100A subpanel

[LutzTD]

Hi,
Im gathering materials to add a 100A subpanel in my phase 2 garage addition. The particulars. The garage is 100% independent from the house, having its own 200A service and separate meter. I have a 200A load center in the phase 1 garage with multiple circuits for lights and machines. The subpanel would be mounted on the front wall of the phase 2 addition 40 feet away from the main load center, I will follow the rafters with the wire so the run could be as long as 100 feet. I will put the wire in conduit.

I want to use a GE 100A 20 circuit load center so I can share breakers

what size wire, prefer copper?
what size conduit so its not too small for the selected number and size conductors/load
from what Ive read I need to add a ground bar in the load center?
remove the green screw from the neutral bar?
add 2 ground rods outside with #4 copper wire?

this will be inspected by the county when Im done

 

[yaidunno]

I'm in the same boat. I just picked up a Square D QO 100A main. I'll be running 1/0 aluminum SER from the house (200A). The run is about 100 feet, so copper would get spendy quick. 1-1/2" conduit is in the plan. 2" if necessary, I've got no reservations for either size at this point. From all the reading I've done, your correct on isolating the neutral, and adding a separate ground bar. 2 ground rods seems to be the standard followed, although i cant comment on ground wire size.

I'll be keeping an eye on this thread to confirm my thoughts and learn a thing or 3.

 

[pattenp]

If subpanel is in same structure as the main service panel then the additional ground rods at the subpanel are not necessary.

 

[Samh]

If subpanel is in same structure as the main service panel then the extra grounds are not necessarily.

^^This You only want one path to ground.

 

[LutzTD]

If subpanel is in same structure as the main service panel then the extra grounds are not necessarily.

excellent, one less thing. thanx

 

[TAMPAGT07]

Hey Lutzy, you getting any flooding at your place?

 

[pattenp]

And do keep neutrals isolated from ground in all panels after the main service panel. The first main disconnect location is the only place that the neutral and ground are to be bonded.

 

[wyliesdiesels]

Hi,
Im gathering materials to add a 100A subpanel in my phase 2 garage addition. The particulars. The garage is 100% independent from the house, having its own 200A service and separate meter. I have a 200A load center in the phase 1 garage with multiple circuits for lights and machines. The subpanel would be mounted on the front wall of the phase 2 addition 40 feet away from the main load center, I will follow the rafters with the wire so the run could be as long as 100 feet. I will put the wire in conduit.

I want to use a GE 100A 20 circuit load center so I can share breakers

what size wire, prefer copper?
what size conduit so its not too small for the selected number and size conductors/load
from what Ive read I need to add a ground bar in the load center?
remove the green screw from the neutral bar?
add 2 ground rods outside with #4 copper wire?

this will be inspected by the county when Im done

#3 CU or #1 AL. So 3 #3 CU wires with 1 #8 for the EGC or 3 #1 AL wires with 1 #6 AL wire for the EGC. CU wire will add up quick. Todays AL wire is far superior than the bad stuff from the 60s and 70s.

I would use SER as it will save the hassel of installing conduit and then pulling wire.

If u step the main breaker down to 90a then u could go with #2 AL SER and save quite a bit!

If u do use conduit, use 2"

U need to buy a ground bar kit if the panel doesnt come with one

As pattenp said, u dont need rods if the panel is in the same structure. Your main panel should already have rods.

I'm in the same boat. I just picked up a Square D QO 100A main. I'll be running 1/0 aluminum SER from the house (200A). The run is about 100 feet, so copper would get spendy quick. 1-1/2" conduit is in the plan. 2" if necessary, I've got no reservations for either size at this point. From all the reading I've done, your correct on isolating the neutral, and adding a separate ground bar. 2 ground rods seems to be the standard followed, although i cant comment on ground wire size.

I'll be keeping an eye on this thread to confirm my thoughts and learn a thing or 3.

Your situation is a little different than the OPs as you are feeding a detached structure. So u need grounding electrodes.

If subpanel is in same structure as the main service panel then the extra grounding electrodes are not necessary.

fixed it for u!

