Proper way to install 2224 Al cable in conduit

[bobinyelm]

I am working in Washington State (Thurson County, using WA L&I State Inspection)

I am wiring my shop to my home panel, and for 100 amp service have settled on 2224 alum cable.

I asked my elec inspector, and he told me that to run the cable, it had to be in conduit from my home panel to my shop panel (nowhere exposed except inside the panels) , and that it could not be in a sheath (like Romex), but had to be bare insulated wires. He said I CAN run Romex inside NMC as long as it was for protection only (below 8ft above floor level I have to "protect" the Romex in conduit, run it below structural members, or put it behind other protection).

That would make it type URD cable as far as I can tell? (Question #1)
(I noticed here on the Forum Type SER cable was recommended for this use, but it is sheathed)

Would 1 1/2" non-metallic conduit be appropriate end-to-end? (Question 2)
I know the cable cannot occupy more than 53% of the conduit cross section)

The elec guy at Home Depot said that he thought Sched 40 conduit was OK above ground, but that I should use Sched 80 PVC conduit below ground.

The past job like this (20+ years ago, same jurisdiction) I basically built the conduit around the cable (assembled the conduit OVER the cable, cementing it as I went. This kept me from having to "pull" the wires through the 100ft run and the bends. But, in a thread on this Forum I just read that this is NOT the proper way it should be done. I should assemble the entire conduit, and then pull the cable through it. The poster said that separate conductors should be pulled individually through the conduit as pulling twisted cable through conduit s difficult (the Home Depot guy confirmed pulling 75ft of 2224 through my proposed run would be VERY difficult due to the proposed bends).

Is there a technical reason I should not run the conduit over the cable , cementing as I go? Is it some kid of "code" that wire has to be "pulled?" If so, I have to ask WHY it matters as long as the conduit is safe inside the conduit?

Any and all comments/suggestions welcome.

Thanks-

 

[Norcal]

The NEC requires that the conduit be installed prior to pulling in the conductors, & SCH 40 PVC is fine for underground use but if subject to physical damage the points where it stubs up through the ground may require the use of SCH 80 PVC, one reason besides the NEC requiring the run to be assembled before pulling the conductors, is that the PVC solvent cement could have detrimental effects on the conductors insulation if slopped on it, if 2" is used it should pull with ease.


URD cannot be used in a structure.

 

[dw1]

I am working in Washington State (Thurson County, using WA L&I State Inspection)

I am wiring my shop to my home panel, and for 100 amp service have settled on 2224 alum cable.

I asked my elec inspector, and he told me that to run the cable, it had to be in conduit from my home panel to my shop panel (nowhere exposed except inside the panels) , and that it could not be in a sheath (like Romex), but had to be bare insulated wires. He said I CAN run Romex inside NMC as long as it was for protection only (below 8ft above floor level I have to "protect" the Romex in conduit, run it below structural members, or put it behind other protection).

That would make it type URD cable as far as I can tell? (Question #1)
(I noticed here on the Forum Type SER cable was recommended for this use, but it is sheathed)

Would 1 1/2" non-metallic conduit be appropriate end-to-end? (Question 2)
I know the cable cannot occupy more than 53% of the conduit cross section)

The elec guy at Home Depot said that he thought Sched 40 conduit was OK above ground, but that I should use Sched 80 PVC conduit below ground.

The past job like this (20+ years ago, same jurisdiction) I basically built the conduit around the cable (assembled the conduit OVER the cable, cementing it as I went. This kept me from having to "pull" the wires through the 100ft run and the bends. But, in a thread on this Forum I just read that this is NOT the proper way it should be done. I should assemble the entire conduit, and then pull the cable through it. The poster said that separate conductors should be pulled individually through the conduit as pulling twisted cable through conduit s difficult (the Home Depot guy confirmed pulling 75ft of 2224 through my proposed run would be VERY difficult due to the proposed bends).

Is there a technical reason I should not run the conduit over the cable , cementing as I go? Is it some kid of "code" that wire has to be "pulled?" If so, I have to ask WHY it matters as long as the conduit is safe inside the conduit?

Any and all comments/suggestions welcome.

