mike93lx
ALLIANCE MEMBER
Aluminum will cost a 1/4 of that
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New service or sub panel advice needed
- Thread starter ururk
- Start date
What size/type would you suggest? It seems like there are a bevy of options for aluminum (I keep seeing "mobile home feeder" as a suggestion). My goal is:Aluminum will cost a 1/4 of that
* provide 60A service to barn, install 100A capable conductor
* run about 120', assume 145' max
I'm fine with aluminum as long as I'm able to install it in a way that I feel safe. I know there's a grease, and that there are special clamps to use in some circumstances.
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48windsor
Well-known member
Interesting! Thanks for the idea.
take pictures of a tape measure showing depth of trench.
May save hassles later from an inspector
In the past I have taken pieces of 2" pipe or conduit and placed them directly on the buried line so you can see the line if you look down into it and there is room to drop a tspe measure down to verify depth. Not sure if it will fly with all inspectors but along with pics it should satisfy most.take pictures of a tape measure showing depth of trench.
May save hassles later from an inspector
FWIW we buy a relatively small amount from the local electrical supplier, maybe 10k a year. Big box store prices are very close on most of it, it's more of a convenience than anything. We buy from several HVAC suppliers and get better pricing then the big box but we are buying between 100k and 400k a year.
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mike93lx
ALLIANCE MEMBER
What size/type would you suggest? It seems like there are a bevy of options for aluminum (I keep seeing "mobile home feeder" as a suggestion). My goal is:
* provide 60A service to barn, install 100A capable conductor
* run about 120', assume 145' max
I'm fine with aluminum as long as I'm able to install it in a way that I feel safe. I know there's a grease, and that there are special clamps to use in some circumstances.
The anti oxidant paste is generally unnecessary. Follow the manufacturer's instructions (of the wire).
I would run #2 and breaker it at 90a. That extra 10a will require upsizing
If conduit end to end, xhhw. If you want to direct bury, mhf
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Cruzan80
Well-known member
If conduit end to end, might as well use 1—1—1—3 and get the full 100A you want. For some reason, everyone keeps recommending 90 regardless. Only solid reason I was given was if you are using mhf, as it doesn't come in 100A version, only 2—2—2—4. Nobody could give a good reason why to only run 90 if using individual wires, except "Nobody actually needs 100A, so save money". Which isn't actually a reason...
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mike93lx
ALLIANCE MEMBER
If conduit end to end, might as well use 1—1—1—3 and get the full 100A you want. For some reason, everyone keeps recommending 90 regardless. Only solid reason I was given was if you are using mhf, as it doesn't come in 100A version, only 2—2—2—4. Nobody could give a good reason why to only run 90 if using individual wires, except "Nobody actually needs 100A, so save money". Which isn't actually a reason...
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You are acting like 100a is something significantly different than 90a. In a shop, it is very hard for a single person to use even 90a. Going bigger is just a waste of money, in most situations.
Using your logic, why stop at 100a?
No one is telling him he can't run 100a. I offered a suggestion of what I would do
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Cruzan80
Well-known member
Because that is what the OP asked about. Why install 20A breakers at all, instead of just 15s? 14ga is cheaper than 12. Sorry, I dont buy the slippery slope argument. All I am saying is because you (generic you) dont think the OP needs the extra 10A, you arent going to tell him how to wire it, and only tell him about 90A options? Again, for MHF, it makes sense, as the next size up made is overkill for 100A. But the point of individual conductors is to size them for what you need. And if the OP says 100A, my answer will include what is need for 100A. I may offer suggestions for other amps as well, but when I originally asked the same kind of question over a year ago, it was pulling teeth to have someone actually answer me, instead of tell me why I only needed 90. I knew what I was wiring, had good reasons why I wanted 100 instead of 90, but everyone was trying to tell me why I was wrong instead of actually answering the question I asked. Trying to save the OP from the same aggravation.
