250.122(B) Increase in size - were did the change come from.

[Sierrasparky]

Ok know we are on a dedicated thread.

What I would like to know is how did the interpetation go from upsizing when having long runs and voltage drop to where it has been in the last few cylces?

I read in another thread it was due to lack of enforcement. I say hogwash.
I have read the ROP from others and Dennis Alwon. I don't agree with the angle those folk are looking at. Sorry Dennis.

We have an debate going on another thread where this rule could cause unnecessary upsizing of wire due to the current and proposed language. If the intent is really all about upsize due to long distance runs then we need to keep focus on that point. This point regardless of claims of lack enforcement shall maintain of greatest importance.

The ramifications of the code as written have not yet been realized by most yet as they are un aware of the original interpetation.

The next thing we will be doing is ripping out oven circuits in homes because the owner chose to go Gas or a combo and the circuit now needs to be 20 or 30 Vs 50. How many of you code compliant people are going to break the law. Or maybe loose work to a misinformed contractor or Handyman.
If I can't use this info to make comment on the 2014 NEC at least I can try with the California Electric code wich is a later version.
I think this is a good start.

 

[iwire]

The ramifications of the code as written have not yet been realized by most yet as they are un aware of the original interpretation

And yet you do know?


If you are that peeved by the rule put in a change proposal.

 

[Sierrasparky]

I am peeved enough.
What need to know is what were the previous methods attempted. I am new to creating a change like this. The panels seem very arbitrary. One needs to know were this code has traveled before in order to attempt a change.

 

[infinity]

Start with the past and current (2014) ROP's.

 

[Sierrasparky]

Start with the past and current (2014) ROP's.

I have looked at the 2014 and I don't like the angle they are comming from.
The position targeting long runs or voltage drop is not even mentioned. I need to know what failed previously to try to do something different. Some of you where around back in the day way before I was a member when this first went sour. I'd like to know more about back then ( 2000- 2005)

 

[don_resqcapt19]

I have looked at the 2014 and I don't like the angle they are comming from.
The position targeting long runs or voltage drop is not even mentioned. I need to know what failed previously to try to do something different. Some of you where around back in the day way before I was a member when this first went sour. I'd like to know more about back then ( 2000- 2005)

Go to the NFPA website and download the ROPs and ROCs from the previous code cycles. Use the drop down to go to the year you want and then click on archived revision information.

 

[augie47]

.....treading softly.... I don't pick up on the change that has you concerned. Can you elaborate.

 

[charlie b]

What I would like to know is how did the interpetation go from upsizing when having long runs and voltage drop to where it has been in the last few cylces?

I don't know the history. But I suspect that when the code only required upsizing the EGC when the ungrounded was upsized for voltage drop reasons, any number of installations did not include upsizing the EGC because the installer claimed the ungrounded were upsized for reasons other than voltage drop. All an installer would have to say is that the larger conductors were all he had in the truck that day, and suddenly the requirement for upsizing the EGC did not apply. I have never agreed with the technical basis for this rule, but I would not want any technical merit it might have to be so easily circumvented.

 

[Sierrasparky]

I don't know the history. But I suspect that when the code only required upsizing the EGC when the ungrounded was upsized for voltage drop reasons, any number of installations did not include upsizing the EGC because the installer claimed the ungrounded were upsized for reasons other than voltage drop.

All an installer would have to say is that the larger conductors were all he had in the truck that day, and suddenly the requirement for upsizing the EGC did not apply. SO WHAT! , If it's a short distance what is the ramifications. ( less than 10-20 feet)



I have never agreed with the technical basis for this rule, but I would not want any technical merit it might have to be so easily circumvented.

5- 264 - (250-122): Accept
SUBMITTER: Jamie McNamara, Hastings, MN
RECOMMENDATION: Revise to read as follows:
250-122 (b) Increased in size Adjustment for Voltage Drop. Where ungrounded conductors are increased adjusted in size to compensate for voltage drop, equipment grounding conductors, where installed, shall be increased in size adjusted proportionately according to circular mil area of the ungrounded conductors.
SUBSTANTIATION: The current text is limited to voltage drop only and is subject to abuse and misinterpretation (e.g. it was done per the plans, not for voltage drop). The manufacturers
directions often call for conductor to be increased in size, with no explanation for why the ungrounded conductors size is increased, with no corresponding requirement for the equipment
grounding conductor to be increased.
PANEL ACTION: Accept.
red = text to be deleted
blue = new text

Thanks, I saw that ROP last night in my searches. So we have a union clout person by the name of Jamie McNamara,of Hastings, MN to blame for this. He states for this change " because of abuse" What does one call what we have today. " confusion " "sillyness" and "abusive rule". I'd like to really know what his pet peve was really about?

This change was made in 2002 NEC and some are here learning for the fist time what the ramifications are. Just on that point alone this is not written properly. Clear and concise language and intentions are my motto.