Thanks-

Bob, unless the URD is dual rated, it cannot be ran/used indoors, check to make sure yours is, or if you use URD and its not dual/fire rated, you need to switch over to a fire rated wire before entering your structures (Jbox ect)
I would run 2" pvc pipe, just to help on pulling. I would use use Schedule 40, if you need more protection above ground, you can stub up out of the ground with schedule 80. Try to run the pvc in a direct (straight) path to your shop, that would give you 2 -90* bends and easier to pull, you can use an LB fitting for pulling relief also. If your inspector is giving you job specifics on the rest of the wiring to your panel, does your town/county have any addendums to the NEC? Others out your way will chime in here and have more info. A quart of wire pulling lubricant can help also when pulling the wire in the PVC to your shop. Good Luck, don't for get ground rods (I am guessing this is a detached structure)

 

[bobinyelm]

Bob, unless the URD is dual rated, it cannot be ran/used indoors, check to make sure yours is, or if you use URD and its not dual/fire rated, you need to switch over to a fire rated wire before entering your structures (Jbox ect)

Thanks-

So URD has to be fire rated even if contained inside conduit if the conduit passes through the building's wall and into the panel?

So i guess i must make sure the URD is fire rated. The specs in the Home Depot catalog (it is a special order) don't mention a fire rating for any of the wire/cables i can see.

I sure dont want to be splicing 2-2-2-4 cable if i can help it.

 

[dw1]

Look for MHF (Mobile Home Feeder), they have it listed at your HD in Olympia except by the roll. Are there are electrical supply houses around? might even be cheaper?

Norcal was typing faster

 

[theoldwizard1]

The elec guy at Home Depot said that he thought Sched 40 conduit was OK above ground, but that I should use Sched 80 PVC conduit below ground.

I know of no mandatory requirements for using Schedule 80 anywhere. Recommended for underground, sure. Highly recommended where it comes above ground and could be struck by a lawn mower/string trimmer.

Look for MHF (Mobile Home Feeder), they have it listed at your HD in Olympia

MHF is 4 aluminum conductors without a sheath. I believe it is limited to 90A. It can be directky buried, but must be in conduit anywhere it is above ground. Confirm this with your inspector.

2-2-2-4 Aluminum Mobile Home Feeder Cable - $1.17/ft + shipping

If you don't want to run conduit inside, you can install a junction box where the MHF enters and splice it to 2-2-2-4 SER - $1.35/ft.

 

[zmaxmotorsports]

The NEC requires that the conduit be installed prior to pulling in the conductors, & SCH 40 PVC is fine for underground use but if subject to physical damage the points where it stubs up through the ground may require the use of SCH 80 PVC, one reason besides the NEC requiring the run to be assembled before pulling the conductors, is that the PVC solvent cement could have detrimental effects on the conductors insulation if slopped on it, if 2" is used it should pull with ease.


URD cannot be used in a structure.

I'd go with the 2" also.

 

[pattenp]

There are other choices of wire to be used if running conduit from panel to panel. You can make up the four conductors using THHN/THWN or XHHW or RHH/RHW/USE. Of those I'd go with the XHHW if making up the four conductors. The difference is MHF is a ready made four conductor assembly and is direct bury rated. The RHH/RHW/USE is also direct bury rated and that is what MHF is made up of. But if using conduit you don't need to pay the extra for the direct bury rating.

And do use 2" conduit.

 

[bobinyelm]

I know of no mandatory requirements for using Schedule 80 anywhere. Recommended for underground, sure. Highly recommended where it comes above ground and could be struck by a lawn mower/string trimmer.


MHF is 4 aluminum conductors without a sheath. I believe it is limited to 90A. It can be directky buried, but must be in conduit anywhere it is above ground. Confirm this with your inspector.

2-2-2-4 Aluminum Mobile Home Feeder Cable - $1.17/ft + shipping

If you don't want to run conduit inside, you can install a junction box where the MHF enters and splice it to 2-2-2-4 SER - $1.35/ft.

I can do conduit inside since the panels are right on the walls above which the underground runs would both end. Just up and stright into the box.

