Disadvantages of Light Bulbs & Lamps Connected in Series?
Series connection for household wiring like fans, switches, light bulbs etc is not a preferred way instead of parallel or series-parallel wiring due to serious disadvantages and flaws as described below.
- If breaks occurs in any part of the circuit, no current will flow and the entire circuit become useless (whole lamps and connected devices will go OFF).
- A high supply voltage is required if the lamps (or other electrical devices) are to be connected in series because voltage across each connected light bulb are additive (shared) in series circuit i.e. VT = V1 + V2 + V3 +…. Vn. If we add more light bulbs in the series circuit, Its mean more resistance because resistance is also additive in the series circuit i.e. RTotal = RT = R1 + R2 + R3 + …Rn. This way, It would not be possible for the light bulbs to get the exact rated voltage. So we will have to increase the supply voltage for efficient system.
- It is not possible to turn OFF or ON a light bulb or any other appliances connected in series circuit. To switch OFF the single light bulb, The whole circuit will be go OFF.
- Two or more light bulbs connected in series would be dimmer than the usual because resistance increases and voltage are shared across the bulbs (low voltages for other bulbs) as compared to single bulb in series as mentioned above. In simple words, current and voltage is reduced due to high resistance and shared voltages in series circuit.
- If the rating of bulbs are different (i.e. Bulb 1 = 60W and Bulb 2 = 100W), the bulb with higher resistance would glow brighter and the other one dimmer. As brightness depends on current and voltage. The bulb which dissipate more power will be brighter i.e. high resistance bulb 1 will dissipate more power and bulb 2 would be dimmer then. (R = V/I = Ohm’s Law).
- Therefor, series wiring connection is not suitable and practicable for lighting circuits.
Good to Know: For efficient operation, only those lamps or devices should be connected in series that have the same current rating. however, electrical devices (e.g., heater, toaster, grinder, lamp etc.) have different current ratings. obviously, they cannot be connected in series for efficient operation.