100 amp sub panel wiring list

[777mechanic]

finally i'm running my 100 amp sub panel 110 feet from the main panel .
1. ordering aluminum #2 / #2 / #2 / with ground in xhhw-2
2. 1 1/2 schedule 80 pvc in ground and above
3. per national wiring code if in pvc it needs to be 18''

if you see any errors or recommendations please tell me . i live in florida if that helps


also can i run another pvc pipe next other one for air line and cable tv
wiring

 

[pattenp]

PVC can be Sch40 underground and above ground. Above ground where exposed to possible damage should use Sch80.

#2 Al is rated at 90A if you are thinking 100A.

 

[777mechanic]

i know i can use schedule 40 but living in florida , i'd rather not risk it and the cost isn't that much different so i'll go with 80sch. . your correct i went to so many website and found a calculator says i need 1/0 , 1/0 , 1/0 with grd . so is this what your recommend .

and is xhhw-2 correct

 

[sberry]

I use number 2 if it will do, so much cheaper and easier, fits smaller breakers better. Its really a matter of doing some load calc. The main loads are air comp and welding as air can be automatic so this effects it some.
I have put a couple dozen of these in garages, my bud had one with 5 hp comp used EVERY day, he didn't weld, when we did it was me and I can stop if the air would kick on but I have never had one call about a tripped 60. If it would be a problem it could take a 90 which would support a 5 comp and a buzzer level welder.
Modern welders are even less demanding and not everyone uses a heavy comp. Same with lights, now led puts even less demand on garages and most other loads in them are similar to a kitchen, maybe less as they tend to be 1 at a time. Saw, grinder, vacuum etc. While welding a guy isn't usually doing something else.
A lot of times garages are not even considered a big factor in demand calcs as the use is so intermittent. 2 is a little cheaper, very common and way easier to install.

 

[wyliesdiesels]

i know i can use schedule 40 but living in florida , i'd rather not risk it and the cost isn't that much different so i'll go with 80sch. . your correct i went to so many website and found a calculator says i need 1/0 , 1/0 , 1/0 with grd . so is this what your recommend .

and is xhhw-2 correct

Do you really need 100a?

What are your loads?

First step is starting with loads and sometimes even a load calc and THEN size your feeder based off of that.

So many do it backwards and just pick a magic number then end up getting way more than they will ever need.

If this is a one man shop with modest tool use and minimal high draw equipment aka heat, AC, large motors, etc, 90a will be more than enough and going with that size and #2 al mhf will save you a chunk of change that you can use elsewhere.

 

[Crazyjake8493]

Good advice here so far. A 100A sub panel is a good idea to have adequate space for circuits (usually a 12 or 20 space panel in that size), but remember that it does not have to be a 100A feed to that panel.

100A is a lot for a 1 man garage. I ran 2-2-2-4 MHF which was around $1.70/ft if I remember right, and supports up to 90A. I fed it with a 60A breaker since that was the biggest available in the store, and I didn't want to triple the price for a 70 or 90A breaker.

As suggested, do a load calc to find what size feeder you need to the subpanel. If you're looking at a 50 or 60 amp service, which is common for a one-man shop, 2-2-2-4 MHF may still be cheaper than copper rated for 50 or 60 amps, and will give you the option to expand in the future.

 

[Matt Matt]

Good advice here so far. A 100A sub panel is a good idea to have adequate space for circuits (usually a 12 or 20 space panel in that size), but remember that it does not have to be a 100A feed to that panel.

100A is a lot for a 1 man garage. I ran 2-2-2-4 MHF which was around $1.70/ft if I remember right, and supports up to 90A. I fed it with a 60A breaker since that was the biggest available in the store, and I didn't want to triple the price for a 70 or 90A breaker.

As suggested, do a load calc to find what size feeder you need to the subpanel. If you're looking at a 50 or 60 amp service, which is common for a one-man shop, 2-2-2-4 MHF may still be cheaper than copper rated for 50 or 60 amps, and will give you the option to expand in the future.

I like this suggestion! Do a load calculation and if you really feel you need a 100 A, you can upsize the wire by one size just to be on the safe side.

I personally don’t like running #2 AL over 100’ for 100A.

The next situation is how many Breakers do you wish to have in the subpanel?
You might need a main breaker for the subpanel.

