Outside Taps of Unlimited Lentgth 240.21(B)(5) and Equipment Grounding Conductors

[cohosilver]

How are equipment grounding conductors sized using the unlimted tap rule if 240.21(B)(5)?

I read in 240.21 that "Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specificed in 240.42(A) through (H)."

Since the conductors will terminate at a single circuit breaker or set of fuses, is the equipment grounding conductor that is run with the taps allowed to be sized by T250.122 based on the overcurrent device where the feeds terminate?

Is there something specific that states this? Or is it just how it is interpreted?

 

[don_resqcapt19]

EGCs for 240.21(B) taps are sized based on the upstream OCPD with the limit that the EGC is not required to be larger than the circuit conductors. See 250.122(G).

 

[infinity]

Although not an outside tap here's a good example of sizing the EGC (incorrectly) for the OCPD at the end of the tap.

 

[kwired]

Although not an outside tap here's a good example of sizing the EGC (incorrectly) for the OCPD at the end of the tap.

In that installation I would have a harder time with the "not larger than the tap conductors" part of the rule since the feeder is in the same enclosure as the overcurrent device at the end of the tap, that enclosure needs to be grounded with a bonding jumper sized for the feeder whether there is a tap or not. Looks like the photo maybe has a 200 amp feeder with a 60 amp tap. The same size as taps works here, but lets say it were a 400 amp feeder, then a 6 AWG bonding jumper to the enclosure is too small because of the feeder being in the enclosure.

 

[david]

Interesting, I can?t see what size the breakers is for the tap say 100 amp maybe. But in this example it doesn?t mater the tap is in the same cabinet so it needs an equipment bonding jumper to bond the cabinet based on the size of the equipment bon running with the feeder.

I?m not sure this is a good example to help clarify the op questions but you did make me think for a minuet or two on this one.

 

[Dennis Alwon]

Interesting, I can?t see what size the breakers is for the tap say 100 amp maybe. But in this example it doesn?t mater the tap is in the same cabinet so it needs an equipment bonding jumper to bond the cabinet based on the size of the equipment bon running with the feeder.

I?m not sure this is a good example to help clarify the op questions but you did make me think for a minuet or two on this one.

David if the tap is say from a 300 amp breaker and the tap conductors are 100 amps then you are required to size the EGC by Table 250.122 for the conductors ahead of the tap-- that would be 300 amps. This requires a #4 copper conductor. If per chance the tap conductors were smaller than what is required by 250.122 then you only need to be as larger as the tap conductors.

So if the tap conductors could be #8 but the egc required by T. 250.122 required a #6 then you only need the egc to be sized at #8.

 

[don_resqcapt19]

David if the tap is say from a 300 amp breaker and the tap conductors are 100 amps then you are required to size the EGC by Table 250.122 for the conductors ahead of the tap-- that would be 300 amps. This requires a #4 copper conductor. If per chance the tap conductors were smaller than what is required by 250.122 then you only need to be as larger as the tap conductors.

So if the tap conductors could be #8 but the egc required by T. 250.122 required a #6 then you only need the egc to be sized at #8.

I think that David's point is that 250.148 applies and the connection to the enclosure must be full sized based on the feeder OCPD, even if that results in a EGC tap that is larger than the tap conductors.

 

[Dennis Alwon]

I think that David's point is that 250.148 applies and the connection to the enclosure must be full sized based on the feeder OCPD, even if that results in a EGC tap that is larger than the tap conductors.

I agree if that is at the tap junction. But if the tap conductors terminate in a breaker enclosure or other JB then the bond would only need to be the size of the EGC. Am I wrong? I thought this is what he was talking about.

 

[don_resqcapt19]

I agree if that is at the tap junction. But if the tap conductors terminate in a breaker enclosure or other JB then the bond would only need to be the size of the EGC. Am I wrong? I thought this is what he was talking about.

In the pictures the tap was made in the breaker enclosure and I would agree with David that the EGC tap to the enclosure must be full sized based on the feeder OCPD size.

 

[Dennis Alwon]

In the pictures the tap was made in the breaker enclosure and I would agree with David that the EGC tap to the enclosure must be full sized based on the feeder OCPD size.

I agree also.

 

[kwired]

In the pictures the tap was made in the breaker enclosure and I would agree with David that the EGC tap to the enclosure must be full sized based on the feeder OCPD size.

That is what I was trying to say in earlier post, David happened to state the same thing in a simpler way - thanks David.

 

[cohosilver]

Outside Taps of Unlimited Length

Outside Taps of Unlimited Length

Here is a scenario, the installation is a 250kW solidly wye grounded generator with an 800A MCB feeding a 400 amp main distribution panel with a 4-conductor 500mcm w/ #2 awg ground ER-TC direct burial cable approximately 200 feet away from the generator. The cable is buried. The panel is not bonded.

As I understand, many times the unlimited tap rule is used on farms or in agricultural areas with long runs.