So URD is not allowed in a structure even inside a conduit but MHF is essentially identical (it's 2-2-2--4 in other words) but CAN be in a wall if in a conduit UNLIKE URD). I cannot direct bury unless I go 36" deep (not practical), so will use 2" conduit.

I guess I can go Sch 40 but can easily use lengths of Sch 80 for the vertical portion as it exits the el to the conduit body (LB) that goes into the wall.

I will call my inspector Monday and run it past him. I am not allowed to ask him for suggestions or for code interpetations-I can only ask yes/no questions and your suggestions allow me to frame my Qs as yes/no.

The rules turn it into kind of a game, but I guess I see the point. Inspection is Pass/Fail, which is like Yes/No. Maybe licensed electricians have more latitude to ask inspectors "advice" questions since they are professionals.

 

[Cmreschke]

If you can't ask him for code interpretations then what the hell is the point in having him? I agree about the design issue but just making you frame a question in yes no answers is rediculas to say the least. Just my opinion.

 

[Norcal]

A inspector cannot tell someone how to do the job, they are there to inspect for code compliance, although where I reside it's just revenue.

 

[Cmreschke]

Yes Norcal I agree up to the part where he can not give an interpretation of the nec.

 

[alfredeneuman]

I know of no mandatory requirements for using Schedule 80 anywhere.

It's in the NEC "352.12 Uses Not Permitted. PVC conduit shall not be used
under the conditions specified in 352.12(A) through (E).

(C) Physical Damage. Where subject to physical damage
unless identified for such use."

The crush resistance rating of Sch 80 is approx double that of Sch 40 and is identified for the use.

 

[bobinyelm]

It's in the NEC "352.12 Uses Not Permitted. PVC conduit shall not be used
under the conditions specified in 352.12(A) through (E).

(C) Physical Damage. Where subject to physical damage
unless identified for such use."

The crush resistance rating of Sch 80 is approx double that of Sch 40 and is identified for the use.

OK-

If I read you right, if conduit is buried, it is subject to crush forces (physical damage), and therefore should be Sch 80?

 

[bobinyelm]

If you can't ask him for code interpretations then what the hell is the point in having him? I agree about the design issue but just making you frame a question in yes no answers is rediculas to say the least. Just my opinion.

If I ask him a question that is yes/no, he quotes a line from the NEC that acts as a clue to my answer. Sometimes if I re-frame the question, he will just read the same line to me over a second time, and then I have to see how that answers my question and take a chance and will see during inspection if I guessed right.

For instance, I asked if a breaker panel can be mounted "inverted," with the main breaker at the bottom. He read a line stating that breakers must operate left/right. If I read him right, if inverting the box allows breakers to still operate left/right, it's OK to invert the box. I used the word "horizontal" for left/right, and he said the code does not say that, and he re-read me "left/right," so I will mount the panel what is (for me) upside down w/ the main breaker at the bottom, and since it still operates left/right I am guessing I will be OK.

Just an example of the guessing game we play.

Hopefully when he inspects the majority of my guesses on code "meaning" will be correct.

 

[bobinyelm]

Yes Norcal I agree up to the part where he can not give an interpretation of the nec.

True, though obviously he will inspect based on his interpretation of the NEC.

Theoretically, the NEC is perfectlyclear, so there is room for only one interpretation (the intended one), so he will have no latitude (an neither will I if I read it CORRECTLY).

In truth, I see situations where licensed electricians have different answers reading the same code, so the NEC isn't perfectly worded I guess, which could mean different inspectors may also have slightly different answers.

 

[alfredeneuman]

OK-

If I read you right, if conduit is buried, it is subject to crush forces (physical damage), and therefore should be Sch 80?

No.

It's not subject to physical damage when buried.
It's subject to damage aboveground.

 

[wyliesdiesels]

I am working in Washington State (Thurson County, using WA L&I State Inspection)

I am wiring my shop to my home panel, and for 100 amp service have settled on 2224 alum cable.

I asked my elec inspector, and he told me that to run the cable, it had to be in conduit from my home panel to my shop panel (nowhere exposed except inside the panels) , and that it could not be in a sheath (like Romex), but had to be bare insulated wires. He said I CAN run Romex inside NMC as long as it was for protection only (below 8ft above floor level I have to "protect" the Romex in conduit, run it below structural members, or put it behind other protection).

