Temporary Service

[don_resqcapt19]

Re: Temporary Service

Rick,

OK, In the true definition of service,these xfrmr conductors are not considered service conductors, they are feeder conductors by definition.However the overcurrent device is allowed to be as stated in (430.3(B)note 2.So in the case of xfrmr secondary conductors,either 1 MB or up to six with restictions.
I can't see why 408.36 excpt. #1 would'nt apply when 230.71 FPN is referring you to it when the service disconnect is a panelboard.whether the panelboard is fed from a feeder from a xfrmr secondary, or service conductors, the NEC is allowing it.

Article 450 has nothing to do with the overcurrent protection of transformer secondary conductors. It contains the rules for the protection of the transformer and only the transformer. The rules for the protection of the secondary conductors are found in 240.21(C). The same can be said for the original question. The rules for the required protection of a lighting and appliance branch circuit panel are found in Article 408 and not in Article 230.
Don

 

[RUWired]

Re: Temporary Service

Don ,240.21(C)1 . Xfrm "secondary conductors"are not considered protected by the primary OC device.If this is the case then, the protection is the secondary OC device.I think when they wrote "equipment" it was including conductors.240.4(F) also backs up the remark about protection of conductors.
Rick

 

[jwelectric]

Re: Temporary Service

Originally posted by RUWired:
Don ,240.21(C)1 . Xfrm "secondary conductors"are not considered protected by the primary OC device.If this is the case then, the protection is the secondary OC device.I think when they wrote "equipment" it was including conductors.240.4(F) also backs up the remark about protection of conductors.
Rick

After closely looking at the references that you posted I have come to the following conclusion;

240.4(F) addresses Transformer Secondary Conductors and their protection by the primary overcurrent device

240.21(C)(1) is addressing, (C) Transformer Secondary Conductors and (1) Protection by Primary Overcurrent Device

450.3 addresses Overcurrent protection of transformers.
Therefore note 2 of Table 450.3(A) is addressing the protection of the transformer secondary.

The deal that so many people trip over when it comes to the six disconnects allowed in 225 and 230 will have to comply with 408.36 if they are installed in a lighting and appliance panelboard.
How will they know if this is a lighting and appliance panelboard? If it has 10% or more of its overcurrent devices rated at 30 amperes or less and utilize the grounded (neutral) conductor.
Therefore a panel with one to six single pole breakers rated 30 amperes or less that uses the grounded (neutral) conductor would require no more than two means to disconnect all ungrounded (hot) conductors. A panel with one to six 15, 20 or 30 amp single pole breakers and no main would be a violation of the NEC.

 

[RUWired]

Re: Temporary Service

Mike,NOT by the primary devie.
Rick

 

[jwelectric]

Re: Temporary Service

Originally posted by RUWired:
Mike,NOT by the primary devie.
Rick

240.4(F) Transformer Secondary Conductors. Single-phase (other than 2-wire) and multiphase (other than delta-delta, 3-wire) transformer secondary conductors shall not be considered to be protected by the

PRIMARY

overcurrent protective device.

240.21(C) (1) Protection by Primary Overcurrent Device. Conductors supplied by the secondary side of a single-phase transformer having a 2-wire (single-voltage) secondary, or a three-phase, delta-delta connected transformer having a 3-wire (single-voltage) secondary, shall be permitted to be protected by overcurrent protection provided on the

PRIMARY (SUPPLY)

side of the transformer, provided this protection is in accordance with 450.3 and does not exceed the value determined by multiplying the secondary conductor ampacity by the secondary to primary transformer voltage ratio.

Which book are you reading out of?
The one I am reading clearly states the secondary conductors are protected by the PRIMARY overcurrent when it is a delta to delta.

450.3 Overcurrent Protection.
Overcurrent protection of transformers shall comply with 450.3(A), (B), or (C). As used in this section, the word transformer shall mean a transformer or polyphase bank of two or more single-phase transformers operating as a unit.

450.3 clearly states that tables 430.3(A) & (B) are for the protection of the transformer secondary.

If you can find something more than this please show me where.

[ February 19, 2006, 08:28 PM: Message edited by: jwelectric ]

 

[RUWired]

Re: Temporary Service

Jw, I thought we talking about xfrmrs that feed single phase 3-wire services.Two wire xfrmrs do not feed the panelboard in the original post that we were dicussing.also in the 3-wire to 3-wire delta xfrmr ,it is a single voltage secondary.Single phase 3-wire and 3 phase Y secondary conductors are NOT protected by the primary OC.
Rick

 

[don_resqcapt19]

Re: Temporary Service

Rick,

Two wire xfrmrs do not feed the panelboard in the original post that we were dicussing.

The power source has absolutely nothing to do with the question in the original post.
Don

 

[jwelectric]

Re: Temporary Service

Originally posted by RUWired:
Jw, I thought we talking about xfrmrs that feed single phase 3-wire services.Two wire xfrmrs do not feed the panelboard in the original post that we were dicussing.also in the 3-wire to 3-wire delta xfrmr ,it is a single voltage secondary.Single phase 3-wire and 3 phase Y secondary conductors are NOT protected by the primary OC.
Rick

You are the one who brought forward the transformer and six disconnect rule here
Transformers that supply a dwelling unit would belong to the utility company and outside the scope of the NEC.