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mike93lx
ALLIANCE MEMBER
Because that is what the OP asked about. Why install 20A breakers at all, instead of just 15s? 14ga is cheaper than 12. Sorry, I dont buy the slippery slope argument. All I am saying is because you (generic you) dont think the OP needs the extra 10A, you arent going to tell him how to wire it, and only tell him about 90A options? Again, for MHF, it makes sense, as the next size up made is overkill for 100A. But the point of individual conductors is to size them for what you need. And if the OP says 100A, my answer will include what is need for 100A. I may offer suggestions for other amps as well, but when I originally asked the same kind of question over a year ago, it was pulling teeth to have someone actually answer me, instead of tell me why I only needed 90. I knew what I was wiring, had good reasons why I wanted 100 instead of 90, but everyone was trying to tell me why I was wrong instead of actually answering the question I asked. Trying to save the OP from the same aggravation.
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Need a ladder to get down from your soapbox?
I offered a suggestion, so did you. Let's move on
Cruzan80
Well-known member
Sorry you feel that way. Wasn't directed at you (hence the mention of "Generic You").
So... someone must have deleted their post. They had listed the conduit/wire (with designation) combination for 100A - would appreciate it.
Why 100A vs 90A? I don't have a good reason. Once I know the breakdown in cost, I would make a decision on whether the extra cost was worth the extra 10A.
Will I even go above 60A? Very unlikely. I want some overhead for future upgrades if I find using a portable electric space heater, stuff I won't necessarily factor in (fridge, dehumidifier), 3D printer, and running my CNC, while doing dust extraction AND running a table saw runs into some limit. At the moment I cannot fathom a scenario where I use more than 60A simultaneously, but I want to prepare for the future.
Why 100A vs 90A? I don't have a good reason. Once I know the breakdown in cost, I would make a decision on whether the extra cost was worth the extra 10A.
Will I even go above 60A? Very unlikely. I want some overhead for future upgrades if I find using a portable electric space heater, stuff I won't necessarily factor in (fridge, dehumidifier), 3D printer, and running my CNC, while doing dust extraction AND running a table saw runs into some limit. At the moment I cannot fathom a scenario where I use more than 60A simultaneously, but I want to prepare for the future.
OK, so I spent some time this morning figuring things out. I have two paths - 90A or 100A. Breakdown, using Aluminum wire. I did not calculate cost of fittings, mogul fittings, or risers into the house. Shipping is baked into the price - a 500' spool of 1 AWG or 2 AWG shipped is cheaper than local big box stores.
100A - $462.55:
three 1 AWG XHHW-2 conductors
one 2 AWG XHHW-2 conductor
1-1/4 EMT (in house) - 30'
1-1/2 Schedule 80 (outside) - 80'
90A - $335.76
three 2 AWG XHHW-2 conductors
one 6 AWG XHHW-2 conductor
1-1/4 EMT (in house) - 30'
1-1/4 Schedule 80 (outside) - 80'
It'll probably come to a $200 difference once I factor in fittings, and extra effort to run the heavier conductors.
100A - $462.55:
three 1 AWG XHHW-2 conductors
one 2 AWG XHHW-2 conductor
1-1/4 EMT (in house) - 30'
1-1/2 Schedule 80 (outside) - 80'
90A - $335.76
three 2 AWG XHHW-2 conductors
one 6 AWG XHHW-2 conductor
1-1/4 EMT (in house) - 30'
1-1/4 Schedule 80 (outside) - 80'
It'll probably come to a $200 difference once I factor in fittings, and extra effort to run the heavier conductors.
Cruzan80
Well-known member
Terry D
Well-known member
1 1/2 PVC conduit with (3) #1 XHHW alum. and (1) #6 alum. XHHW EGC would give you 100 amps.