Per the discussion, it seems that these installations will always require an egc to be the same size as the line conductors. In my case, the egc should be a 1/0awg per T250.122. What is the solution, run an separate external egc along with the cable? There isn't a way the owner is going to pay to have this refed.

Just curious.

 

[iwire]

Per the discussion, it seems that these installations will always require an egc to be the same size as the line conductors. In my case, the egc should be a 1/0awg per T250.122. What is the solution, run an separate external egc along with the cable?

You cannot run the EGC outside the cable due to 300.3(B).

There isn't a way the owner is going to pay to have this refed.

In that case there will always be a violation unless some one adds 400 amp over current protection to the feeder.


(Wouldn't the fix be on the designer / installer and not the owner?)

 

[infinity]

I think that David's point is that 250.148 applies and the connection to the enclosure must be full sized based on the feeder OCPD, even if that results in a EGC tap that is larger than the tap conductors.

IMO the EGC tap isn't even required in the photo. The EMT can serve as the EGC.

 

[don_resqcapt19]

IMO the EGC tap isn't even required in the photo. The EMT can serve as the EGC.

It would be my opinion that 250.148 would require the EGC tap where the circuit conductors have been tapped.

 

[cohosilver]

Outside Taps of Unlimited Length and EGCs

Outside Taps of Unlimited Length and EGCs

It seems the NEC is clear per 250.122(G) Feeder Taps that the EGC needs to be sized based on the sized on the upstream overcurrent device per T250.122. There are some qualifiers, such as this rule only applies if the EGC is of the wire type (as opposed to RMC, or IMC) and, the EGC does not need to be larger than the ungrounded conductors.

In the circumstance I described with the ER-TC cable, it is a project that I have inherited and is a deficiency that will need correcting.

I sincerely appreciate the input you have provided. This forum something that I think is special.

 

[david]

That is what I was trying to say in earlier post, David happened to state the same thing in a simpler way - thanks David.

I always go over to word to type and copy and paste back here. My post was 15 minutes after yours. I din't notice
you had already posted sorry!!

 

[david]

IMO the EGC tap isn't even required in the photo. The EMT can serve as the EGC.

I am of the opinion because of the TAP (Splice) the metal enclosure that encloses that tap has to have an equipment bonding jumper to bond the enclosure. I am saying it has to be based on the equipment ground size run with the feeders passing through the metal tub. I am staying away from the language that it has to be based on the upstream overcorrect protection. In the back of my mind I know that the feeders could have been upsized there by requiring the equipment ground to be up sized the same %. If so then the equipment bonding jumper that provides the fault clearing path for the metal enclosure would have to be the same size as the equipment ground passing through because of the splice (tap) in the enclosure

That is my opinion I may be wrong but I think two rules come into play here and the most restrictive well you know.

 

[infinity]

I am of the opinion because of the TAP (Splice) the metal enclosure that encloses that tap has to have an equipment bonding jumper to bond the enclosure. I am saying it has to be based on the equipment ground size run with the feeders passing through the metal tub. I am staying away from the language that it has to be based on the upstream overcorrect protection. In the back of my mind I know that the feeders could have been upsized there by requiring the equipment ground to be up sized the same %. If so then the equipment bonding jumper that provides the fault clearing path for the metal enclosure would have to be the same size as the equipment ground passing through because of the splice (tap) in the enclosure

That is my opinion I may be wrong but I think two rules come into play here and the most restrictive well you know.

In the case of the tap in the photo the question is are the condcutors actually spliced. Since the tapping device allows the conductors to remain unbroken IMO they are not spliced. A bit of semantics but as far as I know the word splice is not defined by the NEC.

 

[kwired]

It would be my opinion that 250.148 would require the EGC tap where the circuit conductors have been tapped.

I am of the opinion because of the TAP (Splice) the metal enclosure that encloses that tap has to have an equipment bonding jumper to bond the enclosure. I am saying it has to be based on the equipment ground size run with the feeders passing through the metal tub. I am staying away from the language that it has to be based on the upstream overcorrect protection. In the back of my mind I know that the feeders could have been upsized there by requiring the equipment ground to be up sized the same %. If so then the equipment bonding jumper that provides the fault clearing path for the metal enclosure would have to be the same size as the equipment ground passing through because of the splice (tap) in the enclosure

That is my opinion I may be wrong but I think two rules come into play here and the most restrictive well you know.

I agree with both of these posts.

In the case of the tap in the photo the question is are the condcutors actually spliced. Since the tapping device allows the conductors to remain unbroken IMO they are not spliced. A bit of semantics but as far as I know the word splice is not defined by the NEC.

I don't feel it matters if you call it a splice or not. The overcurrent device protecting the feeder is what determines the EGC size for any metallic non current carrying component that may be energized by the feeder. If the tap would leave the enclosure the EGC associated with the tap would not need to be larger than the tap conductors max, the bond to the enclosure containing the tap would still need to be sized to the feeder overcurrent device, because the enclosure contains the feeder.