running electrical line to garage

[SL6RAM]

I have one more question for the group in regards to my 30x45' garage I hope to build. The garage would be about 50 yards from the house and main electrical panel. I would like to price out an electrical line to the garage. I would like to run a 50 amp sub panel in the garage. I see they sell both a direct burial cable and a regular cable that would be put in a conduit. What is better? How would I pull the heavy wire through the conduit, 50 feet? Should I use copper or aluminum? Would 6 ga be enough or would I have to run 4 ga because of the distance?
thank you, this group has been very helpful.

 

[mrb]

dont put a cable in conduit. Put individual conductors in conduit or use direct burial cable. Conduit is better and the cost increase is negligible. Unless you are somewhere aluminum would not be a wise choice (next to the ocean), use aluminum. (another con for direct burial cable, if you use aluminum direct bury and nick the insulation the aluminum will corrode and burn through in a few years)

 

[Aceman]

I wouldn't recommend direct burial cable. Pvc is cheap. I'm replacing a 1000' run right now with pvc because the direct buried aluminum failed. It's not the first time and it certainly won't be the last...

 

[PassnThru]

dont put a cable in conduit. Put individual conductors in conduit or use direct burial cable. Conduit is better and the cost increase is negligible. Unless you are somewhere aluminum would not be a wise choice (next to the ocean), use aluminum. (another con for direct burial cable, if you use aluminum direct bury and nick the insulation the aluminum will corrode and burn through in a few years)

I'm not sure why you wouldn't put cable in conduit? Is it just a cost thing? I do have cable running through conduit to my garage and I did have an electrician help me with the wiring. He didn't seem to have any problem with it. And the aluminum wire - I thought aluminum wire was something to run away from. Again, a cost thing? I'm not challenging you and saying that you are wrong - I'm no electrician - but I'm curious about the points you made.
To the original poster - why just a 50 AMP panel. If you are doing this new then why not go ahead and run a 100 AMP panel? Is it because of the distance and the resulting larger wire size? I would think seriously about overdoing it now - it will be a lot harder (and expensive) to add capacity later than to put it in now.

 

[mrb]

I'm not sure why you wouldn't put cable in conduit? Is it just a cost thing? I do have cable running through conduit to my garage and I did have an electrician help me with the wiring. He didn't seem to have any problem with it. And the aluminum wire - I thought aluminum wire was something to run away from. Again, a cost thing? I'm not challenging you and saying that you are wrong - I'm no electrician - but I'm curious about the points you made.
To the original poster - why just a 50 AMP panel. If you are doing this new then why not go ahead and run a 100 AMP panel? Is it because of the distance and the resulting larger wire size? I would think seriously about overdoing it now - it will be a lot harder (and expensive) to add capacity later than to put it in now.

cable in conduit:
-depending on the type of cable and size of the conduit you could have fill issues
-its a huge pain to pull vs seperate conductors
-most of the common larger cables (SER,etc) cant go underground even in conduit yet people think its ok if its in conduit.
-there is no benefit to doing it.

aluminum:
i think you are confusing 12 and 10ga aluminum building wire of the 70s from the modern day aluminum conductors and cables. Aluminum is more common than copper in the larger sizes and is much, much more cost effective.

 

[dugger10]

Price #2 Al triplex underground wire, also 1/0 Al triplex. Use 2 inch PVC, its cheap. Utilities run all al. underground wire, including service's to house's. I priced #2 triplex from an electrician friend at 85 cents a foot, retail is probably 1.25 or so a foot. Either size will push through 2 in. pretty easy, one trick is to cut a plastic coke bottle in a wide strip and tape over the end. This will help slide the cable through. Also use soap. lowes and home depot sell wire pulling soap, just pour into conduit where the wire goes in, will make it slide much easier. Another method is run some rope throught the conduit as you glue togather. The neutral wire will be smaller than the hot legs, at the end you attach the rope to the wire cut the hot legs back about 2 foot and tape them down. Tie a loop in your rope and loop the neutral through the rope's loop and tape it very well back to itself, you will need to push the wire in a small lop to fit in the conduit. Have someone pull the rope and someone push the wire, work in sequence and apply additional soap as you go. Should pull pretty easy unless you have several 90's, use sweeping 90's not the short ones. Look for some inhibetor, its a grease like stuff made for alumium wire. Dip or rub some on the ends of the wire and inside the lug connections before inserting and tighten the lugs in the breaker box's at both ends. Most likely the breaker box's you buy with accept al. wire, the inhibitor will aid in connection for al. wire. By using #2 or 1/0 you can easily use a 100 amp service, due to the increase in wire size. The typical all electric house about 2000 square ft is served by a 1/0 al. service. Its really not hard, if your rop brekas you can always **** a strring through with a shop vac and pull another rope through, they do make 100 ft fish tapes that would work too. Sorry so long but I wanted to give details, hope this helps.

