kumasan
Member
- Location
- Northern California
- Occupation
- Electrical Engineer
Hello, and thank you for all the great information in the forums.
Im in the process of upgrading my system to add some more panels.
My generation demand pushed me beyond my capacity of my 200A main panel with the 120% rule, and required me to purchase a larger subpanel to handle the bus loading.
Im planning on using a 400 Amp siemens MLO subpanel W0606ML1400CU. It is about 100LB without any wire/breakers. I plan on mounting it to my stucco wall. The wall consists of ~1" thick stucco over tar paper and 2x4 studs (no plywood).
My local jurisdiction requires me to have a formal CAD drawing of the mounting arrangements for any panels > 100lbs so Im trying to be super careful to do it compliant to any codes.
Unlike the typical 200A subpanels this unit does not have recessed mounting holes to offset the panel slightly from the house. It does have 4 large 5/16 bolts with heads sticking out the back side of the unit. The bolts go through to the inside of the cabinet and mount the central panel busbar assembly with some nuts on the inside. The bolts appear to be extra long, possibly to allow attachment to superstrut or something similar on the back side.
There are also 4 what appear to be possible mounting holes that are flush with the back of the panel and #12 size (slightly less than needed for 1/4" bolts)
The reason I say mounting holes is that they are larger than the holes for mounting ground bars and placed in the upper and lower areas where you would expect mounts. Although Im not sure about the robustness of 4x #12 screws
With the 200A panels I usually use the center hanger and tap into a stud with a deep lag bolt, then stucco anchors on 4 corners using the offset mounting holes.
For this panel I am a little uncertain what is the usual way to mount to stucco. Here are some possible ways I was thinking.
a) Use #12 x 3" screws into a stud on one side and #12 screws into stucco anchors on the other using existing #12 holes.
b) Same as a) but enlarge the holes to support 1/4" or larger lag bolts.
c) New holes aligned with 16" oc studs on both sides and lag bolts. The box is ~20 inches wide so I could drill new holes and have two bolts on each side into studs. Then use some good silicon around the bolts, or another NEC compliant method.
For all of the above since the bolt head and washer stick out ~3/8" on the back, I would either need to use offset washers/spacers about the same thickness as the bolt head, or drill reliefs cut in the stucco where the bolts poke out.
d) Horizontal superstrut straps, attached to studs with lag bolts. and then attached to the back of the box. They make some < 1" thick superstrut that does not stick out too far, but I would need to do something to make it wider so that the heads of lag bolts into the studs dont interfere with the back of the panel.
I would appreciate any suggestions on a robust way to attach the panel.
Thanks,
Paul
Im in the process of upgrading my system to add some more panels.
My generation demand pushed me beyond my capacity of my 200A main panel with the 120% rule, and required me to purchase a larger subpanel to handle the bus loading.
Im planning on using a 400 Amp siemens MLO subpanel W0606ML1400CU. It is about 100LB without any wire/breakers. I plan on mounting it to my stucco wall. The wall consists of ~1" thick stucco over tar paper and 2x4 studs (no plywood).
My local jurisdiction requires me to have a formal CAD drawing of the mounting arrangements for any panels > 100lbs so Im trying to be super careful to do it compliant to any codes.
Unlike the typical 200A subpanels this unit does not have recessed mounting holes to offset the panel slightly from the house. It does have 4 large 5/16 bolts with heads sticking out the back side of the unit. The bolts go through to the inside of the cabinet and mount the central panel busbar assembly with some nuts on the inside. The bolts appear to be extra long, possibly to allow attachment to superstrut or something similar on the back side.
There are also 4 what appear to be possible mounting holes that are flush with the back of the panel and #12 size (slightly less than needed for 1/4" bolts)
The reason I say mounting holes is that they are larger than the holes for mounting ground bars and placed in the upper and lower areas where you would expect mounts. Although Im not sure about the robustness of 4x #12 screws
With the 200A panels I usually use the center hanger and tap into a stud with a deep lag bolt, then stucco anchors on 4 corners using the offset mounting holes.
For this panel I am a little uncertain what is the usual way to mount to stucco. Here are some possible ways I was thinking.
a) Use #12 x 3" screws into a stud on one side and #12 screws into stucco anchors on the other using existing #12 holes.
b) Same as a) but enlarge the holes to support 1/4" or larger lag bolts.
c) New holes aligned with 16" oc studs on both sides and lag bolts. The box is ~20 inches wide so I could drill new holes and have two bolts on each side into studs. Then use some good silicon around the bolts, or another NEC compliant method.
For all of the above since the bolt head and washer stick out ~3/8" on the back, I would either need to use offset washers/spacers about the same thickness as the bolt head, or drill reliefs cut in the stucco where the bolts poke out.
d) Horizontal superstrut straps, attached to studs with lag bolts. and then attached to the back of the box. They make some < 1" thick superstrut that does not stick out too far, but I would need to do something to make it wider so that the heads of lag bolts into the studs dont interfere with the back of the panel.
I would appreciate any suggestions on a robust way to attach the panel.
Thanks,
Paul