system shall be permitted to select the load connected to the system? to mean that one circuit can be turned off so another circuit can be turned on when the sentence right in front of that sentence clearly makes the statement that the system is required to be sized to the load that is connected to that system.
This sentence simply means that there is no legal requirement that any circuit be installed on an optional standby system and what ever the end user wants to be connected can be connected. It doesn?t mean that one circuit can be turned off so another circuit can be turned on.

This is not such a problem in commercial and industrial installations as it is in residential installations and Article 702 addresses all three of these installations. In the residential setting I think that we are giving the end user far too much credit of their knowledge to say it is okay to turn this circuit off so this circuit can be turned on.
I don?t believe this is what the code panel had in mind when they say that the end user can choose what they want to be connected to the optional system either.
I can?t find one word that would substitute this train of thought. What I see is that the end user can choose what they want to connect to the transfer switch as long as it is not more than the generator is designed to carry safely.

In both 700 and 701 there are certain circuits required to be connected to the system. These circuits are required to be handled through the transfer of current form the normal power to the standby power.

In 702 there is no requirement that any circuit be connected to the transfer switch and the end user of the equipment gets to choose what they want to have connected to this transfer switch. It does not say that the end user can pick and choose at will what they want to have on at any certain time and this would be hard to do and comply with 702.5(B).

Now with this I shall leave you and the others to do as you please as this is what you are going to do in the first place but I do hope that I have at least got someone to thinking about connecting a small generator to a 200 amp panel and thinking that the homeowner is not going to have some serious problems trying to keep it running.

I can honestly say that over the past few years I have been involved with no less than 10 small generators and manual transfers that just wouldn?t do what the homeowner was told they would do. In each case the generator was pushed past its limits. In each case there was a dissatisfied homeowner that had spent a small fortune hoping that he could stay warm, cook, watch TV and take a bath but atlas none of this happened although all this was in the panel that was transferred to the generator.

I ask who is to blame, homeowner who spent all this money or the professional that they put their trust in to make the installation?

 

[iwire]

Mike I stand by what I have said.

You can make it red, you can make it big, you can make it long, you can even try to talk down to me but I still see it differently then you do.:smile:

 

[don_resqcapt19]

We need an english major. I think that the way the sentence is structured, that both the phrase "in accordance with Article 220" and the phrase "by another approved method" apply to the word "calculations". I have to agree with Mike that the rule requires calculations.

 

[Pierre C Belarge]

In the 2008 cycle, there has been clarification as to the load connection to the generator.
Lets stay away from the automatic transfer switch, I see that as written well enough to be complied with the "design/thought" of the CMP.

For non-automatic transfer switches or even interlocks, etc... generators are still basically installed/designed as has been in the past.

The owner/user gets to decide - and decide at any point in time, even after the installation has taken place, which circuits they desire as important to be supplied by the generator... even if it means the generator will stall.

Article 702 is for optional standby systems. If the customer has life safety devices connected to the system and it is still deemed an Art 702 installation, then it is the customer's responsibility to make sure the installer understands this. It can then be decided how much the customer will spend to make sure that their needs are met. That is a design choice, not a code issue.

 

[iwire]

We need an english major. I think that the way the sentence is structured, that both the phrase "in accordance with Article 220" and the phrase "by another approved method" apply to the word "calculations". I have to agree with Mike that the rule requires calculations.

I still do not see it that way, there is an "OR" in there that surly means something. :smile:

And taken with the CMPs statement the intent is clear.

 

[Twoskinsoneman]

I still do not see it that way, there is an "OR" in there that surly means something. :smile:

And taken with the CMPs statement the intent is clear.

Common iwire. The sentence clearly says calculation have to be done by option one OR option 2. However I agree with Roger. When it comes to manual transfer the other approved means may have to be trial and error.

Mike, what (practically) has to happen if a HO wants to install a gen and main interlock transfer switch. Do they have to promise to only turn on CBs that were part of the calculated load?

 

[iwire]

Common iwire. The sentence clearly says calculation have to be done by option one OR option 2. However I agree with Roger. When it comes to manual transfer the other approved means may have to be trial and error.

Are you disagreeing with me or agreeing with me? :-?

I feel Roger and I are pretty close to the same view.

The CMP states that one of the approved methods may be a load reading, that is not a calculation.

You tell me what calculation you envision that does not include Article 220?

 

[jwelectric]

I still do not see it that way, there is an "OR" in there that surly means something.

And taken with the CMPs statement the intent is clear.

Well we do agree here and I would think that using a power bill would be a calculation that the power company has already done for us.
At any rate the calculation has to be made.

The CMP states that one of the approved methods may be a load reading, that is not a calculation.

Then pray tell us just what it is if it is not coming up with a load? Both give us the same results and is an approved method that is found in Article 220.

You posted the remarks by the TCC concerning how the load calculation is to be done;

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.

Their statement clearly states in the first sentence that a load is to be calculated. In their third sentence they mention the use of a load reading.

No one is talking down to you in any way but I am trying to get you to see that the statement is clearly made that some sort of calculation is to be made.

As you have said many times, it is what it is.

 

[iwire]

Then pray tell us just what it is if it is not coming up with a load? Both give us the same results and is an approved method that is found in Article 220.

The load can be determined by crystal ball or any other method that is acceptable to the AHJ.

Here is an installation I did last May under the 2008 NEC it left me, the customer and the inspector all with a warm fuzzy feeling. :smile:

I can not remember the KW of the genset but it certainly could not run everything in this large home, this main panel powers at least two sub panels, a steam generator, a pool central AC etc.

The owner is fully aware that he has to be selective when running the generator.

IMO I have not violated any NEC Article nor have I short changed this customer.

 

[stickboy1375]

This is a nonsense thread. You cannot control what the homeowner is going to do after you leave, fixed loads are almost NON-existent in residential, Doing ANY type of calculation is completely useless.

 

[stickboy1375]

The load can be determined by crystal ball or any other method that is acceptable to the AHJ.

Here is an installation I did last May under the 2008 NEC it left me, the customer and the inspector all with a warm fuzzy feeling. :smile:

I can not remember the KW of the genset but it certainly could not run everything in this large home, this main panel powers at least two sub panels, a steam generator, a pool central AC etc.

The owner is fully aware that he has to be selective when running the generator.

IMO I have not violated any NEC Article nor have I short changed this customer.

Exactly the way I do them as well when many subpanels are involved and supplied by a portable generator. Nice job!

 

[Twoskinsoneman]

Are you disagreeing with me or agreeing with me? :-?

I feel Roger and I are pretty close to the same view.

The CMP states that one of the approved methods may be a load reading, that is not a calculation.

You tell me what calculation you envision that does not include Article 220?

Well I agree with you and Roger. And I like the addition of the CMP. But I felt that when you disagreed with Don's break down of the verbage
("I still do not see it that way, there is an "OR" in there that surly means something.") you may have been intentionally obtuse.

Does this really come down to what is a clculation? Is a load reading a calculation? Sure. So yes a calculation has to be done and yes it can be done by other means. Other means being undefined except that it must be approved.

 

[Twoskinsoneman]

This is a nonsense thread. You cannot control what the homeowner is going to do after you leave, fixed loads are almost NON-existent in residential, Doing ANY type of calculation is completely useless.

You know I agree 100%. The verbage IMO says what it says but as far as I am concerned iwire's install is typical and fine. IMO the AHJ approved a dynamic load calculation to be done by HO