Authors and distributors of:
proCALC software
for electrical engineers & contractors

BLR Technology ceased selling and distribution proCALC software in 2003 and since that time, have offered the software package as a Freeware download without any warranty, expressed or implied. Therefore, all use of the software is totally at the user's risk. The proCALC software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

From 1985 until 2003, proCALC electrical services software has been developed and distributed by BLR Technology Ltd and in that time, the package has been purchased by many leading services consultancy practices, local authorities and electrical contractors.

The package is now available as Freeware and may be obtained by following the 'Download' link on the left. Any potential users are required to accept the disclaimer and conditions of use. By downloading the software, the user is deemed to have accepted all such considerations.

proCALC  features include:

Works on any PC Windows/DOS based  computer with 5 megabytes of free disk space, together with any form of Text/VGA colour/monochrome monitor utilising 80 characters per column.

Extensive 'Help' screens at every data entry.

Very 'user friendly'

No limit to project size

All printouts on A4 paper

Complete design record of every cable or circuit assessment on one A4 printout

Simple self install facility; just follow screen instructions

Complete evaluation of main design considerations as one complete assessment

Design simple projects in less than 30 minutes

No loss of data on mains failure; all assessments immediately saved to disk

No computer knowledge required; you cannot press the 'wrong' key!

An extensive technical design takes place based on BS 7671 (formerly 17th Edition IEE Wiring Regulations), including the following:

Cable sizing from a large database

Choice of installation methods as BS 7671

Disconnection times evaluated from manufacturers' databases

Overload discrimination by electronic overlay of device characteristics

Overload device types & ratings selected from manufacturers' database

Parallel CPC facility for armoured cables

Up to 6 conductors may be assessed in parallel for both live and protective cables

Calculations based on design current, such as may be used for 'tails' assessments

'Current Project' facility which allows any number of projects to be designed concurrently

Selectable display showing cables sizing process to observe parameters causing cable sizing and recommendations that may reduce any unwanted conditions

Individual project selection of overall volt drop percentage (i.e. 2.5%, 4% etc.)

Design around Grouping problems

Define minimum conductor sizes when required

Earth fault loop, volt drop  and short circuit parameters carried through project

System modules:


Along with FINAL CIRCUITS, this module is the 'backbone' of the package, providing the facility to design all distribution cables, comprising 'tails', sub-distribution and submain assessments.

It is recommended that the Network Planner module is employed for each new project, with the projected values given being used as maxima within this program. The Network Planner will ensure that the all essential parameters are taken into account for whole installation , i.e. voltage drop, earth fault loop impedance, maximum system impedance, short circuit levels, diversity and discrimination between overload devices. Each distribution board submain will be projected in terms of the final circuit requirements supplied from the distribution board.

Generally, final circuits will not be designed with this module although the ability to set maximum
disconnection times and assess cables for maximum system impedance (Zs) are provided with this module.

A total of eighteen essential paramters are requested from the designer which may be revised at any time. Such changes incorporate the 'Auto Prompt' facility which automatically prompts revisions to other parameters that may or will inevitably be effected by the parameter selected for revision.

Additional submains, sub distribution services, etc., are designed by selection for the new schematic diagram facility which also monitors load distribution and power factor for each phase of every supply point for the installation.


The basic structure and method of operation is very similar to the DISTRIBUTION SYSTEMS module and reference to the previous section will provide a background to the module.

All final circuit applications should be designed with this module which, following the example of BS 7671, is based on overload devices of ratings up to 50A, although 60A and 63A MCBs are supported. In view of the overload device rating limits, cable sizes have a limit of 35 mm2.  Although rare, if a final circuit application exceeds these limits, the DISTRIBUTION SYSTEMS module may be used by setting the disconnection time to 0.4 or 5 seconds as required.

The values of System Impedance (Zs) are as those tabulated BS 7671 and major manufacturers but multiplied by a factor of Uo/230, where Uo is the phase to earth voltage declared in the appropriate 'Origin Parameters' module.

It is recommended that the Network Planner module is employed for each new project, with the projected values given being used as maxima within this program. The Network Planner will ensure that the all essential  parameters are taken into account for whole installation the whole installation, i.e. voltage drop, earth fault loop mpedance, maximum system impedance, short circuit levels, diversity and discrimination between overload devices. Each distribution board submain will be projected in terms of the final circuit requirements supplied from the distribution board.

The recent introduction of supply file selection from the installation scheamtic diagram and the new interface to allow designing and revising from a distribution board chart base has been well received by our customers.

Additional modules to the proCALC  basic package and included in this shareware version are:


This utility module displays the current project in the form of a Distribution Diagram, either on screen or by continuous printing on A4 paper. The project size is not a limiting factor as the screen will scroll to the project needs and the printout is vertically structured
to allow a continuous diagram. All essential design parameters are included on the printout.