That would make it type URD cable as far as I can tell? (Question #1)
(I noticed here on the Forum Type SER cable was recommended for this use, but it is sheathed)

Would 1 1/2" non-metallic conduit be appropriate end-to-end? (Question 2)
I know the cable cannot occupy more than 53% of the conduit cross section)

The elec guy at Home Depot said that he thought Sched 40 conduit was OK above ground, but that I should use Sched 80 PVC conduit below ground.

The past job like this (20+ years ago, same jurisdiction) I basically built the conduit around the cable (assembled the conduit OVER the cable, cementing it as I went. This kept me from having to "pull" the wires through the 100ft run and the bends. But, in a thread on this Forum I just read that this is NOT the proper way it should be done. I should assemble the entire conduit, and then pull the cable through it. The poster said that separate conductors should be pulled individually through the conduit as pulling twisted cable through conduit s difficult (the Home Depot guy confirmed pulling 75ft of 2224 through my proposed run would be VERY difficult due to the proposed bends).

Is there a technical reason I should not run the conduit over the cable , cementing as I go? Is it some kid of "code" that wire has to be "pulled?" If so, I have to ask WHY it matters as long as the conduit is safe inside the conduit?

Any and all comments/suggestions welcome.

Thanks-

If u want 100a, then u must use #1 al as #2 al is limited to 90a in this scenario.

The conduit requirement for the whole run must be a local amendment as there is direct burial rated wire.

URD cannot be inside as said above and SER cannot be ran underground because its not rated for underground wet locations conduit included.

The home depot guy has it backwards....

Thanks-

So URD has to be fire rated even if contained inside conduit if the conduit passes through the building's wall and into the panel?

So i guess i must make sure the URD is fire rated. The specs in the Home Depot catalog (it is a special order) don't mention a fire rating for any of the wire/cables i can see.

I sure dont want to be splicing 2-2-2-4 cable if i can help it.

URD doesnt have a fire rating. U need to check and see if the cable has a RHH/RHW rating. This means it is fire resistant.

And #2 isnt too bad to splice.

If you can't ask him for code interpretations then what the hell is the point in having him? I agree about the design issue but just making you frame a question in yes no answers is ridiculous to say the least. Just my opinion.

It would be a liability issue if he did give interpretations and instructions on how to do the work. They are there solely to say yeah or nay on whether it passes code.

If they say nay then u can ask why. If they give u a reason that goes against known code then u can challenge him as he cant make u do something that goes against code and local amendments.

 

[pattenp]

.............
URD cannot be inside as said above and SER cannot be ran underground because its not rated for wet locations conduit included.

I don't mean to nitpick, but SER is rated for wet locations, just not below ground.

 

[dw1]

So URD is not allowed in a structure even inside a conduit but MHF is essentially identical (it's 2-2-2--4 in other words) but CAN be in a wall if in a conduit UNLIKE URD). I cannot direct bury unless I go 36" deep (not practical), so will use 2" conduit.

I guess I can go Sch 40 but can easily use lengths of Sch 80 for the vertical portion as it exits the el to the conduit body (LB) that goes into the wall.

I will call my inspector Monday and run it past him. I am not allowed to ask him for suggestions or for code interpetations-I can only ask yes/no questions and your suggestions allow me to frame my Qs as yes/no.

The rules turn it into kind of a game, but I guess I see the point. Inspection is Pass/Fail, which is like Yes/No. Maybe licensed electricians have more latitude to ask inspectors "advice" questions since they are professionals.

300.5 of the NEC. Not sure where you got your 36" burial depth, direct burial cables/conductors is 24" and in pvc is 18"

 

[pattenp]

bobinyelm, the insulation type determines if the wire can be used inside or just outside the structure. URD usually only carries a USE-2 insulation rating which does not have fire retardant in the insulation. Insulation types such as RHH/RHW, THHN/THWN, and XHHW do have fire retardant in the insulation so they can be installed inside the structure. NEC Table 310.104(A) has the wire insulation types listed.

