Shielded power cables have several negative points and potential downsides compared to unshielded ones, largely stemming from increased complexity and physical characteristics.
Key Negative Points of Shielded Power Cables:
Proper Grounding Requirements:
For a shield to work, it must be properly grounded. Improper grounding (e.g., leaving the shield floating or grounding both ends incorrectly) can lead to ground loop interference.
Lower Current Capacity:
In some cases, the shield can reduce the overall maximum current rating of the cable due to induced heat.
Limited Low-Frequency Effectiveness:
At low frequencies (like 50/60 Hz mains electricity), magnetic fields can penetrate most common shields.
Diminishing Returns:
For many standard applications, shielding the last few feet of a power cord is considered unnecessary because the electrical interference is not shielded in the walls back to the power company.
When Shielding Causes Issues:
If the shield is not connected at both ends, it may fail to protect against magnetic fields, and if it is connected at both ends, it can create a ground loop, which may introduce hum and noise, particularly in audio systems.
Key Negative Points of Shielded Power Cables:
Proper Grounding Requirements:
For a shield to work, it must be properly grounded. Improper grounding (e.g., leaving the shield floating or grounding both ends incorrectly) can lead to ground loop interference.
Lower Current Capacity:
In some cases, the shield can reduce the overall maximum current rating of the cable due to induced heat.
Limited Low-Frequency Effectiveness:
At low frequencies (like 50/60 Hz mains electricity), magnetic fields can penetrate most common shields.
Diminishing Returns:
For many standard applications, shielding the last few feet of a power cord is considered unnecessary because the electrical interference is not shielded in the walls back to the power company.
When Shielding Causes Issues:
If the shield is not connected at both ends, it may fail to protect against magnetic fields, and if it is connected at both ends, it can create a ground loop, which may introduce hum and noise, particularly in audio systems.
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