Manual transfer switch

A manual source-transfer switch is an electrical switch that transfers an installation's supply between two separate sources through the direct action of an operator. Unlike automatic transfer switches, it operates without a detection relay or monitoring electronics, making it particularly suited to occasional or backup switching. The Socomec COMO, SIRCO and SIRCOVER ranges cover ratings extending up to several thousand amps and comply with IEC 60947-6-1.

Operating principle and differences from the automatic transfer switch

Direct manual control by handle

The manual source-transfer switch is characterised by direct mechanical control via a rotary or linear handle. The operator carries out the switch between the main source and the backup source personally, without a voltage relay or a PLC being involved. Our installation experience confirms that this mechanical simplicity significantly reduces the risk of electronics-related failure in disturbed environments.

Operational distinction from automatic solutions

Unlike an automatic source-transfer switch, which detects a network outage and switches within seconds, the manual transfer switch requires human intervention. This fundamental difference makes it suited to installations where switching is not constrained by a critical response time, or where the backup source is not permanently on standby. In the field, we observe that installations with a non-self-starting generator set are the most common use case.

Ranges and ratings available for Socomec manual source-transfer switches

The three ranges: COMO, SIRCO and SIRCOVER

The COMO range is aimed at modular applications and distribution panels, with compact ratings for visible isolation. SIRCO and SIRCOVER are the industrial ranges, the latter incorporating a visible-break function for maintenance operations. Our commissioning tests show that the choice between these ranges mainly depends on the required breaking capacity and the need for isolation in the open position.

Rated current ranges and mounting

Available ratings extend from modular values up to several thousand amps for flush-mounted or enclosed versions. This modularity allows both tertiary panels and industrial distribution boards to be equipped. Our installation feedback shows that versions up to 2500 A represent the core of the market for network/generator-set switching.

Compliance standards and mechanical construction

IEC 60947-6-1 certification for transfer switches

The IEC 60947-6-1 standard defines the specific rules for transfer switches, including short-circuit withstand requirements, utilisation categories and electrical ageing tests. Compliance with this standard guarantees that the manual source-transfer switch retains its breaking capacity after a defined number of on-load operations.

Materials and mechanical reliability over time

The reinforced polyamide body provides dielectric rigidity and resistance to thermal shock in the electrical panel. Silver-plated copper contacts limit oxidation and preserve conductivity after years of intermittent service. Feedback from installers confirms that this robust construction is a major asset in dusty or damp industrial environments.

Typical applications and installation choices

Manual switching between the network and a generator set

The most common application concerns installations with a backup generator set without automatic start-up. The operator manually starts the generator, checks its stability, then operates the manual source-transfer switch to supply the installation. Our standard practice favours this sequence in agricultural buildings, small industries and moderately critical municipal infrastructure.

Moderately critical installations and occasional use

Sites where continuity of service is not vital, or where an operator is constantly present, find in the manual transfer switch a relevant economic trade-off. It avoids over-specifying control electronics for weekly or monthly switching. We also recommend this solution for periodic generator-set testing, where switching controlled by a technician offers a safety advantage.

Frequently asked questions

What is the difference between a manual source-transfer switch and a disconnector?

A manual source-transfer switch has at least three terminals (two inputs, one common output) and can switch the load from one source to the other. A disconnector only provides circuit isolation with no transfer function, with two terminals per pole.

Can a manual source-transfer switch replace an ATS in a critical installation?

No, because an ATS (Automatic Transfer Switch) switches within seconds without human intervention. The manual transfer switch introduces an unpredictable delay linked to the operator's presence and responsiveness, which is incompatible with sensitive loads or uninterrupted industrial processes.

Does the IEC 60947-6-1 standard also apply to automatic transfer switches?

Yes, the IEC 60947-6-1 standard covers all transfer switches, whether manual, motor-operated or automatic. It defines specific utilisation categories according to the transfer's triggering mode.

What maintenance is recommended for a manual source-transfer switch?

Maintenance is generally limited to a visual check of the contacts, terminal tightening and mechanical lubrication in line with the manufacturer's recommendations. Frequency depends on the number of annual operations; for occasional backup use, an annual check is often sufficient.

Are the SIRCO and SIRCOVER ranges interchangeable on the same chassis?

No, although similar, these ranges have internal construction differences linked to the visible-break function. Replacing one model with the other requires checking the compatibility of the fixings and connections with the existing support.