Power connections
Busbar Insulation: Epoxy Powder after Fabrication, or Raychem BBIT
Use Storm epoxy after the bar is bent and punched. Use TE Raychem BBIT when the sheet's 36 kV flashover rating and the 11 mm to 125 mm size range match the bar.
On this page
Use Storm epoxy powder when the insulation goes on after bending, punching, and milling. On the Storm design guide, opened October 22, 2026, inverter and low-voltage switchgear point to electrostatic spray, and medium voltage points to a fluidized bed. A high-voltage bar on that guide should be fluid dipped to a thickness greater than 0.12 inch. The guide prints about 800 volts per mil at a minimum of 10 mils, a coating thickness from 6 mil to 120 mil, a thermal UL rating of 130°C, and a coating tensile strength in the range of 7,500 psi. Use TE Raychem BBIT when the bar is round or rectangular copper or aluminum and the requirement is flashover protection up to 36 kV. Data sheet EPP-0607, opened the same day, covers application diameters from 11 mm to 125 mm and prints a recovered wall minimum of 3.6 mm on each size row, with thermal endurance of 125°C minimum.
Epoxy goes on after the bar is formed
Storm's guide says epoxy powder is applied after bending, contouring, punching, and milling, so the coating is not asked to stretch around a bend made later. The guide contrasts that sequence with cable or pre-insulated busbar that is bent after the insulation is already on. Electrostatic spray is the method the guide assigns to inverter applications and to low-voltage switchgear. Fluidized bed is the method it assigns to medium voltage, to complicated shapes, and to a high-voltage bar that needs a thickness greater than 0.12 inch. The guide also says the process can apply thicknesses up to 100 mil or more, and that the coating range is 6 mil to 120 mil. Those thickness lines are Storm's. BBIT wall thickness is the recovered-wall column on EPP-0607.
The dielectric line in the Storm guide is about 800 volts per mil at a minimum of 10 mils. The same guide says the insulation is used in medium- and high-voltage applications up to 35,000 volts. It also says to high-potential test the finished part rather than rely on film thickness alone, and it states that Storm's high-potential testing follows section 6.2.1 of ANSI/IEEE C37.20.2-1999. Dimension the drawing to the copper, not to the powder surface. The guide suggests a masking tolerance of plus or minus 0.0625 inch. Colors listed are blue, gray, red, green, brown, pink, and black.
BBIT is the 36 kV tube, on a listing that also shows other classes
EPP-0607 titles BBIT as voltage class 36 kV, for application diameters 11 mm to 125 mm, on circular and rectangular copper or aluminum busbars. The sheet says the tubing provides flashover protection up to 36 kV. On the TE family listing opened the same day, BBIT catalog rows are marked 36 kV or below, including 197127-000 (BBIT-65/25-A/U(B50)) and 108727-000 (BBIT-175/80-A/U-(B50)). BPTM rows on that listing are marked 25 kV or below, including 024331-000 (BPTM-75/30-A/U(B50)). The overview sentence on the same listing says this tubing group provides protection up to 72 kV, and it names BBIT, BPTM, and HTIT in that sentence. For a BBIT part, use 36 kV from EPP-0607 and from the BBIT row. The clearance table below is the BBIT sheet. BPTM clearances stay on a BPTM sheet.
EPP-0607 prints thermal endurance of 125°C minimum to IEC 216, and low-temperature flexibility with no cracking after 4 hours at -40°C. Dielectric strength on that sheet is 350 kV/cm minimum at 1.00 mm, also printed as 889 V/mil minimum at 0.04 inch. Further lines on the same table are 180 kV/cm minimum at 2.00 mm (450 V/mil minimum at 0.08 inch), 150 kV/cm minimum at 2.50 mm (381 V/mil minimum at 0.10 inch), and 120 kV/cm at 3.00 mm (304.80 V/mil at 0.12 inch). Storm's about 800 volts per mil is a different sentence, tied to a 10 mil minimum. Keep each volts-per-mil figure with the thickness printed beside it.