 

[mrb]

dugger:
subpanel needs 4 wires, not 3 (in 2008 code, earlier codes if metallic path exists between structures, best practice to install 4 wires regardless)

the triplex cable used for overhead services by utilities is not a listed wire type and cannot be used except on the utility side of the meter. (if the wire is XHHW or another listed type then it would be ok)

#2 AL is not good for 100 amps.

The poco's service drop wire size in the air is much smaller than what is required for anything on the customer side of the meter.

 

[PassnThru]

cable in conduit:
-depending on the type of cable and size of the conduit you could have fill issues
-its a huge pain to pull vs seperate conductors
-most of the common larger cables (SER,etc) cant go underground even in conduit yet people think its ok if its in conduit.
-there is no benefit to doing it.

aluminum:
i think you are confusing 12 and 10ga aluminum building wire of the 70s from the modern day aluminum conductors and cables. Aluminum is more common than copper in the larger sizes and is much, much more cost effective.

-I did size my conduit for the cable so no issue there.
-I'll agree that it is harder to pull cable than separate conductors but with a little soap we didn't have a problem.
-I was not aware that there was any cable that you could not put underground as long as it was in conduit - hopefully my cable is OK.
-As to the benefit, right or wrong I thought it would be better because of one extra layer of protection. No conduit means no protection for the cable other than the insulation. Conduit with cable would seem to offer the most protection to me. I do understand that the protection that the cable wrapper offers is negligible but it does exist.

As for the aluminum, I was thinking after the post that when my neighbors lost a phase a few years ago that the power company ran a new cable and it was aluminum. You were right that I was thinking of the in house wiring - I can see where aluminum would not be an issue with the connections in each box being very secure lugs.
Thanks for the clarifications.

 

[mrb]

-I was not aware that there was any cable that you could not put underground as long as it was in conduit - hopefully my cable is OK.

What type of cable did you use? It would have to be UF or otherwise listed for wet location.

 

[PassnThru]

I have some left over in the garage - it was about 7 years ago so I don't remember exactly. I can check it out tomorrow. I had a guy come over that does electrical on the side. His day job was wiring new construction on schools. I don't think he steered me wrong. He knew the situation and went with me to buy the wire so I think I'm good.

 

[walrus]

My father direct buried a piece of SE to his garage in 1978, its still there and working. Its as wrong as you can get yet it still works I keep waiting for the bare neutral to rot away but it hasn't yet

 

[Charles (in GA)]

My father direct buried a piece of SE to his garage in 1978, its still there and working. Its as wrong as you can get yet it still works I keep waiting for the bare neutral to rot away but it hasn't yet

This falls in the same category as the PVC compressed air pipe. Persons on here, and I have a neighbor, all say, "I've had it for years with no problems, so there cannot be an issue with it"............ Yea, right.

Like you said, that bare neutral wrapped around the other wires in that thin "snakeskin" jacket will fail someday.

Charles

 

[Norcal]

This falls in the same category as the PVC compressed air pipe. Persons on here, and I have a neighbor, all say, "I've had it for years with no problems, so there cannot be an issue with it"............ Yea, right.

Like you said, that bare neutral wrapped around the other wires in that thin "snakeskin" jacket will fail someday.

Charles

If AL it's real risky to lose the neutral as bare aluminum is prone to turning into a toothpaste like substance underground, same thing happens if insulation is damaged on buried AL cables too...