To answer the original post as whether a temp panel with two single pole 15 or 20 amp breakers would need a main the answer is yes.

Any panel that contained 10% or more of its overcurrent devices that are 30 amps or less and utilize the grounded conductor would require no more than two mains. This would be true about sections 225.33, 230.71 and note 2 in tables 450.3(A)&(B) or any other application that you or any other person could think of.

 

[RUWired]

Re: Temporary Service

The purpose of this forum is for all of us to better understand the articles written,so that we can go out in the field and perform our work to the best of our abilities.
I do not think we are all on the same page as far as this service goes.Or maybe its just me.

230.71(A) allows the use of 1-6 switches or breakers as disconnects for the service.These can be in 1 enclosure or in seperate enclosures.

230.90(A) exception#3 allows the use of 2-6 breakers as the overcurrent protection of the service conductors.
So far all is referring to the disconnecting means and overcurrent protection.This 4-circuit enclosure in the OP is the disconnecting means and overcurrent protection for the service.
Whether the 1-6 breakers (two in this case)are disconnecting other equipment or branch circuits does'nt really matter to these articles.These 1-pole,2-pole-3pole breakers can be controlling 42 circuit panelboards, motors, or lights on a pole.
This 4-circuit enclosure is being used as a disconnecting means.(IMHO)
Rick

 

[iwire]

Re: Temporary Service

Rick I think your right, each of us has an idea in our mind that we think this thread is about.

I will try to respond directly to your last post and not get sidetracked.

I agree with you that 230.71(A) allows the use of 1-6 switches or breakers as disconnects for the service and that 230.90(A) exception#3 allows the use of 2-6 breakers as the Overcurrent protection of the service conductors.

And further I also agree that "all this is referring to the disconnecting means and Overcurrent protection. This 4-circuit enclosure in the OP is the disconnecting means and Overcurrent protection for the service."

That is just it,...so far all we have addressed is Overcurrent protection of the service conductors and disconnection of the service conductors.

We still may have to provide additional Overcurrent protection for the busbars in the panel.

What makes a difference is the classification of the panel. If the panel in question fits the definition of a lighting and appliance panelboard IT MUST have a main Overcurrent device.

If the panel is a power panel than it can be MLO with six breakers.

There is nothing in article 230 that modifies or eliminates the requirements of 408.16

Read the following to sections and see if you agree.

408.16 Overcurrent Protection.
(A) Lighting and Appliance Branch-Circuit Panelboard Individually Protected. Each lighting and appliance branch-circuit panelboard shall be individually protected on the supply side by not more than two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard.

408.14 Classification of Panelboards.
Panelboards shall be classified for the purposes of this article as either lighting and appliance branch-circuit panelboards or power panelboards, based on their content. A lighting and appliance branch circuit is a branch circuit that has a connection to the neutral of the panelboard and that has Overcurrent protection of 30 amperes or less in one or more conductors.

(A) Lighting and Appliance Branch-Circuit Panelboard. A lighting and appliance branch-circuit panelboard is one having more than 10 percent of its Overcurrent devices protecting lighting and appliance branch circuits.

(B) Power Panelboard. A power panelboard is one having 10 percent or fewer of its Overcurrent devices protecting lighting and appliance branch circuits.

Now here is the description of the panel in the first post of this thread.

4 circuit weatherproof panel with 2 20 amp breakers that feed 2 gfi receptacles below the panel.

This clearly meets the definition of a Lighting and Appliance Branch-Circuit Panelboard and therefore, regardless of 230.71(A) and 230.90(A) must be equipped with Overcurrent protection as described in 408.16.

If the 2 20 amp breakers that feed 2 gfi receptacles are removed and replaced with 2 pole 40s for example than it would be a power panel board and would not need the main.

[ February 20, 2006, 12:47 PM: Message edited by: iwire ]

 

[RUWired]

Re: Temporary Service

Bob thanks for the professional reply.Before we even get to panelboards, The disconnecting means buss bars are protected by 230.79.(IMO)If i have 480 amps of calculated load with 6-100 amp breakers on a 100 amp service, then i am in violation, and will melt the buss bars. But if i have less than 100 amps of cal.load between the 6 of them,(230.90(A) excpt.#3),then i am protecting the buss bars.In 230.79(B)If this enclosure was limited to just those two 2-wire branch circuits, then each of those breakers would have to be 30 amps, but this enclosure has a possibiliy of 4 circuits, and might be (is)in violation of 230.79(D).Since this is an others type of service.I think that just answered the question!
Rick

 

[don_resqcapt19]

Re: Temporary Service

Rick,

The disconnecting means buss bars are protected by 230.79.(IMO)

How does a calculated load provide overcurrent protection for the panel?

