Electrical sub-panel question

[WranglerX]

Call electrician, dig a trench from main panel to sub panel, lay in conduit and pull in wire and have electrician connect 100 amp sub panel at "shop" and at main panel.... Do it right, be safe, be happy forever...

Dale

 

[WranglerX]

Grounding is a most misunderstood element of electrical work. I always refer to the Apprentice School Textbook "Soares Book on Grounding and Bonding". Available at Amazon. That and one of the good books on DIY electrical work get me through most situations w/o digging out the NEC. There is a situation that extra grounding can create a "Ground Loop" which can be detrimental to electronic equipment especially.

Ron

YES.....

Grounding - Safety Fundamentals (1hr:13min:19sec) - YouTube

Dale

 

[CobyRupert]

Ground rod at a remote subpanel is required by Code, but IMHO it’s a big “meh”. It helps to keep static charge on metal surfaces low..big whoop.
Relying on a ground rod and earth as the path for fault current to get back to the (grounded) transformer winding isn’t a very good path. You want a low resistive path that results in high (fault) currents that trips a breaker. Low faults currents that don’t trip the breaker leaves things dangerously energized.
IMHO its more important a good ground conductor gets run to the sub-panel from the main panel (where the ground is bounded to the neutral and has a conductive path back to the opposite end of the transformer winding from where the current originated).

 

[RoyKing]

Sub panels are supposed to have ground and neutral. Ground rod connections can be the weather head, meter can, first disconnect. Most ground rod connections are very poor after a few years. the Clamp gets loose and corroded. A 10' rod seldom get you within 20 ohms, doubling to a 20' and using and exothermic weld will insure far less damage from lightening. Communications cabinets require 5 ohms or less.

 

[Tractor Seabee]

Codes and common sense don't always mesh. Having been a quasi Building/Plumbing/Electrical Inspector in conjunction with QC duties I have concluded a lot of code stuff is promulgated by manufacturers to sell their new ideas to satisfy a once in 10 million casualties. Arc fault being the latest and now it is expanding. At one time I had a shelf full of codes, standards, and reference materials almost 10' long and the stuff changes every three years. The digital world eliminated those hard copies.

Ron

 

[dragoneggs]

Code around here I believe is two rods six feet apart. Anyone that can pound a ground rod in undisturbed soil... I mean rock, has my vote. I installed a sub panel to my detached shop running 6-3 copper. Still need to add a ground rod or two.

I have three 220v circuits one being a 30amp for my welder and plasma cutter. The other two 220v are 20amp circuits that power my table saw, band saw, planer, jointer, and air compressor As it is a one man shop I am only running one of the big tools at a time and the compressor is on its own, since I never know when that will kick on. Beyond that I have two 110 20amp circuits for lighting, hand tools, a mini water heater, dust collector and air filter. Also have the original single 110v for the basic lighting and original outlets.

 

[BrokenTrack]

My ground is too rocky, and thus too close to ledge rock to drive a ground rod that way, so I do not even try. I dig a trench with my backhoe as deep as I can go, and then put the ground rod in the trench, and then back-fill.

This was a trick an electrician showed me when we were laying a lot of underground cable, and i thought it was a much better way to "drive" ground rods in the ground.

I am not sure what other electricians think of it, but I see no reason why it is not a good way to do it.

 

[BrokenTrack]

YES.....

Grounding - Safety Fundamentals (1hr:13min:19sec) - YouTube

Dale

Hey thanks guys, I will have to look into that more, because I had never heard of that phenomenon.

In my latest work, I grounded my generator engine (dedicated genset) from engine to frame, then frame to ground. But I also did that with the generator head, going from generator, to generator frame, to ground. But also the generator panel to ground. I think that would be well within reason.

 

[BrokenTrack]

Talk about Project Creep...why not just upgrade your shop to 3 phase power while you are at it! (LOL)

I actually thought about it. For $1700 I could switch over to a 3 phase power unit. Go with single phase for the house, and 3 phase for the shop...

 

[CobyRupert]

In my latest work, I grounded my generator engine (dedicated genset) from engine to frame, then frame to ground. But I also did that with the generator head, going from generator, to generator frame, to ground. But also the generator panel to ground. I think that would be well within reason.

The bigger question is did you bond the neutral and ground at the genny?
Hopefully not, unless your transfer switch also switches (& isolates) the neutral(s).

 

[Industrial Toys]

I have looked around friends yards and found Galvanized "stuff" . Buried a Galvanized truck headache rack for a ground, here a few years ago. In my way of thinking, a regulation ground rod just doesn't have much surface area.

 

[BrokenTrack]

The bigger question is did you bond the neutral and ground at the genny?
Hopefully not, unless your transfer switch also switches (& isolates) the neutral(s).

No I did not, but there is no transfer switch, so it does not matter even if I had. :cool2:

I just flip the main breaker when I am running on generator power.

 

[3Ts]

Talk about Project Creep...why not just upgrade your shop to 3 phase power while you are at it! (LOL)

I actually thought about it. For $1700 I could switch over to a 3 phase power unit. Go with single phase for the house, and 3 phase for the shop...