 

[dugger10]

mrb:
Certinaly a 4 wire service would be code and better. I happen to work for a large poco's and have for 30 years. Also was a liscens electrician for several years as well. Most overhead service serving all electric homes are 2/3 al. conductors, we can get away with this because its overhead and heat is dissapathed(sp) by the outside air. By using # 2 al. underground will limit its current carrying capabilities, but on a shop its plenty unless you plan to serve a much larger load than SL6RAM suggested. Because its 50 yards away thier will be some voltage drop. The larger the wire the less the drop. I do believe #2 al. will carry 100 amps even in an underground application, I would want to verify to be sure, copper would be much better but I'm sure you know its much more expensive. He can achieve an isolate ground by installing a ground rod at the shop and connecting the isolated ground block with a short piece of #6 copper. After all thats what all power co. require at the meter base and they run only a 3 wire service for single residential customers. Its safe to run a three wire service to the shop, better to run a four wire as code suggest. Some say installing undergound type cable without conduit is fine and they have a good shot of never having any problems. I would never think of not using conduit, why take the chance. No home owner I now has the equipment to locate an underground fault and most electricians don't either. Conduit also protects unsuspecting people that are digging fence post. Its just too cheap and will save money if a problem does occur. As mention earlier, any nick in the insulation will result in a fault. A rock falling in during backfill can cause a nick that may take a couple years or more to develop, not worth the risk in MHO.
I really would worry about running non-direct bury wire in conduit, I would however make sure my conduit was good. By that I mean water tight, shouldn't be a problem with PVC. Its done all the time and done correctly you will never have a problem. Anyways guys this is just my humble thoughts, been doing this a long time on both sides of the meter. More than one way to skin a cat or wire a building. Good luck

 

[mrb]

dugger:
The power companies dont work under the NEC and are able to get away with greatly reduced wire sizes, and use different wire types.

#2 AL is only good for 90 amps per NEC

Biggest problem with triplex is 98% of it is not of a listed wire type and cannot be used in an installation which is governed by the NEC.

As far as 3 wires vs 4, the only time it would be ok to run 3 wire (the OP is in CT which is still under 2005 NEC. In 2008 its 4 wires no matter what) is if there were no metallic paths between the house and shop. No water, no telephone, no cable tv, nothing. Problem is, do it with 3 wires now, install cable tv later, and you will have current flowing on the shield of the cable tv line.

Where you say "He can achieve an isolate ground by installing a ground rod at the shop and connecting the isolated ground block with a short piece of #6 copper. After all thats what all power co. require at the meter base and they run only a 3 wire service for single residential customers." this is wrong and dangerous. With 4 wire to the shop he still needs ground rods, and bond any water pipe. The issue of 3 wire vs 4 wire has to do with fault currents and such, not so much a ground rod. This is entirely different than between the pole and meter.

Bottom line is there should never be a 3 wire service to the shop. Always 4 wire. Pull a permit and get it inspected.

 

[Norcal]

A ground rod has absolutely nothing w/ clearing faults, a proper grounding path back to the source is what is required ( The source is the transformer) Relying on a ground rod to clear a fault means it will not clear, resulting in a illegal & dangerous situation .


BTW ,2 ground rods are required unless you can prove 25 Ohms of resistance or less & unless you have a few thousand bucks sitting around to buy the required testing instrument, a second rod is more cost effective.

 

[walrus]

This falls in the same category as the PVC compressed air pipe. Persons on here, and I have a neighbor, all say, "I've had it for years with no problems, so there cannot be an issue with it"............ Yea, right.

Like you said, that bare neutral wrapped around the other wires in that thin "snakeskin" jacket will fail someday.

Charles

There's an issue with it, it doesn't meet code. The garage isn't being used but it definitely needs to be replaced. I was in it the other day but haven't used more than the lights in years. Probably should shut the main off.

 

[dugger10]

Guess we'll have to agree to dissagree on some issues mrb. Good luck with the biuld SRL6RAM.