^^This You only want one path to ground.

Contrary to popular belief, u can have mulyiple grounding electrodes on one service and at different locations.

 

[pattenp]

fixed it for u!

Thanks. I was answering using my smart phone and it's a joke trying to use voice to text.

 

[theoldwizard1]

If u step the main breaker down to 90a then u could go with #2 AL SER and save quite a bit!

If u do use conduit, use 2"

To add some clarity, you can use a 100A panel only feed it from a 90A breaker. As stated, you will save a lot on the cable !

 

[yaidunno]

Your situation is a little different than the OPs as you are feeding a detached structure. So u need grounding electrodes.

Correct. For some reason i was under the impression that the OP's was detached as well. My bad.

 

[wyliesdiesels]

Thanks. I was answering using my smart phone and it's a joke trying to use voice to text.

Yeah my dumb smartphone iPhone 5s isnt very smart. Thats why i turned off autocorrect and dont use speech to text. I try to proof read everything...

 

[LutzTD]

Hey Lutzy, you getting any flooding at your place?

not too bad. Today in front I had a lake by the road and in the back corner, but it doesnt get deep, doesnt approach any structures and dissipates quickly. We got a lot of rain today and a lot of close lightning strikes.

 

[LutzTD]

I would use SER as it will save the hassel of installing conduit and then pulling wire.

If u step the main breaker down to 90a then u could go with #2 AL SER and save quite a bit!

I was planning to run the line along the steel roof girts and then down the block wall, which I assumed required the conduit. I also assumed the discrete wire would be cheaper, what do you think?

do you think I will notice any functional difference with a 90A breaker as opposed to the 100A?

 

[Bates]

I'm not sure about NEC rules, but here's what my OEC requires in ontario, canada.

-Forget about 2" conduit, that's for 200A panels using 3/0 wire.
-Never use aluminum unless its underground USCI90 triplex cable.
-If you really want conduit, use 1 1/4" and #3 CU with #6 ground.
-To save money, use 3c/3 AC90 also known as BX with 100A breaker.
-Always pull the green bonding screw on a subpanel where you have run a ground wire.
-The ground wire goes to the case, not the neutral bar like in the main service panel.
-Your main panel will only require a ground lug or bar if there isn't a spot available.
-Ground rods/plates are for main services or a few other specialized applications.

Again, check your local codes, this is mine. OEC tends to be the strictest code book around.

One last note: A shop across the street from my bosses had a fire due to improper ground connections in the subpanel. They had hooked the ground to the neutral bar and pulled the bonding screw which meant when a fault happened, it had no place to go besides in a big circle.

 

[wyliesdiesels]

I'm not sure about NEC rules, but here's what my OEC requires in ontario, canada.

-Forget about 2" conduit, that's for 200A panels using 3/0 wire.
-Never use aluminum unless its underground USCI90 triplex cable.
-If you really want conduit, use 1 1/4" and #3 CU with #6 ground.
-To save money, use 3c/3 AC90 also known as BX with 100A breaker.
-Always pull the green bonding screw on a subpanel where you have run a ground wire.
-The ground wire goes to the case, not the neutral bar like in the main service panel.
-Your main panel will only require a ground lug or bar if there isn't a spot available.
-Ground rods/plates are for main services or a few other specialized applications.

Again, check your local codes, this is mine. OEC tends to be the strictest code book around.

One last note: A shop across the street from my bosses had a fire due to improper ground connections in the subpanel. They had hooked the ground to the neutral bar and pulled the bonding screw which meant when a fault happened, it had no place to go besides in a big circle.

He could step the conduit down but 2" will make it a breeze...And if he went with SER, then he doesnt even need conduit.

nothing wrong with using AL wire.

Grounding electrodes ARE REQUIRED for detached structures in the US. However, the OP doesnt need them because he's installing a subpanel in the same structure as the main service panel which should already have grounding electrodes.

