A steel support can carry services at normal temperature and still deform or lose strength when heated. For the contractor or specifier, the question is whether the actual bracket, frame, connections and building attachment have been assessed for the required fire condition.
The support is a structural assembly. Its section, geometry, connections and attachment all affect how it carries pipework or cable containment. If one part changes during coordination, the load path and the evidence may change with it.
Steel loses strength as it heats. Its strength diminishes significantly at around 500°C and falls to 4% of its original strength after 90 minutes. As strength falls, rigidity and loadbearing capacity also reduce, and members deform. These figures describe steel behaviour. They are not a rating for every steel section or support.
The temperature reached by a support depends on the fire exposure and the way the member is arranged. The steel section, its connections and how it is attached also matter to the design. A single temperature or strength figure cannot describe the performance of a whole support.
The design question is not simply whether the bracket or channel is steel. Check whether the support type and its connections have been assessed for the fire condition and service requirement on the project. The calculation or test evidence should describe the installation being specified.
Strut channel is thin-walled and open-sided. Its shape and its channel-nut connections differ from many traditional structural steel sections. EN 1993-1-2 provides an analytical route for structural steel in fire, but the technical information for channel supports identifies a limit to using calculations alone.
Fire-test observations for channel track Eurocode predictions up to approximately 700°C. Above that level, measured deformation and, in some cases, buckling can exceed the calculations. For channel-based supports, EN 1993-1-2 is considered valid up to around 600°C. Above that boundary, calculations alone are unreliable.
The standard time-temperature curve exceeds 600°C in just 6 minutes and reaches 842°C at 30 minutes. These figures put the calculation boundary in context. They do not predict the temperature of every installed support, because its exposure and position affect the result.
Use the channel evidence only for the support type and conditions it covers. For MX channel, "EAD-tested" applies within the tested scope. A general statement about channel is not enough to show that a bracket, bearer and rod combination matches that scope.
Custom steel can be considered when the required support type, span or service arrangement sits outside the appropriate channel route. The section, frame, connections and vertical supports can be designed for the actual arrangement and then assessed together.
For custom steel, fire resistance is assessed using EN 1993-1-2. Serviceability is checked using EN 1990 and EN 1991 load combinations. Those calculations apply to the designed support and its recorded assumptions. They are not a general result for every fabricated frame.
The drawing needs to show what the calculation covers. Identify the steel section, the position of the services, the bearer or frame geometry, each connection and the fixing to the building. If channel is attached to the steel frame, show where and how it connects. If vertical supports use steel sections or threaded rod, identify those too.
A hybrid steel-and-channel support may suit a design where a steel frame carries channel bearers. The route should be clear in the drawing and the report. EAD-tested channel data cannot be carried across as a blanket claim for the custom steel frame.
Review the drawing and report as a pair. Match the section, connections and building fixing shown on the drawing to the calculation notes. Check that the service arrangement, fire condition, assumptions and any deflection requirement are stated. If the report describes a different support or does not show how the frame attaches, return the query to the designer. A calculation summary without its drawing leaves the installer to guess which configuration was assessed.
When comparing quotations, compare the support configuration and engineering route, not only the section description. Two supports can use similar steel sizes but different connections or geometry. Ask for the drawing and report for the offered support before accepting a substitution.
Before the support is procured, ask for the design basis and the physical arrangement covered by the evidence. Check that the drawing identifies the service arrangement, the sections, geometry, connections and building attachment. The technical report should explain the calculation basis, fire condition and assumptions.
On site, compare the installed detail with that drawing. Check the position of rods, brackets and connections before services are loaded onto the support. A site change made to clear a duct or another service can affect the support geometry. If the change is necessary, refer it to the responsible designer and keep the revised design information with the installation.
The report is useful at review and handover when it makes the design traceable. A reviewer should be able to see what was assessed, what components were included and which assumptions apply. That lets the project team compare the evidence with the support they can actually see.
Before procurement, make sure the calculation or evidence route is visible on the support drawing. Ask which section and connection details are included, which fire condition applies and what assumptions have been made at the building attachment. If the design uses channel, confirm that the MX components and support type sit within the tested scope. If it uses custom steel, check that the report identifies the designed steel members and connections.
The site team can then use the issued drawing as a check during installation. Confirm that rods, brackets and connections are in the stated positions before services are placed on the frame. If a service clashes with the support, ask for a revised detail rather than cutting, moving or substituting a part without review. Record the final configuration with the report so the design can be checked at handover.
With FRS, you receive physical supports and a fire engineering report. MIDFIX carries design responsibility, backed by professional indemnity insurance. The report and supplied supports relate to the stated design. The installation needs to follow the issued drawing, and any change should be reviewed against that design.
For broader standards context, read fire standards for M&E supports. For the difference between fire test evidence and a general product claim, see fire tested vs fire rated. The FRS page explains the support design service. For life-safety cable systems, see BS 8519 and cable supports.
Steel strength and rigidity fall as it heats. Strength diminishes significantly at around 500°C and falls to 4% of its original strength after 90 minutes. These figures are not ratings for an individual support.
For channel-based supports, EN 1993-1-2 is considered valid up to around 600°C. Above that boundary, calculations alone are unreliable. Use the MX channel evidence only within its tested scope.
Consider it when the support type, span or service arrangement sits outside the appropriate channel route. The custom steel design is assessed for its stated fire condition and geometry.
No. "EAD-tested" applies only to MIDFIX MX channel within its tested scope. Custom steel follows a separate design route using EN 1993-1-2 for fire resistance.
You receive physical supports designed for the stated fire requirement and a fire engineering report. MIDFIX carries design responsibility, backed by professional indemnity insurance.