Engineering & electrical design · Holliday Process Solutions
Holliday Process Solutions
Engineering & electrical design

Designed by engineers. Checked by the engine. Built to UL 508A.

Every HPS panel starts as a drawing that has already been calculated: loads, conductors, voltage drop, short-circuit rating, heat, clearances and grounding. Our electrical and mechanical engineers lay it out, and the HPS design engine checks every change against the standard before a wire is cut. Watch one panel go from specification to a released drawing set and 3D model.

Send us a specification What gets checked
HPS · RICHLAND HILLS, TXCONTROL PANEL LAYOUT · RTU-101DWG E-201SHEET 3 / 14REVAUL 508A1:4HPS DESIGN ENGINE · OPENING E-201 CONTROL PANEL LAYOUT_30.00 in24.00 inNEMA 4X · 316 SS30 × 24 × 10DIN RAIL 1DIN RAIL 2DIN RAIL 3DS1480V DISCCB120ACB210ACB35APS124 VDC 10 ASPD1SPDPLC1CPUIO1DI 16IO2DI 16IO3DO 16IO4AI 8SW1ETH 8PCR1CR2CR3CR4CR5CR6FU1–6TB1 · 1–22TB2 · 1–22GROUND BAR · PEL1L2+24V+24V101201DI-01PEVFD15 HP · 480 VFAN1 · 105 CFMEXHAUST30AAABBCCDDEEFFGGHH112233445566HOLLIDAY PROCESS SOLUTIONS · RICHLAND HILLSPOWER DISTRIBUTION ONE-LINEPROJECT RTU-101 · CONTROL PANEL · UL 508ADRAWN JMH · CHK ERG · APPR HPS ENGDWGE-101SHEET1 OF 14REVBDATE09-22-26REV DESCRIPTION BY DATEA ISSUED FOR REVIEW JMH 09-15-26B CO-1 ADD VFD1 5 HP · CB1 30 A · FAN1 JMH 09-22-26FROM MCC-1 · 480 V 3Ø 60 Hz · 30 A · AIC 65 kA3 × 10 AWG THHN + 10 AWG GND · 1 in RGSDS130 A · NON-FUSED DISCONNECTFU1-330 A · CCSPD1UL 1449 TYPE 2PANEL BUS · 480 V 3Ø · SCCR 65 kACB130 A · 3P · REV BVFD15 HP · 480 VREV B · CO-13 × 12 AWG VFD CABLE + SHIELDMM1 · 5 HP · 7.6 FLACB210 A · 2PCPT1480 / 120 V · 500 VAFU45 AX1120 VAC CONTROL → E-301X2CB35 A · 2PPS1480 VAC → 24 VDC 10 A+24V0VDC BUS → E-302GROUND BAR · PE · 4 AWG TO BUILDING GROUNDNOTES1. SCCR 65 kA PER UL 508A SB4 WITH CLASS CC CURRENT-LIMITING FUSES.2. CONDUCTORS MTW 90 °C, SIZED AT 125 % CONTINUOUS PER NEC 310.16.3. WIRE COLORS PER UL 508A 66.9: BLK 480 V · RED 120 V · BLU 24 VDC WHT/BLU DC COM · GRN/YEL PE.4. VOLTAGE DROP FEEDER 0.1 %, BRANCH MAX 0.5 %.5. NAMEPLATE: 480 V 3Ø · 30 A · SCCR 65 kA · TYPE 4X · UL 508A.6. REV B: CO-1 ADDS VFD1, CB1 30 A, FAN1 105 CFM, EXHAUST VENT.AABBCCDDEEFFGGHH112233445566HOLLIDAY PROCESS SOLUTIONS · RICHLAND HILLSCONTROL SCHEMATIC · 120 VAC / 24 VDCPROJECT RTU-101 · CONTROL PANEL · UL 508ADRAWN JMH · CHK ERG · APPR HPS ENGDWGE-301SHEET5 OF 14REVBDATE09-22-26REV DESCRIPTION BY DATEA ISSUED FOR REVIEW JMH 09-15-26B CO-1 ADD VFD1 5 HP · CB1 30 A · FAN1 JMH 09-22-26X1 · 120 VACX2101PB1 E-STOP1011PB2 E-STOP1012SS1 RUN1013MCR102,103,110102MCR1011021PL1CONTROL ON103MCR1011031FU52 AX1A→ PLC1 / SW1 POWER (E-302)104LS1 HI LVL1041TB1-3IO1 · I:0/01003X2105PS2 LO PRES1051TB1-5IO1 · I:0/11005X2106ZS1 DOOR1061TB1-7IO1 · I:0/21007X2107VFD1 FAULT1071TB1-9IO2 · I:1/01009X2108IO3 · O:0/02001CR1109109CR11081091TB2-1SOL1 · FIELD 120 V2003110MCR1011101IO3 · O:0/12005CR3111111CR31101111TB2-5VFD1 RUN · DI12007112FTFT1 4–20 mA3001/3002TB1-15IO4 · AI 0+ / 0−3001X2NOTES1. 24 VDC +24V / 0V FROM PS1 (E-101); PLC1, SW1, IO1–IO4 POWER FUSED PER MODULE FU6–FU9 2 A (E-302).2. SHIELDS DRAIN TO PE AT PANEL END ONLY. ANALOG PAIRS 18 AWG TWISTED SHIELDED, SEGREGATED FROM 120 V DUCT.3. WIRE NUMBERS = LINE NO. + SEQUENCE. RED = CROSS-REF.DESIGN RELEASED · REV B · 14-SHEET DRAWING SET · UL 508A CHECKLIST 42 / 42 · 3D MODEL AT RIGHT
HPS DESIGN ENGINE · EXAMPLE JOB RTU-101STEP 0 / 10
3D model · RTU-101