The Canadian code about not having grounding electrodes or plates in more than one place doesnt make sense because electrodes are for grounding lightning, limiting voltage to ground, etc. Ive read that some people in canada think the reason for the code is so u dont have ground loops but that doesnt make sense either because of ehat electrodes are actually used for...Millions of structures in the US have multiple grounding electrodes on the same service and have no issues...

And this is just the reason why posting canadaian codes doesnt help someone in the US...

 

[Bates]

I didn't know you guys did things so different. You don't have AC90? that blows my mind!

 

[wyliesdiesels]

I didn't know you guys did things so different. You don't have AC90? that blows my mind!

U know what. I made a mistake. For some reason when i read AC90 i was thinking of TECK90 cable which IS a canadian product.

Yes we do have AC/armored cable. It replaced BX...

I will edit my post.

 

[LutzTD]

is this wire OK? I would like to run it in 1-1/2 conduit as I cannot bend 2". Is 1-1/2 OK?

 

[pattenp]

is this wire OK? I would like to run it in 1-1/2 conduit as I cannot bend 2". Is 1-1/2 OK?

If the wire is going to be inside the structure then no. If it is only USE rated then it has to be used outside and terminated outside.

 

[Wangstang]

Just to clarify, you already have a 200 amp meter in place and 200 amp panel...you aren't in the planning stage.... right?

The reason I ask is I upgraded my home 200 amp meter base to a 400 amp meter base and then split the service so I can run both my shop and house off of one meter. It cost some money up front but I know I'm going to be here for a long darn time and I expect family to be here as well and the power company charges $20 a month for every additional meter base you have on your property after the initial one on the residence. In the long run, the cost to upgrade the meter base to 400 amp worked out to be cheaper than going with two separate meters. Three years ago Milbank was the only company with a 400 amp meter base that had the same standard width as most 200 amp meter bases...like it replaced. It is a few inches taller but that was no problem to accommodate.

Wes

 

[wyliesdiesels]

is this wire OK? I would like to run it in 1-1/2 conduit as I cannot bend 2". Is 1-1/2 OK?

If the wire is going to be inside the structure then no. If it is only USE rated then it has to be used outside and terminated outside.

According to specs on southwires site, its dual rated....but who knows if its the same as the one at home depot.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet12

 

[LutzTD]

Just to clarify, you already have a 200 amp meter in place and 200 amp panel...you aren't in the planning stage.... right?

The reason I ask is I upgraded my home 200 amp meter base to a 400 amp meter base and then split the service so I can run both my shop and house off of one meter. It cost some money up front but I know I'm going to be here for a long darn time and I expect family to be here as well and the power company charges $20 a month for every additional meter base you have on your property after the initial one on the residence. In the long run, the cost to upgrade the meter base to 400 amp worked out to be cheaper than going with two separate meters. Three years ago Milbank was the only company with a 400 amp meter base that had the same standard width as most 200 amp meter bases...like it replaced. It is a few inches taller but that was no problem to accommodate.

Wes

yes, 200A already installed.

yea, I think they have a min charge, but I use more electric than the minimum anyway just keeping the temp stable and dehumidifying which I cannot shut off here in FLA. They arent additive, so I only get the min charge if I dont use enough power, it isnt added on top of what I use.

Now I wouldnt mind having 400A in the shop

 

[LutzTD]

According to specs on southwires site, its dual rated....but who knows if its the same as the one at home depot.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet12

thanx, I will make sure it is rated for all three, RHH or RHW or USE

any thoughts on minimum conduit size for 3 #1 and 1 #6?

 

[pattenp]

The HD wire is listed as Alumaflex so it should have the RHH/RHW rating.

 

[LutzTD]

heres a mail order SER 3 #1 with #2 ground, they charge $36 shipping but still works out cheaper by a long shot if I dont use conduit.

how would I run this inside without conduit? I have block walls and steel roof? Can I use plastic conduit?

 

[pattenp]

The SER only needs to to be in conduit where subject to damage. Use 2 inch Sch 80 PVC conduit for sleeves where needed for protection.