 

[burtonbl]

I have to respectfully disagree.
This can be a huge debate whether 310.15(B)(6) can be used for all feeders. MANY Areas DO allow it. Mine most certainly does.
It becomes semantics and word play as to what allows and what denies it. The words "main feeder" and "last overcurrent device" are two of the most debated phrases.

That said, I DO use #2al for 100 amp feeders (to sub-panels) ALL the time. This is absolutely legal and common in my area.

 

[MrMark]

A ground rod has absolutely nothing w/ clearing faults, a proper grounding path back to the source is what is required ( The source is the transformer) Relying on a ground rod to clear a fault means it will not clear, resulting in a illegal & dangerous situation .


BTW ,2 ground rods are required unless you can prove 25 Ohms of resistance or less & unless you have a few thousand bucks sitting around to buy the required testing instrument, a second rod is more cost effective.

This is all true and since you seem rather knowledgeable about clearing faults and electricity returning to its source, not the ground, as so many people mistakenly think, can you tell me where lightning current goes?

Where is its source? Where does the generated current flow to in order to complete the loop? Does lightning not follow the normal rules of current flowing back to its source?

Why do so many people seem to think current flows to ground?

 

[MrMark]

I have to respectfully disagree.
This can be a huge debate whether 310.15(B)(6) can be used for all feeders. MANY Areas DO allow it. Mine most certainly does.
It becomes semantics and word play as to what allows and what denies it. The words "main feeder" and "last overcurrent device" are two of the most debated phrases.

That said, I DO use #2al for 100 amp feeders (to sub-panels) ALL the time. This is absolutely legal and common in my area.

There is no debate.

The 2008 code makes it clear that the table 310.15(B)(6) applies only to conductors carrying 100 percent of the dwelling unit's diversified load. Subpanel feeders that don't carry the whole load for the dwelling unit don't make the cut. Only the service entrance conductors and main feeders supplying 100 percent of the load to the dwelling unit qualify for this table.

#2 aluminum is only rated for 90 amps with 75 degree termination devices. You and your area are not compling with the NEC.

 

[burtonbl]

There is no debate.

The 2008 code makes it clear that the table 310.15(B)(6) applies only to conductors carrying 100 percent of the dwelling unit's diversified load. Subpanel feeders that don't carry the whole load for the dwelling unit don't make the cut. Only the service entrance conductors and main feeders supplying 100 percent of the load to the dwelling unit qualify for this table.

#2 aluminum is only rated for 90 amps with 75 degree termination devices. You and your area are not compling with the NEC.

We are not talking about Dwelling units main feeder. We are talling about the subpanel feeders.
I am a master electrician in 5 states for almost 18 years now as well as an NFPA 72 Instructor at the Local IBEW NJATC School.
This is a non issue in the north east and every inspector in any town . blesses this all of the time with subpanels. Subpanels are not carrying 100% of the dwellings diversifed load :cheers:

 

[MrMark]

We are not talking about Dwelling units main feeder. We are talling about the subpanel feeders.
I am a master electrician in 5 states for almost 18 years now as well as an NFPA 72 Instructor at the Local IBEW NJATC School.
This is a non issue in the north east and every inspector in any town . blesses this all of the time with subpanels. Subpanels are not carrying 100% of the dwellings diversifed load :cheers:

It doesn't matter one whit to me how long you have been doing this or whether it is allowed in the North East. I am telling you that it is an NEC violation and I can cite and quote the 2008 NEC to prove it, as I have already done. It may have been a subject of debate prior to 2008, but not anymore.

I know guys who have been doing the same thing wrong their whole life. Some never learn. It is mostly a male ego thing. Why don't you look it up in the 2008 code and show me I'm wrong rather than relying on the old fall back of "I'm a master" and all that. I've never met a true master that had to tell anybody he was a master to gain credibility.

 

[MrMark]

I'm surprised the electicians on here that are well-schooled don't back me up on this. It's not that controversial.

 

[JBurgess]

The portion underlined was added in 2008.