 

[wyliesdiesels]

I don't mean to nitpick, but SER is rated for wet locations, just not below ground.

Yeah i forgot a word.

Thx

 

[bobinyelm]

300.5 of the NEC. Not sure where you got your 36" burial depth, direct burial cables/conductors is 24" and in pvc is 18"

Yes, sorry.

I cannot go down 24" due to crossing a Nat Gas line at 24" so will be using conduit at 18" to remove this hazard. Even though I had the lines marked, I don't want to chance hitting my plastic NatGas line even w/ a pick or mattock.

The excavator who installed my Nat Gas conduit said he couldn't remember the exact burial depth of the gas (there was back filling of the area afterward for landscaping and controlling runoff), but it was 24-36" . That's where I "got" my 36" figure I guess.

 

[bobinyelm]

If you can't ask him for code interpretations then what the hell is the point in having him?

He was very open that his function was to inspect, and not to instruct, but he said I could ask properly framed questions, and is available 30min a day for such questions before he starts his inspection rounds, but that I should not abuse the courtesy (which is why I am asking basic questions here I don't understand before resorting to asking the inspector).

I get the idea that in most places, authorities would just prefer people hire professionals to do such jobs, which I get, but I was told my job would likely cost $4500 plus the burial portion since I have so many circuits, and much is above 8ft in height, so it's an economic thing for me (plus I enjoy doing the work as long as I understand the rules).

I suspect dealing with 10% DIYers probably creates 30% of the workload inspectors do, since pros know the Code, and rarely have to do anything over.

I looked at the ratings of the cable used for my main house circuit (I can see the portion that runs to the main breaker inside the panel) and it's type USE RHW-2, so I can't go far wrong duplicating these ratings I guess. It is 4/0 Aluminum in a conduit from the meter box mounted on my pole at the street, which is 150ft from my main panel.

As far as the rating of #2 AL, yes, direct burial is 100a, but if it's in a conduit I understand am limited to 90a. My shop panel is a 100a box w/ a 100a main breaker, but the breaker in my house box that will feed it will be limited to 90a. The inspector said I could even use a 200a panel and main breaker in the shop as long as the feed breaker is properly rated for the "weakest link" in this case the #2 AL wiring.

 

[Norcal]

He was very open that his function was to inspect, and not to instruct, but he said I could ask properly framed questions, and is available 30min a day for such questions before he starts his inspection rounds, but that I should not abuse the courtesy (which is why I am asking basic questions here I don't understand before resorting to asking the inspector).

I get the idea that in most places, authorities would just prefer people hire professionals to do such jobs, which I get, but I was told my job would likely cost $4500 plus the burial portion since I have so many circuits, and much is above 8ft in height, so it's an economic thing for me (plus I enjoy doing the work as long as I understand the rules).

I suspect dealing with 10% DIYers probably creates 30% of the workload inspectors do, since pros know the Code, and rarely have to do anything over.

I looked at the ratings of the cable used for my main house circuit (I can see the portion that runs to the main breaker inside the panel) and it's type USE RHW-2, so I can't go far wrong duplicating these ratings I guess. It is 4/0 Aluminum in a conduit from the meter box mounted on my pole at the street, which is 150ft from my main panel.

As far as the rating of #2 AL, yes, direct burial is 100a, but if it's in a conduit I understand am limited to 90a. My shop panel is a 100a box w/ a 100a main breaker, but the breaker in my house box that will feed it will be limited to 90a. The inspector said I could even use a 200a panel and main breaker in the shop as long as the feed breaker is properly rated for the "weakest link" in this case the #2 AL wiring.

It's still 90A buried or not.

 

[wyliesdiesels]

He was very open that his function was to inspect, and not to instruct, but he said I could ask properly framed questions, and is available 30min a day for such questions before he starts his inspection rounds, but that I should not abuse the courtesy (which is why I am asking basic questions here I don't understand before resorting to asking the inspector).

I get the idea that in most places, authorities would just prefer people hire professionals to do such jobs, which I get, but I was told my job would likely cost $4500 plus the burial portion since I have so many circuits, and much is above 8ft in height, so it's an economic thing for me (plus I enjoy doing the work as long as I understand the rules).