Clearances the BBIT sheet prints
EPP-0607 prints separate clearance tables for round and rectangular busbars, derived from BIL, AC withstand, DC withstand, and discharge-extinction tests. The sheet says these clearances should not be adopted without testing by the user, and that sharp electrodes and unusual geometries may require wider clearances. IEC 71-2 air clearance is the right-hand column on both tables. Storm's guide does not print this millimeter grid.
| Bar | Rated voltage | Phase to phase | Phase to ground | IEC 71-2 air clearance |
|---|---|---|---|---|
| Round | 12 kV | 30 mm (1.18 in) | 40 mm (1.57 in) | 120 mm (4.72 in) |
| Round | 17.5 kV | 45 mm (1.77 in) | 60 mm (2.36 in) | 160 mm (6.30 in) |
| Round | 24 kV | 60 mm (2.36 in) | 90 mm (3.54 in) | 220 mm (8.66 in) |
| Round | 36 kV | 100 mm (3.93 in) | 160 mm (6.30 in) | 320 mm (12.60 in) |
| Rectangular | 12 kV | 35 mm (1.38 in) | 45 mm (1.77 in) | 120 mm (4.72 in) |
| Rectangular | 17.5 kV | 55 mm (2.17 in) | 65 mm (2.56 in) | 160 mm (6.30 in) |
| Rectangular | 24 kV | 70 mm (2.76 in) | 100 mm (3.93 in) | 220 mm (8.66 in) |
| Rectangular | 36 kV | 140 mm (5.51 in) | 190 mm (7.48 in) | 320 mm (12.60 in) |
Which BBIT size covers the bar
The selection table on EPP-0607, as of October 22, 2026, uses rectangular L plus T, round diameter, supplied inside diameter, and recovered inside diameter. Recovered wall minimum on each of these rows is 3.6 mm. Supplied wall nominal on each row is 1.6 mm. The sheet says to fit the larger size if two sizes fit the bar. Maximum longitudinal change after free recovery is plus or minus 5 percent. Maximum eccentricity as supplied is 35 percent.
| Ordering description | Rectangular L+T | Round diameter | Inside diameter supplied to recovered |
|---|---|---|---|
| BBIT-25/10-A/U-4 | 17 mm to 28 mm | 11 mm to 20 mm | 25 mm to 10 mm |
| BBIT-40/16-A/U-4 | 28 mm to 45 mm | 18 mm to 32 mm | 40 mm to 16 mm |
| BBIT-65/25-A/U-4 | 44 mm to 69 mm | 28 mm to 47 mm | 65 mm to 25 mm |
| BBIT-100/40-A/U-4 | 69 mm to 102 mm | 44 mm to 72 mm | 100 mm to 40 mm |
| BBIT-150/60-A/U-4 | 102 mm to 148 mm | 65 mm to 105 mm | 150 mm to 60 mm |
| BBIT-175/80-A/U-4 | 133 mm to 196 mm | 85 mm to 125 mm | 175 mm to 80 mm |
A plated contact face is a different instruction from either coating. The tin and silver finish page is the joint surface. Epoxy or BBIT on that face is insulation over the joint, which the drawing has to allow.
What to name before the insulation quote
- Formed bar or straight bar. Storm's powder is applied after bending, punching, and milling.
- Voltage class. Spray or fluid bed comes from Storm's inverter, low-voltage, and medium-voltage lines. BBIT is the 36 kV sheet.
- Thickness or recovered wall. Storm's range is 6 mil to 120 mil, with fluid dip above 0.12 inch for the high-voltage case. BBIT's recovered wall minimum on the size table is 3.6 mm.
- Bar size in millimeters, matched to one BBIT ordering description if the tube is BBIT.
- Clearance the design uses, from the round or rectangular table, plus the test the user still runs.
- Masked or bolted faces that must stay free of powder or tubing.
Questions the two insulation pages answer
Can the tube be shrunk and then bent with the bar?
Storm's guide is about coating after the bends exist, because bending a pre-insulated bar loads the insulation. BBIT is heat-shrink applied to the busbar profile. The BBIT sheet does not say the bar may be bent after the tube is recovered. Form the bar first, then choose powder or tube.
Is 800 volts per mil the same rating as 889 volts per mil?
Storm prints about 800 volts per mil at a minimum of 10 mils. EPP-0607 prints 889 V/mil minimum at 1.00 mm, which is one line in a table that changes with thickness. Keep each figure with its thickness.
Does the family page's 72 kV line replace the BBIT sheet?
The family overview names BBIT, BPTM, and HTIT in one sentence at up to 72 kV. The BBIT rows on that listing, and EPP-0607, say 36 kV. Order BBIT against the 36 kV sheet. Use a different series row when the listing's voltage mark is 25 kV or the group line is the one the drawing cites.
Sources
Process sequence, spray and fluid-bed assignments, thickness, the 800 volt-per-mil line, 130°C, 7,500 psi, the 35,000 volt sentence, and the masking tolerance are from Storm's epoxy design guide. Voltage class, wall, thermal endurance, dielectric lines, clearances, and size rows are from TE data sheet EPP-0607. The 25 kV, 36 kV, and 72 kV listing marks are from the TE family page. All three were opened October 22, 2026.