There is no voltage drop figured in here
There is no reason to put schedule 80 underground, use schedule 40
There is no voltage drop figured in here
There is no reason to put schedule 80 underground, use schedule 40
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When I look at the tables in the NEC, Table 310.15(B)(16), 1 AWG XHHW-2 aluminum is rated up to 115 amps - but when I plug my numbers into Southwire's voltage drop calculator:
https://www.southwire.com/calculator-vdrop
I get an error:
1 AWG aluminum may not carry 100.0 amps.
Are they assuming Types TW, UF, since their calculator lists 85 as the max current capability?
I downloaded an Excel spreadsheet calculator, voltage drop came out as 2.3%.
https://www.southwire.com/calculator-vdrop
I get an error:
1 AWG aluminum may not carry 100.0 amps.
Are they assuming Types TW, UF, since their calculator lists 85 as the max current capability?
I downloaded an Excel spreadsheet calculator, voltage drop came out as 2.3%.
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Terry D
Well-known member
You are looking in the 90 degree column, you have to use the 75 degree column because that is what the temperature rating of your terminals is. The 90 degree column is pretty much for a start in derating calculations. What is the distance of the run. And it also has been already said that there is errors in that calculator
Maximum distance would be 145 feet - best I can tell (wheel over ground, tape measure inside) it will be about 120' from main electrical panel to sub panel.You are looking in the 90 degree column, you have to use the 75 degree column because that is what the temperature rating of your terminals is. The 90 degree column is pretty much for a start in derating calculations. What is the distance of the run. And it also has been already said that there is errors in that calculator
James-W
Well-known member
When I built my garage I had the power company run a 200 amp service line to the garage. My house has a 100 amp service and I felt it made much more sense to run a new electrical service from the street rather than come off my main house electrical service. Yes, now I have to two meter charges, but I really don't care. With a new 200 amp service in the garage, I have all the power I will need for future equipment I might decide to purchase. I seriously doubt I will ever need that much electrical power in my garage, but if I do, it is already there.
I am totally in favor of being proactive rather than being reactive. We never know what the future will bring and therefore we never know exactly how to plan for the future. But in a case like this, since we are building a shop, we have to assume as time goes by we will get more equipment. Some of the new equipment may very well draw more power than the equipment we currently have. That being the case, we may as well plan for that right now and eliminate the need to rip out the existing power lines and running new larger ones.
I am totally in favor of being proactive rather than being reactive. We never know what the future will bring and therefore we never know exactly how to plan for the future. But in a case like this, since we are building a shop, we have to assume as time goes by we will get more equipment. Some of the new equipment may very well draw more power than the equipment we currently have. That being the case, we may as well plan for that right now and eliminate the need to rip out the existing power lines and running new larger ones.
This option would be very expensive for me. I checked with the local power company already (DTE). I would be responsible for running the conduit, paying for the copper wire from barn to pole, and paying them $12/ft (around 200 feet from the pole) to pull the wire. I also got an estimate from an electrician - quote was $8,000 to do this (not including the DTE fees).When I built my garage I had the power company run a 200 amp service line to the garage. My house has a 100 amp service and I felt it made much more sense to run a new electrical service from the street rather than come off my main house electrical service. Yes, now I have to two meter charges, but I really don't care. With a new 200 amp service in the garage, I have all the power I will need for future equipment I might decide to purchase. I seriously doubt I will ever need that much electrical power in my garage, but if I do, it is already there.
I have a 200A service at the house - upgrading the service in the future would be something like $40, with DTE upgrading the line up to the house as part of that (upgrading the service might cost more than what I wrote, but still practically free since they would do all the labor up to the house). My basic plan was to provide 60A to the barn initially, and if I end up needing more replace the 60A breaker with a 100A and upgrade the house to a 300A service. But, 60A breakers are not sized for the gauge of wire I'd need for a 100A feeder, so that means I need to also put in a larger breaker at the house.
Terry D
Well-known member
Maximum distance would be 145 feet - best I can tell (wheel over ground, tape measure inside) it will be about 120' from main electrical panel to sub panel.