I suspect dealing with 10% DIYers probably creates 30% of the workload inspectors do, since pros know the Code, and rarely have to do anything over.

I looked at the ratings of the cable used for my main house circuit (I can see the portion that runs to the main breaker inside the panel) and it's type USE RHW-2, so I can't go far wrong duplicating these ratings I guess. It is 4/0 Aluminum in a conduit from the meter box mounted on my pole at the street, which is 150ft from my main panel.

As far as the rating of #2 AL, yes, direct burial is 100a, but if it's in a conduit I understand am limited to 90a. My shop panel is a 100a box w/ a 100a main breaker, but the breaker in my house box that will feed it will be limited to 90a. The inspector said I could even use a 200a panel and main breaker in the shop as long as the feed breaker is properly rated for the "weakest link" in this case the #2 AL wiring.

Where did u get this?

It isnt correct.

Direct burying wire doesnt change the ampacity. #2 al feeding a non dwelling building has an ampacity of 90a (table 310.15(b)(16) 75* column. PERIOD!

The only exception allowing 100a amapcity on #2 al is IF the wire feeds the entire load of a dwelling....

 

[bobinyelm]

It's still 90A buried or not.

Interesting.

I found several references that if supplying a "whole dwelling" it was rated at 100a because they said it was extremely unlikely that the 100a would be approached.

I must have read 100+ threads on various forums, so don't ask me for all the references (though I'll look to see if I can find some), but the writers quoted some code or other. They said that since a shop is not a dwelling, it probably cannot be rated at 100a (90deg), but rather at its 90a 75deg rating.

I am not arguing w/ you, since I don't have any basis other than what I read, which could be 100% wrong. I just offer it because that's where I saw 100a. Some said that heat dissipation in direct burial allows the wire to stay cooler than if run in air in conduit. Again, just what I read. Not saying they were right.

This is very confusing for a neophyte, to say the least! #2 below showed your user name (Norcal) and you (presumably) said in 2008 code #2 is only good for 75 amps (see below).

Found these:
1) pattenp
08-30-2012, 08:22 AM
For a feeder the #2 Al is good to 90A not 100A. #2 Al used as service entrance carrying the whole load to a dwelling can be used at 100A. That chart is for 3 wire service entrance. You are doing a 4 wire branch/feeder circuit, which is a different chart/table. It's a NEC thing. If you can be happy with 90A use Mobile Home Feeder 2-2-2-4 or 2-2-4-6. at http://www.garagejournal.com/forum/archive/index.php/t-163889.html

2) From another thread this says 2-2-2-4 is only good to 75a
(Norcal
05-21-2011, 05:27 PM
2224 ser isn't legal for 100 amp subpanel if on 2008 code or newer. Its only good for 75 amps) at thread:
http://www.garagejournal.com/forum/archive/index.php/t-103100.html

3) This is another confusing post:
04-07-11, 11:00 AM #4 JimElectric JimElectric is offline
Member
Join Date
Dec 2010
State
WV
Posts
243
2-2-2-4 SER aluminum is rated for "residential dwellings" for 100 amp service use, so Lowes and even the company I work for as well as local competitors sell that cable. However, I chose to run # 2 copper on mine. Of course that was well before copper went to $4.30 a lb!
Local codes may differ of course.
04-07-11, 11:10 AM #5 ibpooks ibpooks is offline
Forum Topic Moderator
Join Date
Feb 2005
State
MI
Posts
9,777
Quote Originally Posted by JimElectric View Post
2-2-2-4 SER aluminum is rated for "residential dwellings" for 100 amp service
But only when it's the main panel for the dwelling, and the service is entirely or mostly outdoors. For subpanels and other uses the 310.16 table must be used which provides for either 75A or 90A depending on specifics of the installation. at http://www.garagejournal.com/forum/showthread.php?t=291637

 

[mm08822]

Interesting.

I found several references that if supplying a "whole dwelling" it was rated at 100a because they said it was extremely unlikely that the 100a would be approached.

I must have read 100+ threads on various forums, so don't ask me for all the references (though I'll look to see if I can find some), but the writers quoted some code or other. They said that since a shop is not a dwelling, it probably cannot be rated at 100a (90deg), but rather at its 90a 75deg rating.