The same panel, built in three dimensions as the drawing is checked.

Rotate, zoom and look inside. Hide the enclosure or the backplane to inspect the components on their own. The model is generated from the same layout data as the drawing above, so what you see is what the shop builds.

3D MODEL · RTU-101
drag to rotate · scroll / pinch to zoom · right-drag to pan · double-click to reset
What the engine checks

The formulas behind every HPS drawing.

None of this is new to a good panel engineer. What is new is that every one of these checks runs again, automatically, each time a component is added, moved or resized, so a change order never ships an undersized conductor or an overheated enclosure.

Load & conductor sizingI = P / (√3 · V · PF)Icont = 1.25 · I

Loads summed per branch, continuous loads at 125 %, conductors from NEC 310.16 with temperature and bundling corrections, breakers to the next standard frame.

Voltage dropVd = 2 · K · I · L / CM

Every run from the disconnect to the last field terminal, held under 3 % on branches and 5 % feeder-to-load, with the copper constant K corrected for conductor temperature.

Short-circuit current ratingSCCR = min(component ratings) per UL 508A SB4

The weakest device sets the panel rating. The engine finds it and proposes current-limiting fuses or series-rated combinations until the nameplate meets the owner's available fault current.

Heat load & coolingΔT = ΣPloss / (k · A)CFM = ΣPloss · 1.8 / ΔT

Component losses summed from datasheets, enclosure surface area from the model, solar gain for outdoor Texas. Passive if it can be, fan or air conditioner sized when it cannot.

Clearances & creepageUL 508A Table 10.1 · spacings by voltage

Through-air and over-surface spacings between live parts, grounded metal and the enclosure, plus door swing, duct fill and bend radius for the technician who has to service it.

Grounding & bondingUL 508A 15 · NEC 250 · IEEE 142

Equipment grounding conductor sized to the largest overcurrent device, bonding of the door, backplane and shields, and the surge protection coordinated with the ground.

Electrical and mechanical

Two disciplines, one drawing set.

A control panel is an electrical device inside a mechanical one. HPS engineers both, so the enclosure, the thermal design, the mounting and the wiring are decided together instead of handed across a wall.

ELECTRICAL

Power, control and protection

  • Single-lines, schematics and wiring diagrams
  • Conductor, breaker and fuse selection
  • SCCR, arc-flash inputs and coordination
  • PLC / RTU I/O design and network architecture
  • Surge, grounding and lightning protection
MECHANICAL

Enclosure, thermal and structure

  • Enclosure sizing, NEMA type and material
  • Heat-load calculation, fans, heaters and A/C
  • Skid, pole and wall mounting with load calcs
  • Cable entry, gland plates and conduit layout
  • Vibration, wind and solar exposure for site
STANDARDS

Built to the listing, not near it

  • UL 508A industrial control panels
  • UL 1203 / UL 12.12.01 for classified areas
  • NFPA 79, NFPA 70 and 70E practices
  • ISA-5.1 tagging and owner standards
  • Factory acceptance test on every panel
DELIVERABLES

What you receive

  • 2D drawing set in AutoCAD: layout, schematics, wiring, BOM, nameplate
  • 3D model and rendering for review and mounting
  • Calculation package: loads, voltage drop, SCCR, thermal
  • Point-to-point checklist and FAT record
  • As-builts revised after commissioning
UL 508AUL 1203UL 12.12.01NFPA 79NEC · NFPA 70EISA-5.1AUTOCAD ELECTRICAL3D · STEP
From the shop floor

The drawings become these.

Panels HPS engineered and built to the process above, from the HPS shop.

Wired RTU control panel with redundant controllers
RTU panel

Redundant controllers, marshalled I/O

Segregated power, control and signal ducts exactly as the layout drawing shows them.

PLC rack panel
PLC panel

PLC rack with local I/O

Breakers, terminals and rails placed for service access and thermal spread.

DIN rail power distribution
Power distribution

Protected DC distribution

Surge protection and fusing sized from the same load calculation.

Control panel under construction in the HPS shop
In the shop

Built from the released set

Every wire number on the panel matches the schematic sheet it came from.

Start with the spec

Send us the I/O list and the site conditions.

We return a layout, a calculation package and a price. If you have an owner's standard or a template drawing, send that too and we build to it.

Talk to an engineer