I’ve been tinkering with residential electrical work for about three years now—mostly small stuff like swapping out outlets, installing ceiling fans, and running a few new circuits in my basement. I decided to tackle a bigger project this month: replacing the old 100-amp panel in my 1960s house with a 200-amp service. My buddy who’s a licensed electrician walked me through the rough plan, but he’s been too swamped to help, so I’m doing it solo with his phone consultations. The main panel is in the garage, and the meter base is on the exterior wall just three feet away, so I figured it’d be straightforward.
I already pulled the permit from my local building department—took two tries because I forgot to include the load calculation sheet. I’ve got the new Siemens 200-amp main breaker panel, some 4/0 aluminum SEU cable, and all the grounding hardware. I’m working with a basic set of Klein tools, a decent torque wrench, and a Fluke multimeter I’ve had for years. The utility company came out and pulled the meter last Tuesday, so I’m sitting on dead wires right now. I’ve watched maybe a dozen YouTube videos, read through the 2020 NEC sections about service entrances, and even sketched out my bonding and grounding plan on graph paper.
Here’s where I keep second-guessing myself—and this is where the turning into a small junction box for the main panel feed comes into play. The existing conduit from the meter base runs straight into the garage wall, but it terminates in a little 4x4 box that was used for the old panel’s feed. I’m not sure if this matters, but that box feels undersized for the new 4/0 cable, and I’m worried about bending radius and physical clearance. I’ve considered just removing the box and running the SEU directly into the new panel, but the wall opening is too small for the panel’s knockout pattern without relocating it. My buddy mentioned I could use a gutter box or a larger pull box as an intermediate splice point, but then I’d need to keep the turning into a small junction box compliant with Table 312.6(A) for conductor fill and bending space. I’ve also thought about adding a disconnect outside to simplify the whole run, but that feels like adding cost and complexity I don’t need.
Forget the code book for a second—has anyone dealt with this situation where the existing conduit stub terminates in a crappy little box that just doesn’t work for modern wire sizes? Should I bite the bullet and patch up the drywall to mount the panel directly over the conduit entry, or is there a clever trick with a deep box that I’m missing? I’d love to hear what worked for you, especially if you’re in an older house with weird wall cavities.
I already pulled the permit from my local building department—took two tries because I forgot to include the load calculation sheet. I’ve got the new Siemens 200-amp main breaker panel, some 4/0 aluminum SEU cable, and all the grounding hardware. I’m working with a basic set of Klein tools, a decent torque wrench, and a Fluke multimeter I’ve had for years. The utility company came out and pulled the meter last Tuesday, so I’m sitting on dead wires right now. I’ve watched maybe a dozen YouTube videos, read through the 2020 NEC sections about service entrances, and even sketched out my bonding and grounding plan on graph paper.
Here’s where I keep second-guessing myself—and this is where the turning into a small junction box for the main panel feed comes into play. The existing conduit from the meter base runs straight into the garage wall, but it terminates in a little 4x4 box that was used for the old panel’s feed. I’m not sure if this matters, but that box feels undersized for the new 4/0 cable, and I’m worried about bending radius and physical clearance. I’ve considered just removing the box and running the SEU directly into the new panel, but the wall opening is too small for the panel’s knockout pattern without relocating it. My buddy mentioned I could use a gutter box or a larger pull box as an intermediate splice point, but then I’d need to keep the turning into a small junction box compliant with Table 312.6(A) for conductor fill and bending space. I’ve also thought about adding a disconnect outside to simplify the whole run, but that feels like adding cost and complexity I don’t need.
Forget the code book for a second—has anyone dealt with this situation where the existing conduit stub terminates in a crappy little box that just doesn’t work for modern wire sizes? Should I bite the bullet and patch up the drywall to mount the panel directly over the conduit entry, or is there a clever trick with a deep box that I’m missing? I’d love to hear what worked for you, especially if you’re in an older house with weird wall cavities.
