[tonyc56]

Hey Guys,

Please bear with me i'm ignorant when it comes to electrical systems. I've always wondered why do they make low voltage systems. Why not make all systems lets say 120 volts except obviously when higher voltage is required. What is the advantage of having a low voltage motor, thermostat, etc...

 

[Inner10]

Hey Guys,

Please bear with me i'm ignorant when it comes to electrical systems. I've always wondered why do they make low voltage systems. Why not make all systems lets say 120 volts except obviously when higher voltage is required. What is the advantage of having a low voltage motor, thermostat, etc...

Although 120 isn't really high... low voltages are safer and cheaper because they require less insulation and less space between conductors. Also in controls DC is often used.

 

[tedanderson]

I've always wondered why do they make low voltage systems.

I would have to say that it's for the same reason that the tub, toilet, shower, and vanity sink ended up in the same room together.

When low voltage systems were first being engineered, I'm sure that the people developing them never knew that they would be under an umbrella with similar technologies. They just knew that they were inventing something to fulfill a need. Then eventually many of these technologies ended up in homes.. and then someone figured that it made sense to group them together.

Like with the phone- 50 years ago nobody thought of it as being a "low voltage" device. Even the manufacturers of PBX systems were probably working towards an efficient design more so than the thought of specifically using "low voltage" to build their equipment. Then came cable TV and internet... then high speed internet.. so home builders figured that houses should have a "commercial" type of voice and data infrastructure.

Then from that point it began to snowball.

 

[rrk]

I would say safety was the main reason it started. First with single family home doorbell & thermostat systems. Then it progressed to multifamily door buzzer and fire alarm systems, and institutional master clock and fire alarm systems. The wire costs were the same since they used the same exact wire at the time, but the buzzer coils, clock impulse coils, and clock switch gear were all exposed. Most institutional systems were DC from the beginning in the 20s.

Early fire alarm systems were very crude micro switches with toothed gears activating the switches. Master clocks used brass springs to make contact through holes in a paper taper to make classroom bell ring.

For a short time pneumatics were thought to be the successor to low voltage, but they had many problems with those once set up in the field.

 

[smarthouse]

Agreed. Wiring that isn't low voltage have a much higher chance of having issues, generating heat, etc. when inside the wall. Speaker wire is low voltage and I usually use shielding, but mainly to protect from interference from power lines than to protect the system from overheating and having fire issues. Also, certainly you can cut speaker wire or coax cable etc. without worrying about shocking yourself. I had a client recently (www.facebook.com/smarthousesolutionsms) who was using telephone wires to run speakers. It can work, but not very well.

 

[Inner10]

Agreed. Wiring that isn't low voltage have a much higher chance of having issues, generating heat, etc. when inside the wall. Speaker wire is low voltage and I usually use shielding, but mainly to protect from interference from power lines than to protect the system from overheating and having fire issues. Also, certainly you can cut speaker wire or coax cable etc. without worrying about shocking yourself. I had a client recently (www.facebook.com/smarthousesolutionsms) who was using telephone wires to run speakers. It can work, but not very well.

Don't it increases the capacitance, not good for speaker wire.

 

[smarthouse]

Yeah agreed... I got the call because the in-ceiling speakers weren't working. Ripped out the telephone wires and replaced with 14 gauge speaker wire and problem solved.

 

[SectorSecurity]

Yeah agreed... I got the call because the in-ceiling speakers weren't working. Ripped out the telephone wires and replaced with 14 gauge speaker wire and problem solved.

Im betting they realized a box of quad was half the price of 14ga and figures what's the difference

 

[Inner10]

Im betting they realized a box of quad was half the price of 14ga and figures what's the difference

Fine for 70/100v.

I was referring to sheilded wire.