I am not arguing w/ you, since I don't have any basis other than what I read, which could be 100% wrong. I just offer it because that's where I saw 100a. Some said that heat dissipation in direct burial allows the wire to stay cooler than if run in air in conduit. Again, just what I read. Not saying they were right.

This is very confusing for a neophyte, to say the least! #2 below showed your user name (Norcal) and you (presumably) said in 2008 code #2 is only good for 75 amps (see below).

Found these:
1) pattenp
08-30-2012, 08:22 AM
For a feeder the #2 Al is good to 90A not 100A. #2 Al used as service entrance carrying the whole load to a dwelling can be used at 100A. That chart is for 3 wire service entrance. You are doing a 4 wire branch/feeder circuit, which is a different chart/table. It's a NEC thing. If you can be happy with 90A use Mobile Home Feeder 2-2-2-4 or 2-2-4-6. at http://www.garagejournal.com/forum/archive/index.php/t-163889.html

2) From another thread this says 2-2-2-4 is only good to 75a
(Norcal
05-21-2011, 05:27 PM
2224 ser isn't legal for 100 amp subpanel if on 2008 code or newer. Its only good for 75 amps) at thread:
http://www.garagejournal.com/forum/archive/index.php/t-103100.html

3) This is another confusing post:
04-07-11, 11:00 AM #4 JimElectric JimElectric is offline
Member
Join Date
Dec 2010
State
WV
Posts
243
2-2-2-4 SER aluminum is rated for "residential dwellings" for 100 amp service use, so Lowes and even the company I work for as well as local competitors sell that cable. However, I chose to run # 2 copper on mine. Of course that was well before copper went to $4.30 a lb!
Local codes may differ of course.
04-07-11, 11:10 AM #5 ibpooks ibpooks is offline
Forum Topic Moderator
Join Date
Feb 2005
State
MI
Posts
9,777
Quote Originally Posted by JimElectric View Post
2-2-2-4 SER aluminum is rated for "residential dwellings" for 100 amp service
But only when it's the main panel for the dwelling, and the service is entirely or mostly outdoors. For subpanels and other uses the 310.16 table must be used which provides for either 75A or 90A depending on specifics of the installation. at http://www.garagejournal.com/forum/showthread.php?t=291637

You answered your own question without realizing it. The service entrance conductors feeding a residential dwelling have a different rating (actually an exception) that permits a higher ampacity than the same conductors used as a feeder.

The line to your shop is considered a feeder and not service entrance conductors.

 

[bobinyelm]

You answered your own question without realizing it. The service entrance conductors feeding a residential dwelling have a different rating (actually an exception) that permits a higher ampacity than the same conductors used as a feeder.

The line to your shop is considered a feeder and not service entrance conductors.

Which is exactly why I came here asking questions to try to understand what on the face of it seemed confusing.

Slowly, I am filling in the blank spots so I can do the job to satisfy the Code and the inspector.

Bottom line, I guess #2 can be rated at 75, 90, or 100a depending upon the application.

Just to be sure, in MY application (a "feeder") it can be breakered at 90a in my main panel, but 100a in my shop panel (which is the main breaker it was supplied with). (?)

BTW, the ground wire in the 2-2-2-4 MHF USE-2, RWH-2 cable is #4. What gauge ground wire is minimum from my shop panel to the 2 6ft ground rods I need to place at the shop?

My understanding is that I only need ONE grounding wire to BOTH rods. Again, is this true?

Does the ground wire to the rods need to be stranded? One Home Depot electrical dept person said it could be solid, but didn't know what gauge, though my house uses stranded ground (to ONE ground rod, a piece of rebar driven/cast into through the foundation wall of my garage below the main panel).

Thanks-

 

[dw1]

Which is exactly why I came here asking questions to try to understand what on the face of it seemed confusing.

Slowly, I am filling in the blank spots so I can do the job to satisfy the Code and the inspector.

Bottom line, I guess #2 can be rated at 75, 90, or 100a depending upon the application.

