TE Connectivity Relay Selection: C300 vs G100 and the 'vs Cisco' Confusion

Let me save you some scrolling: if you are searching for the best TE Connectivity relay, there isn't one. There is only the relay that fits your system. I say this as a quality inspector who reviews component deliveries before they go to production—roughly 1,600 line items a year. And I have rejected about 6% of first deliveries in 2024 for spec mismatches that the engineering team had missed.

When I first started working with high-voltage DC contactors, I assumed the higher current rating was always the safer choice. A C300 can switch more current than a G100, so it must be better, right? Three prototype failures later, I learned that better depends on coil draw, package space, heat rejection, and the exact duty cycle of the load.

There Is No Universal Answer—Here Is My Decision Frame

In my experience, the TE Connectivity relay decision usually falls into one of three scenarios. Look at the list, find your situation, and the rest of this article will give you a more specific recommendation. If you are comparing TE Connectivity vs Cisco, that is a fourth scenario—but it is a category comparison, not a relay selection.

• High-current main switching (over 100A continuous, EV/ESS) → C300 family
• Auxiliary, pre-charge, lower-current loads (100A or below) → G100 family
• Compliance- and qualification-driven programs → start with the standard, not the part number
• TE Connectivity vs Cisco → you are solving a network or system architecture problem, not a component problem

Scenario 1: Main Battery Disconnect—C300 Territory

If you are working on an electric vehicle, energy storage rack, or industrial vehicle and need a main relay for a DC bus that draws more than 100A continuous, the C300 family is where I start. The C300 is a 300A-class KILOVAC contactor, designed for high-voltage DC switching. That design target shows up in the contact gap, the arc suppression, and the thermal behavior.

The word 'contactor' matters. TE Connectivity uses the KILOVAC line for applications where a relay has to interrupt real power, not just signal a controller. According to TE Connectivity's relay overview (te.com, accessed January 2025), KILOVAC contactors are positioned for high-voltage DC switching.

My honest limitation here: if your load is above 300A continuous, or if you need a sealed/helium-filled package for a submersion requirement, the C300 is not the right family. That is not a weakness. It is a boundary. Trying to stretch a part past its design envelope is how expensive smoke tests happen.

In Q1 2024, we audited a battery pack design where the engineer wanted a C300 for a 65A load because the 'extra margin felt safer.' The team changed to a G100 after a coil-power review and reduced the control board cost by about 18%. The relay was not the bottleneck; the coil drive circuit was.

Scenario 2: Pre-Charge and Auxiliary Loads—G100 Territory

For pre-charge circuits, BMS power, heater loads, or any auxiliary switching where the current stays under 100A, the G100 often makes more sense. It has a smaller package and lower coil power, which matters when your control board is already packed. The G100 is not a cheaper C300. Let me rephrase that: it is a different contact design, not just a derated version of the same part.

I went back and forth between the C300 and G100 on a pre-charge prototype for two weeks. The C300 offered more current margin, and the G100 offered a smaller footprint and easier coil drive. Ultimately, I chose the G100 because the load was 60A peak and the board area constraint was real. I also added a flyback diode to the coil circuit. Oh, and I should add that the diode was what the first board was missing—the relay was fine, but the coil driver was not.

In Q4 2024, we quoted both families for a 500-unit program. The G100 unit price came in about 35% lower than the C300. That is one data point, not a universal price claim. Verify with your distributor.

Scenario 3: You Do Not Have a Load Profile Yet

If you cannot answer the question 'what is the continuous current at maximum ambient temperature?' stop at the part number. This is the scenario where the phrase 'we can just use the bigger one' becomes expensive.

When I implement our verification protocol for an $18,000 project, the first thing I request is a load profile. I have rejected first-article relays that passed the current check but failed the derating curve. The datasheet says the C300 can carry a certain current, but that number changes when the ambient temperature inside the enclosure is 70 °C.

The 'buy the biggest relay that fits' habit comes from an era when panel space was cheap and relays were simple. That has changed. The real costs now are coil power, thermal rise, certification, and the board space around the part.

A Quick Note on TE Connectivity Inc.

You might see TE Connectivity Inc. on an invoice, a quality document, or a compliance letter. That is normal. The TE Connectivity Group includes multiple entities; the parent company is TE Connectivity Ltd, incorporated in Switzerland. If the legal entity matters for your approved vendor list, check the quote carefully before assuming a mismatch.

If I remember correctly, the C300 series originally came out of the Kilovac high-voltage product line. I might be misremembering the exact product genealogy, but the high-voltage contactor style tells you that this isn't a miniature PCB relay. It is a part with aerospace heritage.

TE Connectivity vs Cisco: Why the Comparison Is Usually Wrong

Now let's talk about the 'vs Cisco' part of the search. I understand why it shows up. Both companies use the word 'connectivity' in their public descriptions. But a TE relay will not route an IP packet, and a Cisco switch will not switch a 300A DC bus.

Cisco's portfolio is networking hardware, software, and services (according to Cisco's company overview, cisco.com, accessed January 2025). TE Connectivity's portfolio is connectors, sensors, relays, and cable assemblies for electrical and electronic systems. The overlap is the English word 'connectivity', not an actual market category.

Where does a real comparison exist? Only in a system design. For example, if you are building a remotely controlled power distribution unit, you could use TE components for the relay, current sensor, and connectors, and then add a network connection. Or you could buy a smart PDU that already does that. That is a system architecture choice, not a component-level 'TE vs Cisco' choice.

How to Tell Which Scenario You Are In

Here is a quick diagnostic I use with our engineers:

1. Measure/calculate the maximum continuous current at the worst-case ambient temperature.
2. Check how much coil power your control circuit can supply.
3. Check the dimensional and thermal constraints around the relay.
4. Check the applicable safety standards and approved-vendor list.

If the current is above 100A and coil power is not a constraint, the C300 is probably the right family. If the current is below 100A and you are tight on board area or coil power, go with the G100. If you are still within current limits but the enclosure runs hot, choose a contactor with a larger thermal envelope—or add cooling. If you are shopping for network infrastructure, you are in the wrong product category and should be looking at Cisco.

Bottom Line

The C300 and G100 are both good TE Connectivity relays. They are good because they are designed for different jobs, not because one beats the other in a spec sheet fight. The quality issue is not usually the relay; it is the mismatch between the relay and the system around it.

I recommend the C300 for high-current main switching, and I recommend the G100 for lower-current auxiliary switching. But if your load is below 30A, I might recommend neither. That is the honest limitation: sometimes a solid-state relay or a standard PCB relay is the right answer. Knowing when not to use a part is part of quality control. I think that distinction is where most BOM quality problems come from.

And if your search included 'vs Cisco', now you know what it means: component supplier vs network equipment supplier. Don't let the word connectivity fool you.