 

[don_resqcapt19]

... So we have a union clout person by the name of Jamie McNamara,of Hastings, MN to blame for this. He states for this change " because of abuse" ...

What are you trying to say here?????????????????????????????????????

 

[Sierrasparky]

What are you trying to say here?????????????????????????????????????

Sorry if I think this guy had a Axe to grind. And He had the Ear of the panel.
This went into effect in the 2002 code cycle. There have been several unsuccesful attemtps to correct the problem. If there is a engineering problem with a upsize of wire in short legnths that have and will result in life safety issues then I will stand down. All this rule is doing is creating unnecessary confusion, work and potential lawbreakers who otherwise would comply. :rant:

 

[don_resqcapt19]

Sorry if I think this guy had a Axe to grind. And He had the Ear of the panel.
This went into effect in the 2002 code cycle. There have been several unsuccesful attemtps to correct the problem. If there is a engineering problem with a upsize of wire in short legnths that have and will result in life safety issues then I will stand down. All this rule is doing is creating unnecessary confusion, work and potential lawbreakers who otherwise would comply. :rant:

This was nothing more than an ispection/enforcement issue. The orginal wording was not enforceable. I think most of the attempts to change have not been to restore the "voltage drop" rule, but to more clearly define what is the normal size conductor.


You need to go back and look at when the rule first went in and look at the technical merits of the rule. I am not sure there were any.

 

[BPoindexter]

I find it interesting that there is no technical backing for the change in the 2014 language instead it is non-specific citations of abuse. So if as it stands taken to it's logical completion, and applying this as some do, you could have this scenario:

24A circuit normally requiring #10 conductors and using a 30A OCPD. Beacuse of conduit fill and ambient temperature you now have to upsize to #8 for the ungrounded conductors. According to the new language you now have to also upsize the EGC which now means that it requires a #8 EGC? However in the adjacent conduit you have 3 #6 ungrounded conductors on a 60A OCPD and using a #10 EGC as required by 250.122

IEEE 141 is the grounding standard upon which much of the NEC requirements are derived. There are 3 performance requirements that must be met for equipment grounding:

1) To reduce electric shock hazard to personnel.

2) To provide adequate current carrying capability, both in magnitude and duration, to accept the ground-fault current permitted by the overcurrent protection system without creating a fire or explosive hazard to building or contents.

3) To provide a low impedance return path for ground-fault current necessary for the timely operation of the overcurrent protection system

The reason for increasing the size of the EGC in the case of voltage drop is to meet requirement #1. If you are upsizing in to order to correct for voltage drop then:

The impedance of the grounding conductor must be low enough to accept the available line-to-ground-fault current without creating a hazardous impedance (IZ) voltage drop. The available ground-fault current of the supply system will have a direct bearing on the equipment-grounding conductor requirements.

Table 250.122 is designed to make the installation meet the requirements including requirement #2. This is based on the withstand rating (I^2T) of the conductor. If there are excessive fault currents available that exceed the EGC's withstand then you must oversize per 250.4(A)(5). If installed correctly and sized per 250.122 the you will meet all of the requirements.

The way that I personally apply the 250.122(B) requirement is that if the ungrounded conductors are upsized but are still less than than the Max OCPD for the EGC per 250.122 then I do not upsize. For example a #6 CU is good for up to a 200A OCPD. So if I had a 125A Circuit, requiring #1 CU, but had to upsize the ungrounded conductors to 1/0 CU for derating then I would still use a #6 CU. Otherwise you could end up with situation described above where you have #8 CU for both ungrounded and EGC conductors.

As to the new wording I believe that while it may appear good on the surface it is bad science, technically flawed, and will cause much confusion, uneccessary work, and cost.
My 2.78 cents worth

 

[Sierrasparky]

Thanks Don, your input helps me and I hope others understand were we were and were we are now.

As I opined before I don't agree that a change of such nature was necessary due to lack of enforcement. The informed inspector could request that the EGC size was appropriately sized to open in a fault event. I believe there is a code section for that too.

The current Draft 2014 adds the language " from the minimum size that has sufficient ampacity for the intended installation " This would further complicate things.



Please you or others correct me if I am wrong. Lets take an obvious scenario used in a residential remodel.
You have an electric range converted to Gas. You use the 220/ 40 amp cir to add two more 120v circuits to power a built in Micro and take some load off the existing counter circuits. Or maybe you just want to convert the outlet to supply a 120v igniter. The circuit length is no more than 40' but the average instance is 20'.

Does this circuit impose a fault hazard. In my opinion no. I'd like an engineer to chime in.
If this type of circuit is unsafe as I said earlier I will stand down.

 

[don_resqcapt19]

Thanks Don, your input helps me and I hope others understand were we were and were we are now.

As I opined before I don't agree that a change of such nature was necessary due to lack of enforcement. The informed inspector could request that the EGC size was appropriately sized to open in a fault event. I believe there is a code section for that too.