Just to be sure, in MY application (a "feeder") it can be breakered at 90a in my main panel, but 100a in my shop panel (which is the main breaker it was supplied with). (?)

BTW, the ground wire in the 2-2-2-4 MHF USE-2, RWH-2 cable is #4. What gauge ground wire is minimum from my shop panel to the 2 6ft ground rods I need to place at the shop?

My understanding is that I only need ONE grounding wire to BOTH rods. Again, is this true?

Does the ground wire to the rods need to be stranded? One Home Depot electrical dept person said it could be solid, but didn't know what gauge, though my house uses stranded ground (to ONE ground rod, a piece of rebar driven/cast into through the foundation wall of my garage below the main panel).

Thanks-

One wire from your panel to your ground rods (Ground rods spaced at least 6' a part) you can use Copper # 6 or # 4 aluminum- stranded or solid, I always use # 6 copper, green, stranded, its what readily available at supply house. (8' grounds rods)

 

[pattenp]

The #2 Al at 75 deg. C is 90A, at 60 deg. C it's 75A. The type of wire and it's application determines the amp rating that can be used. It's not a one size fits all situation. From my experience the most common wire used for the grounding electrode conductor is bare solid #6 copper.

Edit: Bottom line per the NEC #2 MHF can be used at 75 deg. C for 90A. You can take that to the bank unless you have some local code that doesn't allow it or an inspector that say's otherwise and doesn't know better.

 

[markushofer27]

Lay out your wire next t the trench and slide on on piece of pipe at a time and glue,we 1000s of feet a year that way.

 

[Norcal]

Lay out your wire next t the trench and slide on on piece of pipe at a time and glue,we 1000s of feet a year that way.

And it does not comply with code in any way, shape, or form.

 

[pattenp]

Lay out your wire next t the trench and slide on on piece of pipe at a time and glue,we 1000s of feet a year that way.

I wouldn't recommend doing it that way. If the glues drips on the wire insulation it can damage the insulation and also glue the wire in place. The biggest thing is as Norcal pointed out it's against NEC.

 

[markushofer27]

And it does not comply with code in any way, shape, or form.

Ream the ends of the pipe before u slide em on,if sliding pipe on the wire, verses pulling it in after makes u lose sleep at night then pull afterwards.

 

[pattenp]

Ream the ends of the pipe before u slide em on,if sliding pipe on the wire, verses pulling it in after makes u lose sleep at night then pull afterwards.

So what other non code compliant install methods do you practice that don't make you lose sleep at night?

 

[markushofer27]

Just because it's against the nec doesn't make it unsafe, just because it's to code
doesn'tmake it safe.

 

[markushofer27]

Then again 100 ft with couple 90s with 1 1/2 pvc is an easy pull with 2 people.

 

[bobinyelm]

Lay out your wire next t the trench and slide on on piece of pipe at a time and glue,we 1000s of feet a year that way.

To be honest, the state electrical inspector who oversaw my first job involving PVC conduit 20+ years ago actually recommended doing it this way (until I just learned here, I had no idea code requires pulling wire through completed PVC conduit).

He told me he'd seen much more damage to insulation caused by careless pulling than by the assembly over the cable over the years, but never mentioned that it was unacceptable by code, so I thought it was OK until it was pointed out otherwise here

The inspector advised me to apply cement to the male pipe (but not to the very end so cement wouldn't seep onto the wire) by after inserting the reamed/chamfered male end into the bell about 1/4" first, applying glue around the conduit, then push and rotate the pipe until it bottomed (used a sharpie to approximately mark the insertion depth on the pipe). Made sense to me at the time as a newbie not knowing better.

That inspector kind of took me under his wing, liked instructing, and enjoyed getting professional results from his layman charges. I am sure he is long retired, or has passed by now, given his age then.

Goes to show even the best can be very flawed people.

 

[crook038]

I recently installed a service to my garage very similar to what you are doing,
http://www.garagejournal.com/forum/showthread.php?t=348336&highlight=crook038

I used SER inside the dwelling and transitioned to single conductor to run thru the underground conduit. I was able to pull the wire thru the 1-1/2" conduit with minimal effort. I had to have the trench with conduit inspected prior to installing the wire. Hope this helps.

Sean