sizing feeder

[iwire]

What do we do if the town is enforcing the 05 code. Should we start calling our customers and changing feeder?
GT

Would I be calling the customers back? .... no.

Would I change what I do in the future? ... yes.

Once I started coming to the electrical forums I learned that many things I thought I was doing correctly I was not and many things I thought where code where not. I literally just got back from a code update class and learned some new things.

 

[dcspector]

Once I started coming to the electrical forums I learned that many things I thought I was doing correctly I was not and many things I thought where code where not. I literally just got back from a code update class and learned some new things.

That is the best..and I agree 110%..:smile: "We learn and we grow"....when we stop learning ...we die.

 

[bob]

Bob, there are those that agree with you, that was why the wording was changed but the IMO the actual requirements remain the same.
Under the 2005 NEC as it was written it said 'the main power feeder'.
Any feeder that does not supply all the dwelling units load can not be 'the main feeder'.

Iwire
I'm not selling this application either way. In the past we seem to have agreed with your reasoning. I happened, in this case, to read NEC 2005 310.15(B)(6) a little closer and quoted it as reading

For application of this section, the main power feeder shall be the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

This portion of (6) seems to define the power feeder as
the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).
If you except this definition, then dual feeders and dual panels should be accepted. It likely will lie with the inspection dept. I really do not see a technical reason for the change. Large homes do have more that one panel.
Iwire, what was the problem the CMP had with this type on installation?

 

[Sierrasparky]

Hi all it's been a while.
I have a question on the same line.
In a Dwelling.
If you have a Main breaker panel with 2 sub feed breakers and no load center, are the Feeders between the Sub feed breaker and the lighting branch circuit panel still considered Main power feeder. I cannot find a rule about 100% of the Load. We still use the 2002 code.

Secondly can anyone help settle a argument. Same set-up as above.
If you are using #2 Cu NM cable for that feeder is it rated at 95 amps?
Does it get a 100 amp breaker or a ?

From the 2002 code can you use #2cu SER cable at 125 amps
Thanks

 

[GThomas23]

I can't find the rule about 100% of the load either. Our area is on the 05 code and its not in their. Can someone point this out to us.
GT

 

[Sierrasparky]

So in the 2008 code they reduce the ampacity of ser cable? I don't have a 2008 book. we use the 2002 here in Ca. It's amazing that folks think we are so strict on building codes here. WE are so far behind.

I thinkk the 2008 code is rediculous on this if it is so. anyone look at the feeder size the poco installs lately?
I put 4/0 AL SER for a 200 amp service. Then they tie into it underground with a #1 AL How does that work.
Load diversity hogwash. How do you explain 100' of poco #1 then to my main then 20' to the main loadcenter. and a max ambient temp in the basement of 55 deg F?

 

[iwire]

Iwire
I'm not selling this application either way. In the past we seem to have agreed with your reasoning. I happened, in this case, to read NEC 2005 310.15(B)(6) a little closer and quoted it as reading This portion of (6) seems to define the power feeder as
the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

It is interesting that you chose to leave out the word main.

For application of this section, the main power feeder shall be the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

If it is the 'main' it has to take all the load, not just part of the load.

I really do not see a technical reason for the change. Large homes do have more that one panel.

IMO Load diversity.

If the feeder supplies 100% of a dwelling unit load the CMP knows that due to Article 220s calculations that the feeder will not be overloaded.

On the other hand if you had a 400 amp service that supplies two 200 amp feeders to two 200 amp panels all bets are off.

Lets say the home is electric heat and the EC decided to place all the heating loads in one 200 amp panel and all the other loads in the second panel. Now there is little to no load diversity in the heating panel.

Iwire, what was the problem the CMP had with this type on installation?

The ROP is long and I will post it if you want but here are parts of it.

6-61 Log #194 NEC-P06 Final Action: Accept in Principle
(310.15(B)(6))

Panel Meeting Action: Accept in Principle

Remove the 2 sets of parentheses and the duplicate ?s? on panelboards so that the section reads

Panel Statement: The panel agrees that the present wording is ambiguous. It is the panel?s intent that this allowance apply only to conductors carrying 100% of the dwelling unit?s diversified load.

Notice they say 'ambiguous' I take that to mean the sections intent has always been as it is now in the 2008 but as written had left some unintended wiggle room.