 

[sberry]

I agree about the 100 over 100 but the max is 90 and he might not even really need that. Just because there is a 90 in the panel doesn't mean that will be the real applied load. The same is assumed about 120v circuits withba 20 on them. Even heavily loaded it's closer to coming up on 15 than 20.
The main reason for 20 is headroom for motor starts. A bit on occasion for other reasons but it's really rather rare. The wire needs to be thermal protected mainly as those circuits have multiple outlets.

 

[Matt Matt]

I agree about the 100 over 100 but the max is 90 and he might not even really need that. Just because there is a 90 in the panel doesn't mean that will be the real applied load. The same is assumed about 120v circuits withba 20 on them. Even heavily loaded it's closer to coming up on 15 than 20.

And I agree again 100 %. A load calculation needs to be done. He could have a 40 amp electrical heater, some lighting and 60 amp welder, and a 5 hp air compressor that kicks on whenever it wants, well he’s using his plasma cutter.

But… I built this in to a 2 man shop for fun.

Or, his wide 36” belt sander(7.5hp) starts up at the same time as 5hp air compressor... well he is using his 5hp planer, and the 5 hp dust collector.

I think most people do it forward... and just over calculate. Nothing wrong in my books except for a few extra dollars put out for future expansion.

Do it the best can the first time.... regret is something you only pay for!

 

[pattenp]

i know i can use schedule 40 but living in florida , i'd rather not risk it and the cost isn't that much different so i'll go with 80sch. . your correct i went to so many website and found a calculator says i need 1/0 , 1/0 , 1/0 with grd . so is this what your recommend .

and is xhhw-2 correct

Not getting into what amp size you need but to clarify, #1 Al is needed for 100A, not #1/0 Al. And xhhw-2 wire type is fine as long as it's put in conduit.

 

[777mechanic]

so teach me to load calculate each machine and a/c unit

1. 5hp dust collector
2. 7.5hp table saw
3. 1200 a/c unit mini split running dam near year round in florida

1. same dust collector 5hp 220v 1ph
2. sander 7.5 hp 220 1ph
3. same mini split a/c

these two scenarios are always on when woodworking so these are my highest draws at one time , also 5hp air compressor will be cycling at will.

I also run vfd 5hp 3ph cnc mill and lathe, but not at same time as when wood shop is running.

 

[Norcal]

Since it sounds like detached structure has it been built or going to be built? Grounding electrodes such as rods or a UFER need to be added if detached. What type will be determined if built already or detached or not if attached then none required.

 

[mike93lx]

so teach me to load calculate each machine and a/c unit

1. 5hp dust collector
2. 7.5hp table saw
3. 1200 a/c unit mini split running dam near year round in florida

1. same dust collector 5hp 220v 1ph
2. sander 7.5 hp 220 1ph
3. same mini split a/c

these two scenarios are always on when woodworking so these are my highest draws at one time , also 5hp air compressor will be cycling at will.

I also run vfd 5hp 3ph cnc mill and lathe, but not at same time as when wood shop is running.

Can you share the motor nameplates on each of those?

 

[777mechanic]

5hp / 3.7kw / 1725rpm / f.l.a. 27 / 1.5 service factor / dust collector

7.5hp / 5.6kw / 3450rpm / f.l.a. 37 / 1.5 service factor / table saw

both are baldor motors , a/c unit not ordered yet but will try for specs do you need more info

also I didn't include lighting that was my next question about brands of led 4ft or 8ft

 

[TRWham]

Not getting into what amp size you need but to clarify, #1 Al is needed for 100A, not #1/0 Al. And xhhw-2 wire type is fine as long as it's put in conduit.[/QUOTE

Yes, but the higher temp rating of XHHW-2 is useless if the terminations only allow 75C, which is common, so make sure you size it using the right column.

 

[pattenp]

Not getting into what amp size you need but to clarify, #1 Al is needed for 100A, not #1/0 Al. And xhhw-2 wire type is fine as long as it's put in conduit.[/QUOTE

Yes, but the higher temp rating of XHHW-2 is useless if the terminations only allow 75C, which is common, so make sure you size it using the right column.

What higher temp rating? xhhw-2 is 90C wire as are others such as thhn. 90C is only used for derating purposes so 75C is used for sizing this type of single conductor wire. So I'm not following your statement that the higher temp rating is useless. Sounds as if you're saying he is wasting his money buying it because of it's temp rating.