 

[LutzTD]

The SER only needs to to be in conduit where subject to damage. Use 2 inch Sch 80 PVC conduit for sleeves where needed for protection.

can I use sch 40 PVC? Id like to go the whole way and its 40% cheaper

 

[pattenp]

The use of sch 40 vs sch 80 can be somewhat be a subject of opinion because code just says to use sch 80 where subject to damage. So for general protection sch 40 is fine. Like in places where you know the wire will not have a great chance of being damaged. But in places where the wire is exposed to getting hit, cut due to activity then sch 80 should be used. The installation methods for SER are the same as NM-b (Romex). The SER can also be run along running boards for general protection.

 

[LutzTD]

The use of sch 40 vs sch 80 can be somewhat be a subject of opinion because code just says to use sch 80 where subject to damage. So for general protection sch 40 is fine. Like in places where you know the wire will not have a great chance of being damaged. But in places where the wire is exposed to getting hit, cut due to activity then sch 80 should be used. The installation methods for SER are the same as NM-b (Romex). The SER can also be run along running boards for general protection.

yeah thats why I was asking about conduit. I know in my first garage build in OH I had to put romex in conduit where it touched block. I ran it exposed in the wood trusses, but this roof is metal. Ill cost it all out and if the 40% higher cost of the sch80 is not too bad Ill go ahead and do that.

 

[wyliesdiesels]

can I use sch 40 PVC? Id like to go the whole way and its 40% cheaper

Unless it truly is gonna be subject to damage(depends on whos judging), i wouldnt bother pulling SER in conduit. It wont be fun!

 

[LutzTD]

Unless it truly is gonna be subject to damage(depends on whos judging), i wouldnt bother pulling SER in conduit. It wont be fun!

I would just run the wire route then thread the conduit on piece by piece rather than try to pull the whole length, plastic would be even easier. Likely I wont glue it. But things may still change. I am getting my buy list, but still working on the funding......

 

[wyliesdiesels]

Conduit is suppose to be glued and put together before pulling cable through it.

If youre gonna go to the trouble of using conduit why not use individual conductors instead?

 

[LutzTD]

Conduit is suppose to be glued and put together before pulling cable through it.

If youre gonna go to the trouble of using conduit why not use individual conductors instead?

I understand that glueing first is the general rule, but is it a requirement? I am measuring out everything to buy the least amount of wire, in the end the conduit run is going to be around 50ft instead of the 100ft I was napkin sketch estimating.

I found the SER to be cheaper than individual wires, but I still want to run conduit to protect the wire from any kind of accidental damage.

 

[pattenp]

NEC regulations state that conduit is to be a completed assembly before installing wire. The thing is you don't want to get uncured glue on the wire insulation because the glue can damage the insulation.

 

[LutzTD]

NEC regulations state that conduit is to be a completed assembly before installing wire. The thing is you don't want to get uncured glue on the wire insulation because the glue can damage the insulation.

bummer, I dont want to pull this SER, so Im likley just going to be careful with the glue......

 

[sands35]

You could use an expansion joint in the middle. No glue there.

Lots of lube and a buddy helps as will laying out the wire and straightening it out before the pull. It gets pulled as much as it gets pushed into the conduit. Really, 50' should be hard assuming curves are limited. If not, then a few LBs.

 

[LutzTD]

heres my materials pile so far. I got the 60 feet of the $1.65/foot 1113 aluminum SER from wire and cable to go, showed up on my door on a spool in 3 days. shipping was $20, so total was still less the Home Depot price. But Home Depot had the GE 100A main box with copper bus for $60 including 5 20A breakers. I also got the 100A breaker for my primary box. All I need now is conduit and time......

 

[wyliesdiesels]

Is there a specific reason why u want conduit?

SER can be ran without conduit...

 

[LutzTD]

Is there a specific reason why u want conduit?

SER can be ran without conduit...

no "specific" reason. I just dont like unprotected wire runs. I hated the romex runs in my garage in Ohio, even though they were inspected and approved and completely correct...... every time I stored something in the rafters (which was a lot) I was worried about snagging or rubbing or whatever.