Unitized Distribution Substation (UDS) Installed Cost Comparison

Introduction

This document is a detailed economic comparison between the installed cost of VTI's Unitized Distribution Substation (UDS) and a system using separately mounted components for a typical 120 Volt lighting distribution system. This comparison study is based on the requirement for a 45 KVA, TP-1 Energy Efficient, 480 Volt to 120/208 Volt 3 phase transformer, a secondary main breaker, a 3 phase 4 wire 225 Amp panelboard and 42 - 1 pole, 20 Amp branch circuit breakers.

Installed Cost of VTI's UDS

VTI's UDS selected for this study is catalog number UDS MB45-3480-42 with 42 - 1 pole, 20 Amp plug-on branch circuit breakers.

Labor to Install UDS:

Drill 4 holes for anchor bolts (optional)	1.00 hour
Move UDS from staging area to location	1.00 hour
Set anchors and bolt down UDS (optional)	1.30 hours
Total field labor is 3.30 hours at a burdened rate of $51.83/hr

Installed cost of system using separately mounted components

For this study we used the following Bill of Materials and field labor estimates:

System Bill of Materials

Description	Discount Price
[*] Prices are based on the published Square D Company 2006 List Prices less the published electrical contractor trade discount schedule.
* 45 KVA Energy Efficient Transformer 3Ø 480 to 120/208 Cat 45T3HEE	$2,335.00
* Interior NQOD 442L225	838.91
* Box MH150S	11.90
* Front cover MHC50	117.32
* Main breaker kit NQOD 31150Q2MB	1038.54
* 42 branch circuits QO-120	863.32
3 - # 6 terminals T&B 54136	3.81
4 - # 1/0 terminal T&B 54109	14.68
1 - Ground lug T&B ADR25	2.91
40 ft. 1/0 THW cable	74.00
3 - 2" C-H LB 67	101.16
1 - 2" Erickson T&B 680AL	90.41
3 - 2" close nipples AL	62.10
1 - Engraved label for transformer	8.50
2 - 2" bushings TB-1227AL	46.26
4 - 2" lock nuts TB-146AL	15.08
8 feet of Unistrut	14.10
4 - spring nuts 3/8"-16 for Unistrut	2.08
4 - 3/8" bolts	0.28
4 - 3/8"" lock washers	0.16
1 - Engraved label for panelboard	8.50
1 - 6 ft. long 2"" conduit AL	24.66
1 - 2" x 2" conduit nipple AL	19.69
3 - LB covers C-H 670F	17.70
3 - Gaskets C-H GASK 476	9.93
4 - Wall anchors 3/8"	1.52
4 - Floor anchors 3/8"	1.52
Components, Material and Hardware Costs	$4,824.04

System Field Labor Estimates (in hours)

Locate/drill 4 holes in concrete to mount transformer	1.5
Locate/drill 4 holes in wall to mount panelboard	1.5
Cut 2 pieces Unistrut & Deburr	0.8
Drill 4 holes in Unistrut	0.5
Set anchors and bolt on Unistrut 2 pieces	0.5
Move transformer from staging area into place	2.50
Set anchors and bolt transformer down	1.5
Punch incoming and load KO's in transformer	0.75
Install 2 LB	1.0
Install 6 wire lug	0.8
Mount panelboard box	1.0
Punch incoming conduit hole	0.4
Install 2 LB close nipples and lock nuts and bushings	1.5
Cut and thread 1½" conduit	1.0
Assemble main lug panelboard & breaker adapter	1.75
Install Erickson nipple and conduit	0.5
Mount interior in box	0.4
Cut and install 4 pieces 1/0 cable	1.8
Install 3 LB's with covers and gaskets	0.5
Install 2 nameplates	0.5
Install 42 plug-in breakers	1.0
Punch-out trim	0.5
Install 42 lockout clips	0.75
Install trim	0.4
Install front cover	0.5
Install ground bar	0.5
Inspect/Megger transformer; cable to panelboard	2.0
Hours Total	26.35
Field labor estimate at a burdened rate of $51.83/hr.
Field Labor Cost	$1,365.72

Installation Cost Consideration:

According to field electrician reports, connecting the branch circuits on a panelboard with a 4.5"D x 5"W wire gutter takes about twice as long to make as in the UDS where you have 9.75"D x 9.5"W wire gutter. So with 126 connections to make (42 - 2 wire circuits plus ground), you have this additional cost to take into consideration:

Non-Tangible Costs:

Conclusion

One of the major benefits realized when using the UDS cabinet is its physical space savings. Comparing the physical space required, as seen in Figure 1, and by equating the differences to building costs, the dollar savings becomes significant when using the UDS cabinet. This additional space savings of $2,248.40 is calculated by using average pricing for floor and wall space in a typical ECR.

Therefore, the potential overall savings realized when using VTI's UDS is $2,658.00 which is the cumulative result of the $2,248.00 savings in physical space and the $410 savings in installation cost.

Note: These prices and times are based on extensive feedback information obtained from third party users. Your actual costs and field labor estimates may be different. However, in any evaluation it would be difficult to see that these differences would offset the overall total savings presented in this study.