How to not exceed Power requirements

[Droogie 2001]

As I have recently moved to a CCD I have started to rely on using mains power to run both the camera and my laptop. This means I run an open cable reel from my weather resistant power socket, the reeled cable has x4 sockets and is rated at 13A.

I then attach a surged protection extension cable block to the reel cable. This is rated at 10A and is housed within a weather proof box.

My question is that I now want to add mains power to my mount which requires 12V at 5A.
The reasoning behind this is to primarily address a possible lack of voltage from my 4-year-old Power Tank which maybe causing mount accuracy issues. (another story)

From my very basic understanding this will mean I am over the safe limit for Amps?

That’s is:

Laptop 5A, CCD 5A, mount 5A which equals 15A.
Reel Cable= 13A
Extension Block = 10A

So whatever I plug into means I will be exceeding the safe limit? Is this correct?

The only obvious solution is to purchase another reel cable and run that from a second mains power socket I have.
Despite looking for a 17A reel they do not appear to be any available, I assume because this is regarded as too dangerous?

I ask the question because I would imagine that a lot of people have similar setups so I am interested in seeing how other people address this.

I don’t mind buying another reel it’s just more cabling and setup time but I would rather this than damaging my kit.

Thanks

[Dr_Ju_ju]

your equating DC voltage\current ratings and converting that into AC rating, which isn't the case....  so a 13amp mains power supply rates at 230 volts gives you 2990 watts, so use this as a starting figure, and then calculate for each devices' POWER requirement use the formula of voltage times current to give individual wattages, which can then be subtracted from 2990 watts....

[MarkyD]

Ohms Law

P = VI

I = P/V

You will be using Maximum (assuming all the appliances are 12V)

12V x 15A = 180Watts

For the AC input this equates to

180W / 230V = 800mAmps (0.8Amps)

On another note:

If your sockets are not RCD protected at the Consumer Unit please purchase an RCD extention/adaptor to plug into the outside socket

[Droogie 2001]

Thanks Okay so I have looked them up:

The mount is 12v  is 60W (at least this is what the Baader Outdoor supply is at)

The CCD is 12v 60W

The laptop is  20V 65W

All are 5 Amps

Does this mean I am well within safe limits?

I am still confused by the Amps rating?

 

[MarkyD]

Yes as you will be only drawing 0.8Amps on the 230V AC side

[Droogie 2001]

Okay so just because it is noted as having a 5 Amp rating it really depends on the voltage and watts as to what the real Amps draw is?

I know I should have paid more attention to Physics lessons.

It makes sense as I did think that none of my kit looks like it is that power hungry that it needs two power reels!

[MarkyD]

Yes

A 5A load at 12V = 60W which equates to 0.26Amps at 230V

A 5A load at 24V = 120W which equates to 0.52Amps at 230V

and so on

Watts is the common denominator

[Droogie 2001]

15 minutes ago, MarkyD said:

On another note:

If your sockets are not RCD protected at the Consumer Unit please purchase an RCD extention/adaptor to plug into the outside socket

I have an RCD built into the 10A 4 way adapter that the devices will plug into. The RCD adapter then plugs into the Power reel. Is that okay for protection?

 

[MarkyD]

Yes

Check your Consumer Unit as you may have one on the Socket Circuits (Ring or Radial).  It will have marking stating the trip current - 30mA if you have one.  If you have one installed you don't need the others.  It would be a good idea to test it aswell

[iapa]

1 hour ago, Droogie 2001 said:

As I have recently moved to a CCD I have started to rely on using mains power to run both the camera and my laptop. This means I run an open cable reel from my weather resistant power socket, the reeled cable has x4 sockets and is rated at 13A.

I then attach a surged protection extension cable block to the reel cable. This is rated at 10A and is housed within a weather proof box.

My question is that I now want to add mains power to my mount which requires 12V at 5A.
The reasoning behind this is to primarily address a possible lack of voltage from my 4-year-old Power Tank which maybe causing mount accuracy issues. (another story)

From my very basic understanding this will mean I am over the safe limit for Amps?

That’s is:

Laptop 5A, CCD 5A, mount 5A which equals 15A.
Reel Cable= 13A
Extension Block = 10A

So whatever I plug into means I will be exceeding the safe limit? Is this correct?

The only obvious solution is to purchase another reel cable and run that from a second mains power socket I have.
Despite looking for a 17A reel they do not appear to be any available, I assume because this is regarded as too dangerous?

I ask the question because I would imagine that a lot of people have similar setups so I am interested in seeing how other people address this.

I don’t mind buying another reel it’s just more cabling and setup time but I would rather this than damaging my kit.

Thanks

HTH

You are probably better working with the over all power requirement for each PSU.

Multiply the output voltage for each PSU that you are using to get the power output (Watts = Voltage x Current)

e.g. my CCD PSU is 12V 2A, so provides 12W.

Add the power rating for each power supply together, that will give you an indication of the power you need to have.

Your 13A wall socket (assuming UK) will nominally provide 240A x 13A = 3120W*.

Because you have added the surge protection block, this limits your maximum available power to 2400W* (you quoted a 10A maximum current rating). So, 2400W is the number you cannot exceed. That is a lot of 12V power supplies (20 actually).

This should be more that you will actually need for a laptop, mount power, ccd, focus motors etc.

I've often actually run a desktop, monitor, laptop, two mounts, a DSLR on each (I use mains power on them to make sure I don't suffer flat battery syndrome), a couple of CCD cameras and two heater strips all from one extension power cable. Having said that, I'm planning on putting heater strips on a different extension reel back to a different wall socket.

You will not find any extensions cable that plugs into the wall socket in the UK, that has a current rating greater then 13A.

*not strictly true because your mains supply current alternates and is not always in phase with the voltage your total power in Watts will be a little bit lower. So at any particular point in time the instantaneous power varies from 0 to whatever the product of voltage x current is. We don't need to worry about that too much  

Oh, I suppose I should point out that your mains adapters are not 100% efficient, so they use a little more power than they provide at the output. Again, we don't worry about that.

[MarkyD]

5 minutes ago, iapa said:

HTH

You are probably better working with the over all power requirement for each PSU.

Multiply the output voltage for each PSU that you are using to get the power output (Watts = Voltage x Current)

e.g. my CCD PSU is 12V 2A, so provides 12W.

Wrong  = 24Watts

Your 13A wall socket (assuming UK) will nominally provide 240A x 13A = 3120W*.

Wrong.  UK supply is 230Volts = 2990 Watts at 13Amp  (Not 240Amps as you have stated)

 

 

[Droogie 2001]

Thanks Iapa and all of the others who have given me a lesson on power usage. That's a lot of kit your running.
I have added up all of my devices and I appear to be drawing 1.2Amps. So my 10A Surge Protected 4 way adapter should have no issues there.

I believe being outside in the cold can also affect the power consumption.

Anyway just want to protect my investment. For the sake of a bit of checking and planning could be the difference between having a disaster and being covered for any unforeseen power issues.

 

 

[iapa]

On 22 June 2016 at 12:50, MarkyD said:

 

Point 1 - taken, I can't count

OK I said 240A X 13A. Obviously a typo.

Re 240,V. a moot point as today's h 230V 'standard' is a definition.  

As I recall, the EU decided that the UK conformed to their 230V 'standard'' so the UK changed legislation to define as 230V +10%/6% about 15 years ago, or thereabouts.

It is still nominally 240V when measured.