I personally wouldn't be worried about a voltage drop at that distance, you could bump it up one size, but I wouldn't be concerned
I'd prefer not to go up a size - I just want to be assured that 1-1-1-6 AL XHHW-2 at 145' will be sufficient for 100A.I personally wouldn't be worried about a voltage drop at that distance, you could bump it up one size, but I wouldn't be concerned
The 75C column in NEC Table 310.15(B)16) lists 100A as the allowable ampacity. I don't understand why a Type XHHW-2 would fall under the 75C ratings, and not the 90C column.
Terry D
Well-known member
I'd prefer not to go up a size - I just want to be assured that 1-1-1-6 AL XHHW-2 at 145' will be sufficient for 100A.
The 75C column in NEC Table 310.15(B)16) lists 100A as the allowable ampacity. I don't understand why a Type XHHW-2 would fall under the 75C ratings, and not the 90C column.
The temperature ratings refer to the ratings on the breakers and the lugs in the panels. 90 degree rated equipment is not common, that why the 75 degree column is used since 75 degree equipment is common. There are some cables, NM-b is one, that are considered a 60 degree cable, so the 60 degree column has to be used no matter what. The 90 degree column is allowed to be used as a starting point when you have to derate the conductors ampacity. They will let you start with the higher ampacity in your calculations. I hope im right on this, someone correct me if wrong
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Gotcha!The temperature ratings refer to the ratings on the breakers and the lugs in the panels. 90 degree rated equipment is not common, that why the 75 degree column is used since 75 degree equipment is common. There are some cables, NM-b is one, that are considered a 60 degree cable, so the 60 degree column has to be used no matter what. The 90 degree column is allowed to be used as a starting point when you have to derate the conductors ampacity. They will let you start with the higher ampacity in your calculations
Mike Holt has some good videos on YouTube as well, he has been teaching code classes for many years.I've also been watching YouTube, been looking over the "Electrician U" channel which has been very helpful.
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Small, tiny update.
I called a few local electrical supply houses - one of them was cheaper than the place I found online. So, I know who my supplier is!
However, I got a lot of conflicting remarks by the companies I talked with. Bottom line... I should talk to the inspector to make sure they are OK with whatever I choose. I've emailed the township my question. I cited a NEC table, and used the correct terminology... so hopefully I get a helpful response.
And as far as the 100A/90A breaker - I may end up going with 90A.
I called a few local electrical supply houses - one of them was cheaper than the place I found online. So, I know who my supplier is!
However, I got a lot of conflicting remarks by the companies I talked with. Bottom line... I should talk to the inspector to make sure they are OK with whatever I choose. I've emailed the township my question. I cited a NEC table, and used the correct terminology... so hopefully I get a helpful response.
And as far as the 100A/90A breaker - I may end up going with 90A.
mike93lx
ALLIANCE MEMBER
Be careful about what the inspector says. They don't get to make rules, only enforce them.
I get that sometimes it is easiest to go along but if they are talking about significant added cost or work, make sure they prove the requirement.
I get that sometimes it is easiest to go along but if they are talking about significant added cost or work, make sure they prove the requirement.
Certainly! In my email I stated which conductor size I wanted to use, based on the NEC tables, and wanted confirmation that I was interpreting the code correctly.Be careful about what the inspector says. They don't get to make rules, only enforce them.
I get that sometimes it is easiest to go along but if they are talking about significant added cost or work, make sure they prove the requirement.
One thing to always keep in mind about supply houses, the guys working there are not out in the field for one reason or another. Sometimes you will have a retired master electrician working there, that guy might have been really good and just enjoys seeing all the same guys he saw when working or he might have been an absolute hack.
A lot of the counter guys will have some knowledge but it might just be based on what they sell to other contractors and those guys might or might not be using the correct product for a given application.