 

[TRWham]

What higher temp rating? xhhw-2 is 90C wire as are others such as thhn. 90C is only used for derating purposes so 75C is used for sizing this type of single conductor wire. So I'm not following your statement that the higher temp rating is useless. Sounds as if you're saying he is wasting his money buying it because of it's temp rating.

I meant not to be confused by the option of a 90C temp rating that probably cannot be applied in this case, just as you said. I would have said the same of THHN or THWN, but XHHW-2 was in play at the time.

 

[sberry]

That is a monster table saw. Most are a HP or 2 max.

 

[sberry]

A wire a size above 2 might not hurt here, 100 breaker. Both those items are heavy.

 

[pattenp]

New to forum: posted these question on a much older thread. I will be helping my son run a line ~100' from his main 400amp house panel to a 100amp square D 8 circuit sub panel at his dock storage shed. Thinking of using MHF 2224 and burying it 18" in 2"#40 conduit. Use a 90 amp breaker in main panel. questions: how hard is it to pull through 2" conduit. Is 2224 hard to bend to connect to sub panel main and main panel 90 amp breaker? Local electrician said i don't need a ground rod for sub panel as main panel is grounded Is this true? Sub panel has 8 breaker slots 4 will be used for 220v 10amp breakers to supple indivdual boat lift motors leaving 4 empty slots. Does this qualify for 6 breaker rule and not needing a main cut off at sub panel? Am i thinking clearly on this I'm not an electrician but I have done my own house wiring when we built the house 20 years ago (no problems) Any help or suggestions would b appreciated Thanks John

The 2-2-2-4 is not bad to work with and easily pulls through 2" PVC conduit. You should have a grounding electrode system for any detached structure with a subpanel. Having more than 6 breakers requires a main disconnect at the detached structure so a lot of inspectors will require it if the panel can hold more than 6 even if less than 6 are installed. It's best to use a main breaker panel.

Just an FYI, you should start your own thread and not piggyback on someone else's.

 

[johnHarley]

Thanks I will start my own thread Sorry

 

[grounded-b]

#2 aluminum is very easy to bend.

You definitely need a made grounding electrode at a detached building - either a ground rod (or 2 ) or a ufer ground (concrete encased electrode)

Difficulty of pulling is determined by total number of bends in run ( not to exceed 360 total degrees per NEC ) and distance. Use of wire pulling lube will help.

6 handle throws or less = 2 double pole breakers and 4 single pole.

Neutral bar shall be insulated from metal enclosure of panel. #4 equipment ground will connect to ground bar, along with grounding electrode conductor

Steve

 

[wyliesdiesels]

so teach me to load calculate each machine and a/c unit

1. 5hp dust collector
2. 7.5hp table saw
3. 1200 a/c unit mini split running dam near year round in florida

1. same dust collector 5hp 220v 1ph
2. sander 7.5 hp 220 1ph
3. same mini split a/c

these two scenarios are always on when woodworking so these are my highest draws at one time , also 5hp air compressor will be cycling at will.

I also run vfd 5hp 3ph cnc mill and lathe, but not at same time as when wood shop is running.

If the HP ratings you have listed are all true HP ratings based on FLA, then that is a lot of HP running.

Many PoCos have limits on HP. In your scenarios, you could have over 20HP running at the same time.

Definitely should check with PoCo to make sure their distribution lines and transformer can handle all that.

 

[777mechanic]

i've been in contact with poco and they want a load calculation just not sure how to do it , thats why i've been asking how to do it. the funny thing is i've called at least 6 electricians and not one call back . my big question is when you do a load calc. i still have 14 more machines , so do you only do the largest or all of them together because that would put me over 200 amp easily .

 

[sberry]

I am not sure how you would do a calc for that other than to estimate how many could be running. If they really asked I would simply say I had someone to it and they came up with 90,, ha,,,,, but peak could be way different than usual or,,, not sure how to word it. A heavy air comp could add to peak.
I have had a LOT on 100 and never trip, a lot with a lot of people.
I have only ran across a couple true overloads in my career, granted I am not working steady but have been around. A fused 60 on a house where they added all electric appliances and a tavern with a shitload of electric fryers, A.C. coolers etc on a hot Friday night fish fry.
I would have to think back about the potential there but it was a huge amount of connected equipment, , way beyond the service rating, 2x maybe more.
You can have a hundred receptacles connected but the only thing that matters is how much is actually running at once. I have 400 service, 95 percent of the time just a few amps, well cycles in 45 seconds, comp runs 3 minutes at 20A and I have a walkin cooler most people don't have, it can run 20 or 30 percent if I am busy, that is 25, electric dryer on low, pressure washer, 25, occasional weld but I bet it's pretty rare to hit 75.

