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Within the realm of kitchen ventilation systems, a persistent challenge has emerged over time: the recurrent failure of these gas interlock systems. Often, this issue is attributed to the limited expertise and understanding of electrical systems possessed by the contractors and installers responsible for their installation.

Supply Chain Dynamics

The systems are commonly provided by ventilation suppliers utilizing their own supply chains, rather than the contractor employing self-sourced, dependable equipment.

Key Challenges

The challenges we’ve encountered stem from instances where we’ve been called in for assistance or to provide technical advice to electrical contractors responsible for projects where we’ve subsequently installed kitchen ventilation systems.


Non-functional Extract/Supply Fan. One commonly reported issue is associated not with the fan itself, but rather with the gas interlock system. This arises when an air pressure differential switch is utilized within the ductwork. Installers who lack the expertise to configure these switches correctly tend to misdiagnose the problem due to factors such as improper tube placement, incorrect positioning of P1/P2 spigots, or the use of speed controllers with a variable current monitored gas interlock panel.

Overcomplexity Concerns

The prevalent installation of gas interlock panels with integrated current monitoring has led to unintended complications. This typically involves splitting the electrical supply to the fan. However, this can give rise to various problems.

Challenges from Splitting Supply Cables

  • Excessive heat buildup on the terminal block can cause separation from the main PCB. While this might not prove disastrous for single-phase fans, it can be detrimental to three-phase setups by causing motor overheating.
  • Such installation practices often neglect best practices. The need to split the neutral connection usually results in loose terminal blocks, a situation not often accommodated by manufacturers. Additionally, controls are often kept separate, with few installers opting for trunking. This results in multiple split connections within the spurs or gas interlock panel.
  • Separating line conductors when using an inverter for a three-phase fan can trigger faults in the inverter.
  • Failure to account for the higher single-phase current when using a single to three-phase inverter, and routing the supply through the gas interlock panel first, can lead to overcurrent issues on the gas interlock PCB.

Motor Protection Factors

Issues arise when installers either disregard motor protection or set incorrect current ratings on overload relays. This can compromise the gas interlock system’s reliability. In some cases, the absence of an overload relay on the three-phase fan supply can prevent supply interruption, thereby failing to protect the motor.

Simplified Solution

Simplicity proves to be the solution. We advocate for independent motor protection and separate wiring for the gas interlock and fan. This approach offers several advantages:

  • Easier fault identification: It either works or it doesn’t.
  • Elimination of electrical supply splitting for fans.
  • Neat and secure electrical installations.

Implementation Approach

Our approach involves the use of straightforward, cost-effective, and dependable gas interlock panels devoid of built-in current monitoring. We ensure motor protection through methods like DOL starters, inverters, or single-phase speed controllers with overload protection. We employ remote current switches that can be neatly integrated into DOL starters, inverters, isolators, or fan terminal boxes.

Proven Reliability

Our installation methodology has undergone rigorous testing and has proven to be exceptionally reliable, resulting in minimal callbacks. The approach is user-friendly, often allowing for issue resolution via phone or video calls, thus reducing the need for on-site visits.

Anticipating “What If”

  • Turning off the isolator to the fan interrupts current flow through the current switch, thereby deactivating the gas supply.
  • The likelihood of extract ductwork disconnection is low, given the absence of flexible connections. The scenario would mirror a gas interlock system with built-in current monitoring.
  • In the case of belt-driven fans, remote current switches are not recommended due to potential motor continuation despite belt detachment. An air pressure differential switch would be more suitable.
  • Working with three phase fans – The remote current switch encircles one power phase. In the event of an issue with that phase, devices like the overload relay or inverter detect the anomaly. Consequently, they halt power to the fan motor, a protective measure against imbalances among the three power phases.

Integration with Other Systems

Further integration, including call points and fire alarm systems are standard. The primary focus of this post is elucidating the synergy between the gas interlock panel and fan control.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_cta h2=”Food for thought?” h4=”Contact us to discuss a new gas interlock system or upgrade your current system” style=”3d” add_button=”bottom” btn_title=”Contact Us” btn_color=”success” btn_size=”lg” btn_i_icon_fontawesome=”fas fa-at” btn_css_animation=”bounceInUp” btn_add_icon=”true” btn_link=”url:http%3A%2F%2Fimperialgreensystems.com%2Fcontact|title:Contact”][/vc_cta][/vc_column][/vc_row]

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