Again designed as a utility module in that all printouts created from the main design modules may be  reproduced by this program. Consequently, the design information may be simply saved to disk and printed at a later time. This reduces design time by virtue of the computer memory not being tied up by the printer while the designer waits to commence the next assessment. In addition, backup hard copies of the complete design can be produced at any time. Additional facilities include:

Specification Schedules
As the title implies, design schedules may be printed for direct inclusion into a specification, for both Distribution Cables and Final Circuits.

Text Files
Following customer requests, this  facility was developed to allow the design information to be saved as basic text files in order that the information may be imported into a Word Processor, CAD or DTP package.

The information to be saved is selected by the user which, for certain items with lengthy descriptions, can be in an abridged or complete form.

Typical uses of this information are:

The creation of Distribution Board circuit charts

Importing design text into CAD drawings to utilise the information as a schedule or similar.

Distribution Board Circuit Charts
Installers may now print Circuit Charts from the design information and enter their description of the circuit use and areas served. This option also incorporates a Direct Entry facility to add or insert circuits that where not part of the original design.

Load Assessments
Detailed load assessments created with Distribution Systems and Final Circuits may be printed with this option.


This comprehensive module was developed in order that complete installations may be projected by employing standard factors for the complete installation. These 'standard factors' can be changed by a set up utility included with the program and include:

The extent of the network in terms of the maximum number of sub distribution cables and quantity of submains that may be fed from each subdistribution position, including the main intake (or installation commencement position).

The percentage of the entered design current to be added as a future growth factor (0% to50%).

An overall design factor employed to ALL cable assessments to take account of grouping, thermal insulation, ambient temperature, etc.

Halfsizing of conductor sizes (as an option) for cables with a length not greater that two metres.

Although the factors can be varied, the settings apply to the complete assessment which is therefore considered as a PROJECTION of the final design. With appropriate settings, the evaluated cable sizes will more often than not equate  to the subsequent full design values (via the Distribution Systems and Final Circuits modules) and would normally, as a worst case,  be within one cable size. Typical settings for  a cable factor  not greater than 0.75 and design current growth  between 10% to 20% would normally ensure  cables were not undersized in the
projection for most normal installation conditions.

Prior to using NETWORK PLANNER, the designer will benefit by producing a rough sketch of the proposed network as it is seen at concept stage by determining distribution positions, subdistribution and submain cables routes, estimated cable lengths and the projected loading from each service. In addition, the radius of operation within the building for each distribution board should be established. This is simply a worst case straightline measurement from the distribution board position to the extent of the area it serves. From this measurement, the module will interpret typical final circuit maximum lengths, which, in turn, will dictate the volt drop allowance (and therefore cable size) allowed on the associated subdistribution and/or submain cables in terms of the overall project volt drop constraint (e.g.2.5%, 4%) set on entering the program. This percentage, as with all other parameters, can be subsequently revised to review the effect on the complete installation, with a printout available (if required) to provide a hard copy of every revision.

This module has considerable benefits for users who are designers or installers.

For designers, the projected network, if undertaken at the commencement of the project, will avoid abortive designs arising from incomplete appreciation or inaccurate assumptions. Typical examples are:

Ensuring sufficient volt drop is available for final circuits

Designing the complete system such that overload device disconnection times are within prescribed limits by the monitoring of system  impedance (Zs) values for the respective devices. For example, distribution boards supplied from a network involving an  extended run may well find non compliance using type C MCBs unless parallel CPCs are employed. Such a potential problem will be identified by NETWORK PLANNER, therefore allowing the user to revise the supply cable type to find an acceptable solution.

For installers engaged in tendering on a 'design and install' basis, considerable overhead time can be lost in designing the project in order that costs can be evaluated. With NETWORK PLANNER, the installation can be projected within a short period of time from basic information sufficient to produce reasonably accurate costs. If the tender is accepted, the full design can be completed. With cable sizes within one size and generally not undersized with sensible default settings, the minor cost changes are acceptable in terms of the overhead saving if the tender is not accepted.

Among the general features are:

Complete projection of all installation design constraints for both distribution cables and final circuits.

Ability to vary any parameters and review the effect on the complete network.

Schematic diagram printout of all projected parameters with a schedule of the design parameters and values.

The facility to fix cable sizes and overload device ratings to project extensions or changes to existing installations.

Network schematic diagram displayed on screen with coloured phasing for clarity

Individual power factor facility

Neutral current calculations

Facility to select (and revise later if required) the network phasing for load balancing or phase continuity in an area

Various forms of wiring system

Parallel single core CPC facility for armoured cable systems.

Final circuit design parameters and maximum lengths projected from every distribution board.

Indication of the limiting factor of every final circuit projection giving the user the basis from which to revise the network on the supply side as necessary.


This module allows the design of lighting systems by employing the lumen method of calculation within a very flexible computer program. The photometric data despatched with the module comprises luminaires of many forms from a number of manufacturers which may be revised or extended. Any number of additional data files from manufacturers of their choice can be added by customers, the information being saved to disk for future use.