The current Draft 2014 adds the language " from the minimum size that has sufficient ampacity for the intended installation " This would further complicate things.

I think that does act to clarify the code rule.

Please you or others correct me if I am wrong. Lets take an obvious scenario used in a residential remodel.
You have an electric range converted to Gas. You use the 220/ 40 amp cir to add two more 120v circuits to power a built in Micro and take some load off the existing counter circuits. Or maybe you just want to convert the outlet to supply a 120v igniter. The circuit length is no more than 40' but the average instance is 20'.

Does this circuit impose a fault hazard. In my opinion no. I'd like an engineer to chime in.
If this type of circuit is unsafe as I said earlier I will stand down.

Of course it is safe, but tell me how you would write the rule so it works all the time.

 

[Sierrasparky]

I think that does act to clarify the code rule.[/FONT][/FONT][/SIZE]


Of course it is safe, but tell me how you would write the rule so it works all the time.

You're kidding, Yes!

The scenario I mention is most likely the norm. Short distances under 75' and mainly under 25'. First I would determine where the cutoff from properly operating overcurrent device ends and safety becomes an issue. Have a engineer run the numbers and validate by his peers. Once we see the curve a length not to exceed could reasonably be established. If left as is, a EC is being penalized for installing a more expensive wire when the acutually needed.
Pretty simple actually.


NEC is not supposed to be legislating morality.

 

[charlie b]

The current Draft 2014 adds the language "from the minimum size that has sufficient ampacity for the intended installation." This would further complicate things.

I have been trying to get the CMP to add something like this to the code for years. My problem was that for something to be ?increased in size,? you have to know what the starting point was (i.e., ?increased from what to what??). The CMP?s problem has always been to make the rule easy to understand, easy to follow, and easy to enforce, without making it so long that it starts getting confusing again. I am glad to see they finally found wording that they can live with.

Here is an example of the thing that I think is wrong with the current (2011) rule. Put five 20 amp circuits (2-wires each, no shared neutrals) in the same conduit. Let us say that the load on each is calculated at 16 amps, all continuous. Thus, a 20 amp wire and a 20 amp breaker will suffice for each circuit. But if you tried to use #12 THHN, the ampacity would have to be derated to 15 amps (i.e., 50% of the 90C rating of 30 amps). So in order to use 20 amp breakers, you need to use #10 wire (with its derated ampacity of 20 amps). Question: does using a #10 on a 20 amp circuit constitute an increase in size, and do you therefore need to upsize the EGC to #10? I think not, simply because we would not be allowed to use a #12. The minimum acceptable size is #10, and that is not an increase. The new wording makes it clear that if you are using the smallest allowable size wire for the ungrounded conductor, then this does not count as the wire being ?increased in size,? and therefore you do not need to increase the EGC.

 

[charlie b]

You have an electric range converted to Gas. You use the 220/ 40 amp circuit to add two more 120v circuits to power a built in Micro and take some load off the existing counter circuits. Or maybe you just want to convert the outlet to supply a 120v igniter. The circuit length is no more than 40' but the average instance is 20'. Does this circuit impose a fault hazard? In my opinion no. I'd like an engineer to chime in.

I would chime in, but you didn?t finish your description of the question. So I will try to fill in the blanks.

The original 40 amp, 220 volt circuit probably used #8 wire, and #10 EGC. When you convert this to a pair of 20 amp circuits, you now have a 20 amp breaker, with #8 ungrounded conductors. If that were a newly installed circuit, then regardless of your reason for selecting #8 wire for the ungrounded, 250.122(B) would require you to use a #8 EGC. Therefore, keeping the original #10 EGC would be a violation. You are now asking whether that would be a safety hazard, or just a violation of the literal wording of the code article.

My opinion is that this would not be a safety hazard. So I agree with you here. But as I already said, I never agreed with the technical basis for this rule anyway.

 

[Sierrasparky]

Charlie I see your point. I'll give another. So now you have a #10 because of conductor heating derating. How long a run can you make with the #10's on a 20 amp breaker before you run into fault issues because you have only a #12 EGC.



To make matters worse is the minimum size EGC in a conduit with multiple circuits safe anyway in the event a conduit and its conductors are severed?

Anyway, I see that as long as the CMP feels warm and cozy with a ROP then it's a done deal.

 

[don_resqcapt19]

You're kidding, Yes!

The scenario I mention is most likely the norm. Short distances under 75' and mainly under 25'. First I would determine where the cutoff from properly operating overcurrent device ends and safety becomes an issue. Have a engineer run the numbers and validate by his peers. Once we see the curve a length not to exceed could reasonably be established. If left as is, a EC is being penalized for installing a more expensive wire when the acutually needed.
Pretty simple actually.


NEC is not supposed to be legislating morality.

Show me the words that you would put in the NEC to do that. You really want to write a code rule that requires the EC to hire a PE to tell you what size EGC you need?