Split Meter Electrical Service Plan
Challenge: Run two 100A panels from one meter base without using a subpanel.
Existing overhead service from CEA to house and 100A panel. We want upgrade our service to 200A, add power to the new garage, but not replace/disturb the existing house panel. We wish to use a "split" service configuration and avoid a main & subpanel situation if at all possible.
New garage needs power. Since garage is located closer to the service drop pole than the house, it makes sense to swing the drop over to the garage. This would mean installing a new meter base, a new mast, new ground rods, a new panel in the garage, digging a trench, and running underground conduit and service line back to existing house panel. By this configuration, each panel would be fed by separate conductors from a single 200A meter socket. Old mast and meter at house will be removed.
Concept sketch. I think this is the way a split service meter should look, but not I'm not 100% sure how a the load-side lugs are configured inside the meter box. I think this is called a "dual lug" or "split meter main" and comes with two 100A breakers integrated into the load side of the box (not shown in sketch). Grounding and bonding details are left out.
Filling in more details. Things not shown include some details inside meter box, wire routing/connections inside house, and point of connection strap on mast. I may also need a #6 ground wire alongside the buried USE-2 line.
EATON Cutler-Hammer Series #MBE24L200BTS
Type BR, 10 kAIC, 3 wire, single phase, 4 jaw, 200A, surface mount, ring type, overhead/underground outdoor meter breaker w/ 4 spaces & 8 circuits. Dimensions: 28.38"h x 14.44"w x 5.38"d. EUSERC rated.
This "dual-lug" Cutler-Hammer meter main accommodates 2 sets of load-side conductors (service for 2 separate panels) via two 100A breakers that fill the four knockouts. Breakers are purchase separately. Left side is line side (power company), right side is load side (customer). 3-wire service line enters the box at top left (add hub, 2" steel mast, and weatherhead). Line to garage panel exits out the back (through wall). Service to the house panel drops out at bottom right via 2" Liquid Tight conduit to trench.
100A Breakers for Meter
EATON Type BR2100 Type C2100 Cu/Al HACR Type 2-pole J969 120/240V~ E7819-T LR43556 Disj.
Wire Run A: Meter to Weatherhead
3 separate conductors (~12' run)
SuperSlick Elite 7-stranded copper
2 AWG Type XHHW-2 OR RW90 GR2 Sun-RES VW1 FT1 600V XLPE (UL) OR C (UL)
Wire Run B: Meter to Garage Panel
3 separate conductors (<24" run)
W 2 AWG AL XLPE 600V USE-2 SUN-RES (UL)
Wire Run C: Meter to House Panel
3 conductors (~65' underground run)
W 2 AWG AL XLPE 600V USE-2 SUN-RES (UL)
Wire Run D: Grounding
Stranded 6 AWG in green jacket (just like Tiger) run in 1/2" PVC to burial-rated clamps on 2 ground rods (5/8" x 8') set flush with finished grade 8' apart.
- Garage panel to meter (<24") = 1" flexible metal conduit run inside 2x6 wall studs; ground bushing at meter.
- Riser from meter to trench = 2" Liquid Tight.
- Buried portion of URD cable not in conduit.
- Riser from trench to house entry box = 2" Liquid Tight.
- Ground wire from meter to ground rods = 1/2" PVC.
- What modifications are needed at house (exterior and interior) to bring new line to existing panel?
- Is there any issue in running URD in a trench at 24" depth under the driveway (gravel)? Driveway is within 6-12" of finished grade, but final grading/addition of fill still to be done. Trench is dug and is 24" now; will be almost a foot deeper when finished grade is achieved.
- Does existing grounding system at house (to water pipe? ground rods?) need to be connected to new rods at garage or can each building be grounded separately?
- One ground bushing or two? One for sure at exit out back of the meter box, but do I need another one at the entry to the garage panel?
- Is additional grounding wire needed anywhere?
Advice on Buying Electrical Equipment from a Skilled DIY-er
The big box stores are terrible places to buy anything electrical. Find the best local supply house in your town and ask them to help you. The best local place in my town is Brown's Electrical Supply Company. I had never been in before. I took with me some sketches (the first 3 shown here) and explained what I wanted to do to the best of my knowledge. They asked a few questions, corrected some of my misconceptions, and got me what I needed in about 20 minutes. I didn't have to hunt and peck for anything. They gave me a recommendation on a good local electrician that does small projects like mine and helped me load my car. I paid less than I would have at Brown's than I would have at Amazon, HD, or Lowes. More importantly, I didn't have to wonder if the stuff I was buying was the right stuff. If you haven't noticed already, electricians use a ridiculous amount of jargon. Terms for parts and wire differs from region to region, which makes research online difficult. The basics are often shrouded in mystery. Manufacturer catalogs are cryptic. Online discussion boards tend not to produce answers. Books are sort of helpful, but are always incomplete. The right answer is go to the local supply house counter or have an electrician handle all of it. In the end, I spent between $600-700 on this project by going through an electrical supply house. It saved me time and a lot of headaches.
This double-lug configuration seems to be close to what we're after but for 200A meter, not 400A as shown here. Source: https://www.duke-energy.com/pdfs/Parallel_Main_Panels_from_a_Single_Meter_Base.pdf
Draft #1. My initial design notes put into a sketch.
Helpful Information Online
Electrical Wiring Abbreviations
Definitions of Household Wiring Terms
Electrical Symbols Used in Technical Drawings