310.15(B)

(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
and Feeders. For individual dwelling units of one-family,
two-family, and multifamily dwellings, conductors,
as listed in Table 310.15(B)(6), shall be permitted as
120/240-volt, 3-wire, single-phase service-entrance conductors,
service-lateral conductors, and feeder conductors
that serve as the main power feeder to each dwelling unit
and are installed in raceway or cable with or without an
equipment grounding conductor. For 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. The feeder conductors
to a dwelling unit shall not be required to have an allowable
ampacity rating greater than their service-entrance conductors.
The grounded conductor shall be permitted to be
smaller than the ungrounded conductors, provided the requirements
of 215.2, 220.61, and 230.42 are met.

 

[MrMark]

Thank you, JBurgess

 

[Norcal]

The portion underlined was added in 2008.

310.15(B)

(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
and Feeders. For individual dwelling units of one-family,
two-family, and multifamily dwellings, conductors,
as listed in Table 310.15(B)(6), shall be permitted as
120/240-volt, 3-wire, single-phase service-entrance conductors,
service-lateral conductors, and feeder conductors
that serve as the main power feeder to each dwelling unit
and are installed in raceway or cable with or without an
equipment grounding conductor. For 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. The feeder conductors
to a dwelling unit shall not be required to have an allowable
ampacity rating greater than their service-entrance conductors.
The grounded conductor shall be permitted to be
smaller than the ungrounded conductors, provided the requirements
of 215.2, 220.61, and 230.42 are met.

That section is quite clear, just some inspectors & electricians choose to ignore it.

A number of "electricians" do not even own a copy of the/a NEC.

 

[MrMark]

That section is quite clear, just some inspectors & electricians choose to ignore it.

A number of "electricians" do not even own a copy of the/a NEC.

Even some master electricians who teach at the Unions and whole areas of the country, apparently.

 

[burtonbl]

Even some master electricians who teach at the Unions and whole areas of the country, apparently.

Whatever

I bet you are one of those code quoting Snobs
Who could not think ' on his feet to save his life :cheers:


Met plenty like you



Figures your from Ca
Probably drive a Prius too

YOU drew first blood by the insult above



Never mind just read your profile
Attorney

Now that explains EVERYTHING

 

[MrMark]

Whatever

I bet you are one of those code quoting Snobs
Who could not think ' on his feet to save his life :cheers:


Met plenty like you



Figures your from Ca
Probably drive a Prius too

YOU drew first blood by the insult above



Never mind just read your profile
Attorney

Now that explains EVERYTHING

That's pretty funny stuff. I have to give you credit for that. Especially the Prius part. There are a lot of them around here. I never understood it personally.

 

[wfopete]

Well, the whole issues centers around a common screw up when using the NEC to figure out your wire size. Here's the bottom line: 99% of the wire you buy at the store is rated at 90 degrees centigrade. However for some stupid reason, the lugs in all panels are only rated for 75 degrees. The NEC lists ampacity of wire for both 90 and 75 degrees, and you have to go with the 75 degree column. A lot of people see the 90 degree column and it's slightly higher ampacities and use that for their load calculations, and they're wrong.

MrMark is right, #2 aluminum is NOT good for 100amps. The "master electrician in 5 states" is making a fool of himself, and an IBEW instructor who (a) is ignorant of the NEC and (b) can't think of a better come-back than "you drive a prius" kind of scares me.

 

[Norcal]

Well, the whole issues centers around a common screw up when using the NEC to figure out your wire size. Here's the bottom line: 99% of the wire you buy at the store is rated at 90 degrees centigrade. However for some stupid reason, the lugs in all panels are only rated for 75 degrees. The NEC lists ampacity of wire for both 90 and 75 degrees, and you have to go with the 75 degree column. A lot of people see the 90 degree column and it's slightly higher ampacities and use that for their load calculations, and they're wrong.

MrMark is right, #2 aluminum is NOT good for 100amps. The "master electrician in 5 states" is making a fool of himself, and an IBEW instructor who (a) is ignorant of the NEC and (b) can't think of a better come-back than "you drive a prius" kind of scares me.

I am not a fan of unions (Lets not go there) but one of the IBEW's things one could admire is their training program.....

 

[T VETTE]

Found this to be very interesting to read as for wiring value.

Wonder why some of these threads end up this way though.