I looked into it too. It would have cost $48k just to bring it to the property. Then a little more to get it from there to the shop and all the electrical panel work. To tap into the existing single phase power was ~$1,300. I can have multiple single phase drops for that $48k. The limitation was a max of 26kw per single phase drop which is about 15 Hp electric motor after considering starting current load.

 

[BrokenTrack]

I looked into it too. It would have cost $48k just to bring it to the property. Then a little more to get it from there to the shop and all the electrical panel work. To tap into the existing single phase power was ~$1,300. I can have multiple single phase drops for that $48k. The limitation was a max of 26kw per single phase drop which is about 15 Hp electric motor after considering starting current load.

I was just going to hook a 27 kw, 3 phase generator up to my diesel engine, but a PTO, 27 KW, 3 phase generator is not a lot more at $2200.

That would save you about $46,000!! :dance1::cool2::drink:

 

[rbstern]

First of all, thanks gents, for the many contributions to the topic. Update:

I looked at the house blueprints, and realized the back wall in the closet of the mudroom was a reasonable route between the basement and the attic. Sure enough, I cut out a small section of sheet rock, and a couple of 1" holes later, I now have a workable cable path between the main panel and garage. I doubled up the roughtly 150' to 200' of 12/2 I had on hand and have so far run it from the closet to the panel. Tonight, I'll run it into the attic and through the breezeway roof to the garge. IF the line is long enough to give me two 12/2 circults, I'll set up one as 120V/20A, and the other as 240V/20A, and call it done. 4800 watts of oomph from the 240v feed should handle just about any welding I am likely to do (inverter/DC type welding), and if I had something it couldn't handle, I'll use my generator or take the work and the welder down to the basement workshop, where the panel is. The extra 120V circuit will handle an air compressor and any cutting/sanding machines I need. We're talking hobby grade stuff.

If the 12/2 line I have on hand isn't long enough for good outlet placement for both 120V and 240V outlets, I'll just use it for a single line 120V/20A, and hustle out to the local orange store and get either some 10/2 or 8/2 for the second line, with an appropriate breaker upgrade.

The subpanel is definitely attractive, but not essential.

Remind me I said that in a few years.

 

[3Ts]

I was just going to hook a 27 kw, 3 phase generator up to my diesel engine, but a PTO, 27 KW, 3 phase generator is not a lot more at $2200.

That would save you about $46,000!! :dance1::cool2::drink:

It needed to be on a timer with remote start/stop and was to run an irrigation pump. I wanted to go with a 40 hp stationary diesel engine to power the pump, but the folks that had the final say on it didn't believe a diesel could be set up that way. :mur:

Instead they wanted to go with a "written pole" motor which could provide up to 100 hp on the single phase line. However, they were unable to find a source (this was a few years ago) and no idea as to the cost. The techonology has been around for awhile to do it, but is normally used on major projects like hydro electric generators.
Ahead of the Curve: Written-Pole Electric Motors Provide 1 Horsepower Ratings on Single-Phase Utility Power | Farm Equipment

 

[rbstern]

Attic cable run is finished. I've got the two 12/2 wires in the garage. Was far less effort than I had myself convinced it would be.

Have to put in the receptacles and breakers, should be able to get that done this weekend. 240v power in the garage. Yipee!

Thanks again.

 

[dragoneggs]

Attic cable run is finished. I've got the two 12/2 wires in the garage. Was far less effort than I had myself convinced it would be.

Have to put in the receptacles and breakers, should be able to get that done this weekend. 240v power in the garage. Yipee!

Thanks again.

When I finally added a sub panel and added 3 220v circuits and was able to disconnect a long 220v homemade extension cord from a spare dryer outlet in the house I was dancing for joy. No more unplugging/plugging in a tool every time I wanted to use it. Also I can finally run the air compressor at the same time as the plasma cutter so I didn't have to take a break to recharge the tank while cutting! :thumbsup:

Having dedicated circuits in the garage/shop is liberating!

 

[sandman2234]

Having dedicated circuits in the garage/shop is liberating!

I completely understand! I went a different route, and pulled a separate address for my garage, then added a meter can with breakers(like a mobile home uses on a pole) and another 42 slot panel inside the garage. I now have 200 amp service in the garage and don't have to worry about the Bride firing up the stove while drying clothes when i am trying to weld!
David from jax

 

[BrokenTrack]

Having dedicated circuits in the garage/shop is liberating!

I kind of did the same thing.

I pulled a 100 amp circuit for my generator in my shop, but put in a dedicated 50 amp breaker for my welder, and a load box for several more.

My shop was already wired for 20 amp breakers every 4 feet, and lights of course, but I might just tie that into the new main 100 amp service now that there is plenty of room.

As you say; it is very liberating.

Not mentioned, and granted I have been accused of being scared of the dark on this, but I put lights up everywhere too. I think if every outside light was on in this house, shop and barn, I would light up 4 acres. But gosh darn it, outside in the winter: yeah I can see.