If i have 480 amps of calculated load with 6-100 amp breakers on a 100 amp service, then i am in violation, and will melt the buss bars. But if i have less than 100 amps of cal.load between the 6 of them,(230.90(A) excpt.#3),then i am protecting the buss bars.In 230.79(B)

You are protecting the bus bars from overloads, but not from overcurrent conditions. The rule in 408 requires supply side overcurrent protection. Note that overload and overcurrent are not the same thing. See Article 100.
Don

[ February 20, 2006, 02:34 PM: Message edited by: don_resqcapt19 ]

 

[RUWired]

Re: Temporary Service

In the search for the true meanings of these articles ,you guys are tough.I mean that in a good way!
Don,230.79(rating of the disconnect).The equipment cannot be less than the load served.This protects the bussbars from overload.
230.80....The combined rating of all the switches/breakers shall not be less than the rating of the disconnect.(this is where the 4-circuit enclosure with two 2-wire branch circuits,20 amps each are a problem.

230.90(A) exception #3 permits the 2-6 breakers as the "overcurrent device" to provide the "overload protection". The sum of all the breakers are allowed to exceed the rating of the conductors,as long as the cal.load does not.
Rick

 

[don_resqcapt19]

Re: Temporary Service

Rick,
The problem is that the panel requires overcurrent protection and you have not provided that. I agree that you have overload protection for the service conductors and the panel, but you do not have the required overcurrent protection. There is nothing in Article 230 that over rides the requirement in 408 that this panel have overcurrent protection.
Don

 

[jwelectric]

Re: Temporary Service

It has been my experience over the years that once an electrician gets a thought in his head about how something is supposed to be it is hard to get him to change..

I think that most electricians in the field today think of a panel in a dwelling unit as being the service when there is nothing between it and the meter. They can not conceive in their minds just where the service ends and the panel begins.

In a dwelling unit panel four possible points can encompass the service. 1) The load side of the main breaker. 2) The lug where the grounded (neutral) conductor lands. 3) The bonding jumper. 4) The grounding electrode conductor. The rest of this panel is a lighting and appliance panel.

When some electricians use a panel and meter base as a temp service they only see the service. For some reason they can not see that what they have installed is a lighting and appliance panel.
Section 230.71(B) has been the result of many panels being improperly installed. For what ever reason the electrician sees single pole and gets his mind set on the fact that most 15 and 20 amp breakers are single pole units therefore this is what is being talked about here. Because the term single pole breaker is used here then this is supposed to nullify the rest of the NEC. I deal with code enforcement officials that have the same train of thought.

To use this way of thinking why would any other article or section of the code apply to this service. Does it not require grounding that is found in 250 or do I just follow 250.204(D) and only provide a means for grounding for isolating switches?
To size the service conductor all that will need to be done is follow 250.23(B) and never install anything smaller than 8 copper. Could I just use 8 copper for all services?

I know that this is a little ridiculous but I hope that it helps to show that there is more than a service in the original post. He has a service that is enclosed in a lighting and appliance panel that will have to conform to 408.

 

[RUWired]

Re: Temporary Service

Don, The quote right out of 230.90(A) exception #3, "shall be" permited as the overcurrent device to provide the overload protection is stating it.

JW, Don't think for a minute that this dicussion is an indication of me being thick headed.This is all about fine tuning an understanding of an article for application. I have seen this particular set up many times in many different juristictions ,at pharmaceutical plants commercial facilities,and most recently,in the hospital that i am working at.These 6-hand rules also apply from secondaries of xfrmrs that i started talking about earlier. Not only indoor, but from primary step downs to 3-phase208 systems.This isn't just about me doing something my way, quite a few other contractors see it the way i read it.all we are dicussing is finding the language to support it.
Rick

 

[iwire]

Re: Temporary Service

Rick your right, it is common and allowed for POWER PANELS, Not for L&A panels.

The 'shall be permitted' you pointed out is in article 230 which only covers the service, not the panel which is covered in 408.

You really need to re-think your position here.

 

[don_resqcapt19]

Re: Temporary Service

Rick,

This isn't just about me doing something my way, quite a few other contractors see it the way i read it.all we are discussing is finding the language to support it.

I don't care how many people are doing it this way...it is a code violation. There is no code language to support that installation.

Don, The quote right out of 230.90(A) exception #3, "shall be" permitted as the overcurrent device to provide the overload protection is stating it.

The key point is that only overload protection is provided. The panel requires overcurrent. It is not possible to provide overcurrent protection for this panel using breakers in the panel. You need to apply the rules in both articles for this application. Again nothing in any other Chapter 1-4 Article over rides the requirement in 408.36.
Don

[ February 20, 2006, 06:50 PM: Message edited by: don_resqcapt19 ]

 

[iwire]

Re: Temporary Service

Originally posted by RUWired:
I have seen this particular set up many times in many different juristictions ,at pharmaceutical plants commercial facilities,and most recently,in the hospital that i am working at.

I would bet that all those installations meet the definition of power panels.

I install services like that.

[ February 20, 2006, 06:51 PM: Message edited by: iwire ]

 

[RUWired]

Re: Temporary Service

Yes, I will agree that a panelboard used as service equipment using the 6-hand rule can only be a powerpanel and not be a L&A panel.These previous situations mentioned earlier were in fact powerpanels.
Rick