Extending power to second shed

[petej42]

Can anyone advise me on what cable to lay between an existing shed and a new one.

The current shed is supplied from a separate circuit on the house consumer unit, the current armoured cable is about 45 meters in length and is marked as 3 X 6.0 and runs to a small consumer unit in the shed. I wish to lay a cable from this shed to the site of another about 15 meters away. The power consumption on the new shed wouldn't be more than 15 amps and the existing shed is used mainly for lighting an the odd garden tool.

The consumer unit in the shed has a spare connection, but I will be getting qualified electrician to connect to this when the time comes. I just want to lay a cable as I need to tidy the garden where the cable will run. I do have some 3 core 1.5mm armoured cable left by the previous owner, but I don't know whether this would suffice.

Any advice would be greatly appreciated

Pete

 

[Taylortwocities]

You would need to work out the volt drop to see if it is within limits. Bearing in mind the length for CCC purposes will be the original 45 metres plus the added 15.
A job for your electrician but off the top of my head I would guess 1.5mm ain’t gonna be big enough.

 

[Tommyplug]

Can anyone advise me on what cable to lay between an existing shed and a new one.

The current shed is supplied from a separate circuit on the house consumer unit, the current armoured cable is about 45 meters in length and is marked as 3 X 6.0 and runs to a small consumer unit in the shed. I wish to lay a cable from this shed to the site of another about 15 meters away. The power consumption on the new shed wouldn't be more than 15 amps and the existing shed is used mainly for lighting an the odd garden tool.

The consumer unit in the shed has a spare connection, but I will be getting qualified electrician to connect to this when the time comes. I just want to lay a cable as I need to tidy the garden where the cable will run. I do have some 3 core 1.5mm armoured cable left by the previous owner, but I don't know whether this would suffice.

Any advice would be greatly appreciated

Pete

my quick calculation makes it to small for 16A braker but ok for a 10A

 

[Taylortwocities]

Tommy, he’s after the cable size, not the CPD value!

 

[Tommyplug]

Tommy, he’s after the cable size, not the CPD value!

sure he is. i was pointing out the cable is ok for 10a if thats enough for his use.

 

[ban-all-sheds]

I will be getting qualified electrician to connect to this when the time comes.

The time to get a qualified electrician has already come, as it has to be she who designs the circuit, and at least specifies the way it is to be installed, as only she can sign this (with the significant part highlighted):

I being the person responsible for the design, construction, inspection & testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design, construction, inspection & testing hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2015 except for the departures, if any, detailed as follows:​

 

[ban-all-sheds]

Tommy, he’s after the cable size, not the CPD value!

I do have some 3 core 1.5mm armoured cable left by the previous owner, but I don't know whether this would suffice.

Seems fair enough to comment on the existing cable.

 

[Taylortwocities]

Seems fair enough to comment on the existing cable.

Err. OP has said the design current for the new shed is 15amp. How can a cable that is "OK for 10amp" be a great suggestion?
Even if it were big enough, which it isn't.

 

[ban-all-sheds]

Err.

A: "I need a cable to carry no more than 15A, to supply lighting and sockets for garden tools in a shed. I have some cable already, but I don't know if it will suffice."
B: "The cable you already have is good for 10A, if that's enough for your lights and sockets."

Not sure why you're finding this so confusing.

Even if it were big enough, which it isn't.

We don't know that.

We don't know what the load will really be, but we do know:

1. 1.5mm² SWA is OK for both fault and overload protection on a B16
2. Depending on the loads in the first shed (quite possibly zero if the second shed is in use), end-to-end volt drop for the actual load in #2 might be fine (possibly qualified by "in practice")
   
3. An electrician is needed to establish the actual design parameters

 

[DetlefSchmitz]

The simple answer to the OP is to use a flexible duct and a draw-string. Preferably bring it up inside the buildings concerned. It can then be covered up, and decisions about cable size etc made later. Take photos before filling the trench to show the electrician.

 

[petej42]

Thanks for the comments everyone, looks like I may have to get an electrician in.
Wasn't planning to do this until next year when the new shed was to be erected, but looks like I may have no choice.

Is there a possibility that the extra 15 metres of cable would be larger gauge than the existing 45 metres (I e. 6mm)?

The power in the second shed is to drive a telescope mount, camera and gear each of which need a 12v regulated supply. The mount is rated at 7 amps, camera 1.5 amps and other gear maybe 2amps so the 15amps in my earlier post was to provide some contingency.

The idea of ducting and a draw string is unfortunately not practicable as the wire will need to go through a couple of 90 degree turns before going into the existing shed, one of the reasons I wanted to lay the cable early was that I currently have access under this shed to feed the cable through.

 

[Tommyplug]

Thanks for the comments everyone, looks like I may have to get an electrician in.
Wasn't planning to do this until next year when the new shed was to be erected, but looks like I may have no choice.

Is there a possibility that the extra 15 metres of cable would be larger gauge than the existing 45 metres (I e. 6mm)?

The power in the second shed is to drive a telescope mount, camera and gear each of which need a 12v regulated supply. The mount is rated at 7 amps, camera 1.5 amps and other gear maybe 2amps so the 15amps in my earlier post was to provide some contingency.

The idea of ducting and a draw string is unfortunately not practicable as the wire will need to go through a couple of 90 degree turns before going into the existing shed, one of the reasons I wanted to lay the cable early was that I currently have access under this shed to feed the cable through.

is that 7a at 12v? 1.5a at 12v? 2a for extras at 12v?
if it is 10.5a total at 12v thats 126w or under 1a at 230v allowing for loses

 

[petej42]

Oops, forgot laptop, say 20v 4amps.
Just rechecked the amperage on the other items and the figures do seem right. A couple of dew heaters may be needed in the future at about 10 amps total but still only 12volts

 

[ban-all-sheds]

The simple answer to the OP is to use a flexible duct and a draw-string.

2 ducts:

laptop

1 for power

1 for data

Wireless should only be used when there really is absolutely no alternative.

 

[ban-all-sheds]

Is there a possibility that the extra 15 metres of cable would be larger gauge than the existing 45 metres (I e. 6mm)?

Not really.

If you want to play with numbers: http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

Specify 2-core cable and PVC, even if that is not what you are using or it will make invalid assumptions.