 

[iwire]

I can't find the rule about 100% of the load either. Our area is on the 05 code and its not in their. Can someone point this out to us.
GT

For application of this section, the main power feeder shall be the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

If it is the 'main' it has to take all the load, not just part of the load.

 

[Sierrasparky]

If it is the 'main' it has to take all the load, not just part of the load.

SO how does that apply to the 2002 ,0r 2005 code.
As I see it it allows for multiple feeders and panels. Each panel cannot hold 100% of the load..

 

[A/A Fuel GTX]

Don't forget that under the 2008 NEC SER would have to be used at 60C.

Bob....Can you cite a code reference to this? I don't see it in 338.

Noalox is optional.

Not in my area.....

 

[iwire]

SO how does that apply to the 2002 ,0r 2005 code.
As I see it it allows for multiple feeders and panels. Each panel cannot hold 100% of the load..

It applies to the 2002 and 2005 because in those code cycles it requires it to be the main.

For application of this section, the main power feeder shall be the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

A feeder, supplying a subpanel is not a main feeder.

 

[iwire]

Bob....Can you cite a code reference to this? I don't see it in 338.

There is no code article that actually requires the use of Nolox.

110.14 is as close as it gets.

Once in a while manufacturers instructions require it then 110.3(B) kicks in.

 

[A/A Fuel GTX]

Bob.....What about having to use the 60C column for SER ampacity. I thought XHHW was listed in the 75C column.....I'm confused.

 

[iwire]

Bob.....What about having to use the C column for SER ampacity. I thought XHHW was listed in the 75C column.....I'm confused.

For services nothing has changed, but when using SE for feeders and branch circuits in place of NM things have changed.

338.10(B)(4)(a) has been changed and now says SE used inside in place of NM must comply with all of Part II of 334. That includes 334.80 which limits us to 60 C. Under the 2005 and before 334.80 was excluded from SE.

 

[A/A Fuel GTX]

Thanks......I wasn't aware of the change.

 

[Sierrasparky]

It applies to the 2002 and 2005 because in those code cycles it requires it to be the main.



A feeder, supplying a subpanel is not a main feeder.

so how do you account for a meter/main then remote branch circuit lighting panel(S) You can get a main breaker panel with four spaces . You can install 2 100's or 1 200 .
Either one is a main breaker

I see nothing in the 2002 code about 100% of the load. Could you show me please...
Our entire county is doing it wrong...

 

[iwire]

so how do you account for a meter/main then remote branch circuit lighting panel(S) You can get a main breaker panel with four spaces . You can install 2 100's or 1 200 .

The single 200 could use 310.15(B)(6), the two 100s would have to use 310.16

I see nothing in the 2002 code about 100% of the load. Could you show me please...

I have shown you the code making panels statement ...

Panel Statement: The panel agrees that the present wording is ambiguous. It is the panel’s intent that this allowance apply only to conductors carrying 100% of the dwelling unit’s diversified load.

I can also say take a look at the wording in the 2008 NEC 310.15(B)(6).

For the application of this section, the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling unit.

Now we can dispute what the rule was in 2002 and 2005 as it could be interpreted either way. But that dispute ends in 2008 and based on the code making panels statement we now know how the 2002 and 2005 wording should have been interpreted.

Our entire county is doing it wrong.

Don't worry, many areas where enforcing this section wrong, that is why it has been changed.

 

[Sierrasparky]

Bob
so you really think we all have been doing it wrong prior to the 2002 code?

 

[bob]

It is interesting that you chose to leave out the word main.

It was not left off intentionally. My quote was as follows:

This portion of (6) seems to define the power feeder as
the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

If I add "main" back the the quote is reads

This portion of (6) seems to define the main power feeder as
the FEEDER(S) between the main disconnect and the lighting and appliance branch circuit PANELBOARD(S).

I don't see that it makes a difference. If the CMP wants make the change, they did it in the 2008 version. No question on the intent.

If it is the 'main' it has to take all the load, not just part of the load.

Have not found that in the book yet.

 

[iwire]

Have not found that in the book yet.

Bob how can a "Main Power Feeder" supply anything less then the entire load?

If it supplies only part of the load it is not "the main power feeder", it is something less then the 'main'. Heck even Mr Beck agrees on this one.

It's like looking at a partially filled glass of water and saying it's full.

Regardless it's clear under the 2008.