Whether or not you can feel 24 volts of electricity is dependent on a few key factors. Voltage by itself does not determine whether a shock will be painful or dangerous. Other important factors include the amperage (current) of the electricity and the resistance of your body. Generally, higher voltages allow more current to flow through your body, making shocks more likely to be felt and potentially harmful. However, even relatively low voltages like 24V can be felt or cause harm under certain conditions.
Key Factors That Determine If You Can Feel 24 Volts
Voltage
Voltage is a measure of the electric potential difference between two points in a circuit. It is measured in volts. Higher voltage allows more current to flow through a resistance. 24V is considered low voltage compared to the 120V in household outlets or the several thousand volts in high power lines. However, even 24V is well above the threshold needed to carry dangerous amounts of current through the body under some conditions.
Current (Amperage)
Current is the flow of electric charge measured in amps. While voltage represents potential, current is what actually delivers energy through your body. Even a high voltage by itself cannot shock you unless current is flowing. The amount of current that will flow through your body for a given voltage depends on resistance. Amperage of even a fraction of 1 mA (milliamp) can be felt. 10-200 mA can cause painful shocks and muscle contractions. Above 200mA, the current can more easily disrupt heart rhythms and respiration, potentially leading to death.
Resistance
The resistance of the path the current takes through your body heavily influences whether you will feel a shock. Dry intact skin has very high resistance, around 100,000 ohms. If your skin is wet or the current passes through an open wound, resistance may drop below 1,000 ohms. Internal body tissues and the bloodstream provide around 300 ohms of resistance if current passes through them. Given 24V and 300 ohms of resistance, Ohm’s law predicts a current of 0.08 Amps (80 milliamps), well above the threshold of sensation and capable of causing pain and muscle contractions.
Duration of Contact
The longer the current path remains intact allowing current to flow through your body, the greater the magnitude and duration of physiologic effects. Very brief accidental contacts may startle you without causing pain or injury. Sustained contact increases risk significantly.
Can You Feel 24 Volts?
Based on the factors discussed above, 24V certainly can be felt and can cause pain and injury if conditions allow sufficient current to flow through your body. However, it is not guaranteed that contact with 24V live wires will result in sensation or harm. Brief, accidental brush contact with 24V may do nothing more than startle you. On the other hand, sustained contact or contact with broken skin can result in painful shocks, burns, and muscle contractions.
Here is a table summarizing the effects of current through the body:
| Current Level | Typical Effect |
|---|---|
| Less than 1 mA | Typically not felt |
| 1-10 mA | Painful shock felt; “let-go” range where muscles contract |
| 10-200 mA | Painful shocks; loss of muscle control |
| 200-500 mA | Potentially lethal; respiratory arrest, heart rhythm disruption |
As this table demonstrates, even currents of just 1-10mA, which 24V can easily deliver under the right conditions, can cause painful and involuntarily muscle contractions. While not guaranteed to happen, it is definitely possible to feel 24V.
When Is 24 Volts More Likely To Be Felt?
The following conditions increase the likelihood that 24V will deliver a painful or hazardous shock:
Wet Skin or Environment
If your skin is wet or sweaty, resistance is lowered significantly, allowing more current to flow from any given voltage. Even standing in a damp environment can increase risk from 24V exposure.
Broken Skin
Any break in your skin bypasses the protective resistance of intact dry skin. Cuts, scrapes, or puncture wounds dramatically reduce resistance and allow much higher current flow from 24V.
Contact with Both Wires of a Circuit
Touching just one 24V wire may result in only a tingle. However, if you touch both the positive and negative wires and complete a circuit through your body, you will receive the full brunt of the 24V difference.
Sustained Contact
The longer you remain in contact with a live voltage source, the greater the effects on your body. Brief brushes may have no effect, while holding the wires allows time for current to start disrupting your heart or breathing. Letting go quickly reduces overall exposure.
Paths Through Sensitive Internal Tissues
If current passes through your chest and circulatory system, 24V applied externally can potentially be much more dangerous than the same voltage applied to limbs.
Use of Medical Devices
Implanted devices like pacemakers reduce the body’s inherent electrical resistance. Currents as low as 15mA can interfere with these devices, so 24V may disrupt them where it would not affect others.
Precautions When Working With 24V Systems
Though not as hazardous as household 120V, 24V wiring and devices should still be handled carefully:
Avoid Contact with Bare Wires
Do not touch uninsulated wiring or terminals. Ensure wires are fully insulated or enclosed. Double up on insulating tape.
Keep Work Area and Self Dry
Eliminate damp conditions that reduce skin resistance when working on 24V circuits. Stay dry.
Wear Insulating Gloves and Footwear
Use rubber insulated gloves rated for electrical work. Wear rubber-soled shoes.
Cover Any Broken Skin
Use proper bandages or dressings to cover any cuts, scrapes or wounds if working with 24V.
Limit Sustained Contact Time
Use only one hand when possible. Avoid grasping wires for extended periods even when off. Let go quickly after accidental contact.
Be Careful Around Sensitive Areas
Avoid contact across the chest as current can more easily disrupt heart rhythm.
Those With Medical Devices Use Extra Caution
Follow device guidelines regarding voltage exposure due to lower resistance.
What’s So Dangerous About Current Through The Body?
Current passing through tissues can disrupt normal electrical signaling required for vital body functions:
Heart Rhythm
As little as 30mA across the heart can cause fibrillation, an uncontrolled quivering that is often lethal. Even currents too low to cause fibrillation can still disrupt rhythm.
Breathing
Current paths through the chest and diaphragm can paralyze muscles required for breathing. Loss of breathing leads to death rapidly if not corrected.
Nerve and Muscle Function
Currents above the let-go threshold of 10mA across a limb can make muscles violently contract out of your control. Very high currents damage nerves and muscles directly through heating effects.
Burns
Current focused on small areas of skin causes severe localized burns. These can be internal or external depending on the contact points.
Conclusion
While 24V systems are considered low voltage, under the right conditions they can indeed deliver a painful or even hazardous shock due to the resulting current flow through your body. Factors like skin moisture and resistance, contact with live and ground wires, and sustained contact time all play a role in determining if 24V will be felt. Precautions like insulation, dry conditions and limiting sustained contact are advised when working with 24 volt systems. Though the shock may not be guaranteed to happen, it is best to treat 24V with healthy respect to avoid potential injury.