Knowing the code and being able to prove that you are correct goes a long way. I have on more then one occasion had a meeting with an inspector and been able to prove that my way met code 100% I have also had occasions that the inspector had a legit problem and we were able to talk about an acceptable solution.
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A lot of the counter guys will have some knowledge but it might just be based on what they sell to other contractors and those guys might or might not be using the correct product for a given application.
Knowing the code and being able to prove that you are correct goes a long way. I have on more then one occasion had a meeting with an inspector and been able to prove that my way met code 100% I have also had occasions that the inspector had a legit problem and we were able to talk about an acceptable solution.
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The last guy I spoke to admitted as much (not an electrician). He suggested I reach out to the inspector - he’s had enough people who have asked to return (used) feeder because it didn’t meet the inspector’s approval.One thing to always keep in mind about supply houses, the guys working there are not out in the field for one reason or another. Sometimes you will have a retired master electrician working there, that guy might have been really good and just enjoys seeing all the same guys he saw when working or he might have been an absolute hack.
Got a response from the inspector:
Now... let's analyze this a bit, looking at table 310.15(B)(16):
100A
Aluminum
#1 is the smallest conductor permitted for 100A in the 75C column
#2 is the smallest in the 90C column
Copper
#3 is the smallest in the 75C column
#3 is the smallest in the 90C column
Over 130 feet, voltage drop:
Alu #1: 2.12%
Alu #2: 2.67%
Cu #2: 1.69%
Cu #3: 2.13%
It *seems* like Alu #2 is too small based on NEC. What should I make of this?
You can use 2-2-2-6 underground service entrance (USE) comes as a cable for direct burial. If in conduit use THHW individual conductors same size. Copper or aluminum may be used although copper is rated higher and more expensive.
Now... let's analyze this a bit, looking at table 310.15(B)(16):
100A
Aluminum
#1 is the smallest conductor permitted for 100A in the 75C column
#2 is the smallest in the 90C column
Copper
#3 is the smallest in the 75C column
#3 is the smallest in the 90C column
Over 130 feet, voltage drop:
Alu #1: 2.12%
Alu #2: 2.67%
Cu #2: 1.69%
Cu #3: 2.13%
It *seems* like Alu #2 is too small based on NEC. What should I make of this?
mike93lx
ALLIANCE MEMBER
As stated here already, #2 AL cannot be used for 100a to a subpanel.
If you are OK with 90a, #2 AL is fine. There is nothing to debate on that.
Buy copper if you want less money or maybe a little smaller conduit
If you are OK with 90a, #2 AL is fine. There is nothing to debate on that.
Buy copper if you want less money or maybe a little smaller conduit
I know that - why did the inspector say #2 AL was fine? Was he being lazy? I'm not doubting the NEC code - I'm just a little confused why he would say to use #2.As stated here already, #2 AL cannot be used for 100a to a subpanel.
If you are OK with 90a, #2 AL is fine. There is nothing to debate on that.
Buy copper if you want less money or maybe a little smaller conduit
wyliesdiesels
Well-known member
USE rated cable cannot be used inside regardless of conduit.
wyliesdiesels
Well-known member
I know that - why did the inspector say #2 AL was fine? Was he being lazy? I'm not doubting the NEC code - I'm just a little confused why they would say that.
not sure how lazy would be a good description.
ignorant or un-knowledgable is a better word
wyliesdiesels
Well-known member
Is there an outside terminal block one uses to connect the inside wiring to the outside then?
If you buy MHF- mobile home feeder, it will be a lot easier. no splices needed.
if you must use USE wire, then you can get a junction box and split bolts or polaris connectors
mike93lx
ALLIANCE MEMBER
I know that - why did the inspector say #2 AL was fine? Was he being lazy? I'm not doubting the NEC code - I'm just a little confused why he would say to use #2.
What he will pass and what is code don't have to line up. He can be wrong and in this case, he is exactly that.