Lumen method emergency lighting calculations may also be undertaken with the module where the manufacturers photometric data for the luminaire includes 'zero' reflectances. Where this is not the case, this information can be added at any time. The general features include:

Screen displays and printouts of lighting layout approximately to scale

Selection of alternative luminaires for common design parameters

Printouts comprising design parameters and scaled layout on one A4 sheet

Revision of default parameters at any time

Comprehensive lamp database

Alternative lamp parameters can be included if not in database

Varying of any parameter and viewing of every change in assessment

Revision of recommended layouts  to view changes to design parameters (i.e. space/height ratios, Illumination levels, etc.)


The responsibility for ensuring an installation complies with BS 7671 (IEE Wiring Regulations) rests with both designer and installer for their respective areas of commitment. There is no demarcation line as such and in the testing of an installation the areas overlap.

In general terms, the installer is responsible for ensuring compliance with BS 7671 by testing the installation, but this can only be undertaken by means of the designer providing certain design information, i.e. cable maximum lengths and sizes, grouping constraints, earth fault loop and short circuit levels at the origin of the installation which form the basis of the design, etc.

We believe that the designer's responsibilities are fulfilled by the package as a whole with the use of Specification Schedules and Distribution Diagrams and part of the information provided to the installer. The designer's responsibilities do not end at this point, however, and there is a need to ensure that the installer has complied, as far as can be reasonably determined, with the
design. Typical measures are visual inspection of the works, witnessing testing and the evaluation of test certificates.

Witnessing the installer's testing for the COMPLETE installation is seldom practicable and the ability to accurately evaluate test certificates is therefore important. Even if all testing has been witnessed, the installer's certification requires checking as it will form part of the installation record.

To manually check and ensure the compliance of every circuit and system within an installation will consume considerable time. It is to minimise this time commitment and to undertake a technical verification that `Installation Testing' has been developed. In basic terms, the program produces two forms of test certificate, which are:

Blank certificates, or certificates printed with certain design information, on which the installer enters the installation test results.

On return of the completed test certificates from the installer, the designer may then use this module and the project in question to enter the installer's ACTUAL cable lengths and obtain an accurate printout (in similar form) for comparison with the installer's certificates.

Test certificates comprising all site test results can be obtained to avoid using typewriters and word processors for the task. Design information is recalled automatically and the user simply enters the site information as prompted. As with all other facilities in this module, the Direct Entry of Parameters allows circuits that did not form part of the original design to be added of inserted into the test certificates. In addition, the Direct Entry method allows certificates to be produced for projects that were not designed with the package.

Alternatively, the design cable lengths may be employed to obtain the 'worst case' affording compliance, thereby saving the time taken to enter the installer's lengths.

Module features include:

Accurate assessments of installed circuits based on ambient temperature at the time of testing and recorded earth fault loop impedance values at the supply point

Utilisation of data from projects designed with the package or direct entry of data for installations not designed with the software

Printing blank certificate sets (with customer's name) for use by site operatives engaged in testing

Printing Project Test Certificate sets that provide test sheets for site operatives which include all design information

Provision of screen display and printouts of theoretical circuit/system values based on installed length of design maximum lengths

Projection of bands in which earth fault loop impedance values will fall with all bonding connected (i.e. as on completion of project)

Separate entry of lengths for live and protective conductors if required

Radial/ring circuits parallel conductors supported

On completion, a full testing record of every circuit/submain in an installation is provided

Site Test Certificates
Test certificates for all site test results can be obtained from the module thus avoiding the use of typewriters and word processors. Design information is recalled automatically and the user simply enters the site information as prompted. As with all other facilities in this module, the Direct Entry of Parameters allows circuits that did not form part of the original design to be added of inserted into the test certificates. In addition, the Direct Entry method allows certificates to be produced for projects that were not designed with the package.


Point source illumination assessments are provided for ceiling and wall mounted applications, giving values for positions directly below luminaires, axial and transverse midpoints, ends of rows and corners.

In addition, average illumination is calculated (by lumen method for ceiling mounted applications) and vertical illumination at 2.2m height for the illumination of fixed signage on escape routes.

The module assumes the use of self contained emergency equipment that may or may not be integral with a general lighting luminaire. As spacing of the latter is normally fixed by the general lighting layout, the program allows spacing and dimensions off end walls to be entered in order that the emergency design will align with the general lighting layout.

The database is not one of manufacturer's luminaires but comprises diffusers, louvres, reflectors, etc. in common use. Consequently, the database need not be extended for particular manufacturers as the photometric data for specific types of diffuser, etc. is very similar.

General lighting calculations on a similar basis can also be undertaken to complete a full lighting design for interior applications.


The user is recommended to select the DEMONSTRATION project and use PRINTING OPTIONS with NETWORK PLANNER PRINTOUT to obtain typical printouts issued by the package. Creation of the user's own test project will also allow printouts at the appropriate stages.

Copyright BLR Technology Limited, January 2005

All BLR Technology products are trademarks or registered trademarks of BLR Technology Limited. All other brand and product names are trademarks or registered trademarks of their respective holders.

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BLR Technology Ltd.