Choosing correct amp for camera power supply.

[manishpmch 0]

I have a 8 channel dvr. Have connected only 6 cameras (each 48 IR requiring 12v 1000mA). 5 of them are max 30 feet(~10 Mtrs) away from DVR but the 6th is about 50 Mtrs away. I tried a 5 Amp power supply. Everything worked fine except Night Vision on the 6th camera. What type of power supply should I use? How many Amps? I also plan on attaching 2 more similar cameras to the power supply in the future. Would I have to change the power supply after adding these cameras. (I prefer single power supply for my cameras).

 

Also would a high Amp power supply (much more than needed) damage my cameras?

Thanks in advance

MK

[Owain 0]

6 x 1A (1000mA) is 6A. A 5A supply will not be sufficient.

 

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

 

Each camera should be wired separately to the power supply with its own fuse or circuit breaker.

[manishpmch 0]

6 x 1A (1000mA) is 6A. A 5A supply will not be sufficient.

 

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

 

Each camera should be wired separately to the power supply with its own fuse or circuit breaker.

 

 

Thank you very much for your reply... But what about loss due to long cables?

[Owain 0]

6 x 1A (1000mA) is 6A. A 5A supply will not be sufficient.

 

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

 

Each camera should be wired separately to the power supply with its own fuse or circuit breaker.

 

 

Thank you very much for your reply... But what about loss due to long cables?

 

50 metres is quite long even with decent cable. If you are using AWG cable there's a calculator at

http://www.calculator.net/voltage-drop-calculator.html

For metric cable use

http://www.bbowner.co.uk/volt-drop-cable-size-calculator.html

or measure the voltage at the camera.

 

If the volt drop is too high then you'll need to

(a) use a thicker cable

(b) parallel up cables

© use local power to the camera

(d) use 24V and a 24V compatible camera

Edited January 26, 2013 by Guest

[Owain 0]

For a 3% volt drop using twin cable, 50 metres, 12V 12 watts 1 amp, you are looking at 6mm cable. That's what we use in the UK for wiring cookers.

[tomcctv 187]

For a 3% volt drop using twin cable, 50 metres, 12V 12 watts 1 amp, you are looking at 6mm cable. That's what we use in the UK for wiring cookers.

 

 

this is a joke yes ?????

 

 

I have a 8 channel dvr. Have connected only 6 cameras (each 48 IR requiring 12v 1000mA). 5 of them are max 30 feet(~10 Mtrs) away from DVR but the 6th is about 50 Mtrs away. I tried a 5 Amp power supply. Everything worked fine except Night Vision on the 6th camera

 

 

power supply is too small 6x 1amp on 5amp power supply.

 

also you will get problems with surge when cameras go into IR.

 

best running two cameras on 1 5amp power supply ... so you need 3 power units or go with a good power distribution box. look for 10amp in total

[GrouchoBoucho 0]

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

regulated has nothing to do with it - that only limits the voltage. a 50a power supply would be just as safe, regulated or not, as a device will draw only as much current as it needs.

[Owain 0]

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

regulated has nothing to do with it - that only limits the voltage. a 50a power supply would be just as safe, regulated or not, as a device will draw only as much current as it needs.

 

But with an unregulated supply the voltage can rise at low loads, which could damage the device.

[GrouchoBoucho 0]

A higher than needed amp rating will not damage cameras, provided it is regulated, which any proper CCTV supply will be. (Cheap wall-warts often aren't.)

regulated has nothing to do with it - that only limits the voltage. a 50a power supply would be just as safe, regulated or not, as a device will draw only as much current as it needs.

 

But with an unregulated supply the voltage can rise at low loads, which could damage the device.

true, but that has nothing to do with the power supply's current capabilities.

 

and frankly, there are very, very few cheap cameras out there that won't nicely handle an unregulated supply. it's only the last 2-3 years that switching power supplies have become really common; before that, the vast majority of individual 12v supplies were unregulated. it was only the crappiest cameras that ever had an issue with this.

[Owain 0]

For a 3% volt drop using twin cable, 50 metres, 12V 12 watts 1 amp, you are looking at 6mm cable. That's what we use in the UK for wiring cookers.

this is a joke yes ?????

 

No.

 

The calculation is as shown here, from the bbowner website above.

 

6mm cable has a rating of 47A (clipped direct to wall) or 31A (enclosed in conduit in thermally insulating wall). UK cooker circuits are usually 30A fuse or 32A circuit breaker. Diversity on a domestic cooker is calculated at the first 10A + 0.33 of the remaining. Diversity can be applied to a cooker, since this appliance contains a number of loads, rings, grill, oven, and it is reasonable to assume that not all parts of the cooker will be used at full power at the same time.