 

[ford33]

You would save some money on wire and conduit and ease of installation if you went with 60 amps. In a small one man residential garage shop it should be plenty of power.

Best to calculate your actual power needs.

 

[sberry]

I have excess because it was cheap and practical for me could have saved another 75$ on the install with a design change but it wouldn't look as cool,, ha. But I had the wire, panels, cost me only 100 in materials and minor time and made for a way better install.
You have motors bigger than most, I think the number 1 over 2 might be worth it in this case. Less thermal expansion on the connectors etc, keep the wire from heating a little less.
It leaves a little more headroom for heavy starts too. Doesn't sound like a few more dollars is a deal breaker in this case for a little better wire.

 

[Matt Matt]

so teach me to load calculate each machine and a/c unit

1. 5hp dust collector
2. 7.5hp table saw
3. 1200 a/c unit mini split running dam near year round in florida

1. same dust collector 5hp 220v 1ph
2. sander 7.5 hp 220 1ph
3. same mini split a/c

these two scenarios are always on when woodworking so these are my highest draws at one time , also 5hp air compressor will be cycling at will.

I also run vfd 5hp 3ph cnc mill and lathe, but not at same time as when wood shop is running.

I have #2,2,2 Alu with #2 copper G feeding my water main.(12’) 100A barker from 200A. My woodworking shop. No grounding (extra G rods are required under city limits,) if attached to city plumbing.... with a few extra requirements.

I’ll give you my situation. My woodworking shop that has 100 amp main has a 5 hp dust collector(DC) 23 A FLA. For one second it will pull 170 A TRMS. It is on a 30 amp breaker( that has never tripped 5years). My tablesaw is a 5 hp three-phase 13A(The multiplier for three phase to single phase amps is 1.73 so= 22.5 SP FLA) on VFD. My planer is 4 hp 16 FLA . My jointer is 4 hp 16 FLA. I can’t start the dust collector and any one of the machines within about 10 seconds of each other. The main breaker blows. The DC (dust collector)is my biggest culprit. With all the blast gates open and full draw it pulll’s 19 A TRMS. With only one 5 inch gate open, I’m pulling a about 13 A. With 2 6 inch blast gates fully open I am pulling my maximum CFM and my maximum 19.2 A. Now my air compressor is a three phase air compressor powered by a VFD. It too is a 5 horse power. Using a VFD, it’s ramp up never exceeds 30 apps single phase. This my add confusion, it might add some clarification...

I did use the Bill Pentz design, but I did build my own design fan/turbine. I built that whole cyclone from scratch. I didn’t buy a thing except for the metal and motor. Even the hub assembly I built myself. I’ll do a edit, when I find it.

Here’s a few videos from the past.

I find my woodworking shop is the most hungry start up current. So my personal suggestion is don’t cheap out on anything, don’t cut any corners with your main feed line if you feel you need 100 A.

I remember the first Ford dealership I worked in(Ya,I used to fix cars for about 5-6 years in dealerships(Ford, Suzuki, Saturn, Saab, Isuzu & GM) it had (in the the 20 Bay) 10 foot banner saying “do it right the first time, it’s the only time you’re paid!” I’ll take that banner to my grave!

Where I am blessed a little bit is, I have a 50 kVA transformer feeding my property. It is shared between four other neighbouring properties. I just need to be mindful of what I’m doing and when I’m doing it to not dim my neighbours lights. When my dust collector starts, it dims my lights and it dims most my neighbours lights(i’ve been told) i’ll keep my fingers crossed, non of my neighbours will complain to the poco of my industrial shop in a residential setting.

More backstory. https://www.garagejournal.com/forum/showthread.php?t=382587

 

[TRWham]

i've been in contact with poco and they want a load calculation just not sure how to do it , thats why i've been asking how to do it. the funny thing is i've called at least 6 electricians and not one call back . my big question is when you do a load calc. i still have 14 more machines , so do you only do the largest or all of them together because that would put me over 200 amp easily .

Article 220 covers load calculations.