DIY Extension Cable

[Jay81]

Hi all,

I've been searching around for quite some time for an answer to my question and can't seem to find an answer.

I want to make up an extension lead to carry mains voltage to a 6V transformer plug that is powering a small appliance that can draw up to 200mA when maxed out (although I doubt I will max it out). I need this to go to around 50 metres. Any idea what cable would be good? I'll have other iterations of this but to shorter lengths.

Some suggestions say 2.5mm core for 13A but then I'm drawing far less. Another source said 1.5mm core would be good for 6A and that makes me think this would be ok as it has a 1.5mm sq conductor area: CBBR0068 - PRO POWER - Multiconductor Unshielded Cable, 3, 30 x 0.25mm | CPC UK How low a core size can I go..?

I found some equations but maths really isn't my strongpoint and I can't find my way around them...

Any help would be very much appreciated!

Many thanks, Jay

 

[Pete999]

Hi all,

I've been searching around for quite some time for an answer to my question and can't seem to find an answer.

I want to make up an extension lead to carry mains voltage to a 6V transformer plug that is powering a small appliance that can draw up to 200mA when maxed out (although I doubt I will max it out). I need this to go to around 50 metres. Any idea what cable would be good? I'll have other iterations of this but to shorter lengths.

Some suggestions say 2.5mm core for 13A but then I'm drawing far less. Another source said 1.5mm core would be good for 6A and that makes me think this would be ok as it has a 1.5mm sq conductor area: CBBR0068 - PRO POWER - Multiconductor Unshielded Cable, 3, 30 x 0.25mm | CPC UK How low a core size can I go..?

I found some equations but maths really isn't my strongpoint and I can't find my way around them...

Any help would be very much appreciated!

Many thanks, Jay

Is this for a temporary installation?

 

[Spoon]

How is this 50 meters of cable going from the mains socket to the 6V transformer? E.G. Is it being clipped to a wall for all 50 meters?
Where is the power socket situated?
Where is the 6V transformer situated?
Has the power socked got RCD protection?

 

[amlu]

will be much safer to feed that cable with something like 12 or 24v low voltage, then drop it down to required 6v on the other end.

 

[Richard Burns]

If you are considering a dedicated extension lead for this application then you should be OK with a 1.5mm² cable considering the cable is only going to take 5mA at 230V.
The transformer should be capable of taking a 220V supply.
You may also find it cheaper to buy a 13A rated extension reel of 50m, even if you need different plugs/sockets on the ends the cable cost is lower.

 

[Spoon]

I might be being over cautious Richard but I didn't want to give the OP the info until they answered posts 2 & 3. I can just imagine someone running 50 meters of 1.5mm over a field and public footpath to maybe a boat and when a member of the public questions this they say "Someone on an electrical forum told me it was ok to use this cable"

 

[Jay81]

Thanks for the great response! Apologies for the delayed reply, I'll do my best to keep on top of replying quickly.

In answer to your questions:

This will be for permanent installation and the cable will be tacked to the walls and various beams out of the way of people but in the public domain. It will be dedicated to this use. And good point about going for a reel and changing the connectors Richard.

In terms of taking down the voltage at the mains point, is this for overheating reasons or just in case somebody cuts through the cable?

Many thanks for your help everyone, it is very much appreciated.

 

[Spoon]

Sorry Jay, more questions.
Can you describe more what this is for?
Also what building it is going from and where to.
Are you sure you are allowed to take a powered cable along the route you are thinking of in this 'public domain'
Has the socket got RCD protection?
Why an extension lead for a permanent installation?

With the info I have up to now, I would not use the cable you have suggested.

 

[Jay81]

No problem, here are some answers.

It's to power a simple digital audio player that runs off 6V. At most, the 2W internal amp will draw 200mA.
It is going from one room in a museum to another.
The museum suggested the cable trail so assume it's ok. Apologies, I guess I didn't really mean 'public domain', but a place where the public go!
There is no RCD protection on the socket but I assume they have the appropriate fuses.
The installation needs an extension lead due to available funds and the fact that the building is protected. Thanks Spoon!

 

[Spoon]

Hi Jay, This is making more sense now.
Sorry what a meant was does the circuit that the extension lead will be plugged into have RCD protection?
The route you are planning to place the cable, can the public touch it?
Is there anything to stop a member of the public from unplugging the extension or switching it off?

 

[Jay81]

No problem, I'm unsure about RCD to be honest, I'm not even sure the museum would know!
A small part of the cable may be in reaching distance but I doubt very much anyone would touch it. There are cables tacked to walls all over the place so this cable won't stand out.
As it stands there is nothing to stop the public unplugging or switching it off but again I doubt very much this would happen. Of course, worse case scenario is definitely wise but if it's not a major issue maybe there's compromise? Maybe I can make up a box to shield the power point if need be.

 

[Spoon]

I was hoping the socket may be in an office that was not accessible to the public. Then that would solve the problem. You will have to switch the supply off and isolate it if there is a problem. Keep this in mind if making a box.
There are sooooooo many thick people about that think they can do whatever they like, and if they get injured they can sue for compensation. I wouldn't just tack cables to a wall that are within reach of the public. I would protect the cable.

 

[Jay81]

Thanks Spoon, much appreciated. I guess that's a dialogue I can have with the museum. If you think the cable I suggested isn't suitable, is there something you can recommend? It doesn't have to be massively durable, just safe. Don't want to cause any fires! I'll be doing a few other installations too but this will be the longest trail by far.

 

[Spoon]

Now I know what you are using it for and where it is being fitted then I would go with Richards info in post 5. I was initially concerned the cable would be going outside across a field or something.
If possible put any cable that the public can touch in conduit.

 

[Jay81]

Great, fantastic. Many thanks for your help!

 

[Flanders]

If the socket you are plugging into is not rcd protected then i would get an exstention lead with a rcd built in or get a rcd adapture plug that way if the cable does get damage and a somone touches a live part of it the rcd should prevent them from getting an electric shock

 

[Jay81]

Great, thanks Ned I'll add that in.

 

[Spoon]

If the socket you are plugging into is not rcd protected then i would get an exstention lead with a rcd built in or get a rcd adapture plug that way if the cable does get damage and a somone touches a live part of it the rcd should prevent them from getting an electric shock

You still get an electric shock even if the circuit is protected by an RCD, they just reduce your chances of being killed by it.

 

[Jay81]

Thanks for the clarification Spoon