Shed socket

[Seventies man]

Hi,
Today I tried to put a twin socket in an outside shed. What I did was..
1. Broke into an existing ring using a junction box
2. Ran about 40 metres of 2.5mm twin and earth from the house to the shed.

The reason is I want to run a dehumidifier in the shed.

However while one of the family was using our electric shower the shower MCB tripped. Oh God! I thought, what have I done!!

Questions:
1. Is this a case of drawing too much power from the mains? (shower and dehumidifier running together)
2. Is the cable okay at this distance and does it need to be placed in conduit?

Any help appreciated!

 

[ColJack]

for a start the shower should not be on the ring main.. it needs it's own circuit..

if it has it's own circuit already then I'll asume it was the RCD that tripped..

twin and earth is not suitable for this application unless you put it in an earthed metal conduit and I doubt you have to tools to install that properly.


you should have put the run in with (preferably) 4mm armoured cable made off with proper armour glands and the armour earthed..
burry it 600mm deep ( twice the depth of a spade ) if it runs in an area likeley to be dug at any point, or clipped at 18 inches off the ground if it runs along a wall ( to stop the lawnmower etc damaging it.. )

 

[ricicle]

burry it 600mm deep

Steady on, 450mm is the recognised minimum - don't give the poor fella any extra work to do than is necessary...

 

[ColJack]

since there is no official depth mentioned in the regs, and I was always told that it was 2 spades depth, then that's what I told him..

it's better to be too deep than not at all..

the "accepted" way as you put it is 450, on a bed of sand ( so that already reduces it to 400.. ) then more sand ( another 100mm ) then warning tape..

that puts the tape at spade depth..

to be fair though, the last trench that I put cables in was 6 years ago and was 5 foot deep and 6 feet wide.. ( we were putting in mains to a hospital extension.. 8 big cables spaced about 8 inches apart.. )

 

[julioarca]

since there is no official depth mentioned in the regs, and I was always told that it was 2 spades depth, then that's what I told him..

it's better to be too deep than not at all..

the "accepted" way as you put it is 450, on a bed of sand ( so that already reduces it to 400.. ) then more sand ( another 100mm ) then warning tape..

that puts the tape at spade depth..

to be fair though, the last trench that I put cables in was 6 years ago and was 5 foot deep and 6 feet wide.. ( we were putting in mains to a hospital extension.. 8 big cables spaced about 8 inches apart.. )

How big is a spade, is it a standard size. Marker tape only required for regional electric board cables, not a requirement for own cables.
450mm is the required depth.

 

[saxondale]

How big is a spade, is it a standard size. Marker tape only required for regional electric board cables, not a requirement for own cables.
450mm is the required depth.

ahem - required MINIMUM depth

 

[ColJack]

please fix your quote saxon.. wasn't me..

and reg 522-06-03 states... ( paraphrasing.. )

unless it's in a conduit or duct ( no mention of steel.. ) for mechanical protection, then it's got to have an earthed metal sheath or be insulated concentric cable.. Buried cables, conduits and ducts shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shal be suitably identified ( ie orange plastic duct. etc... ). Buried cables shall be buried at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground

 

[briwire]

If it is 40m long plus the length of cable in the ring, there is a chance that the earth loop impedance would be so high as not to trip the 32A ring fuse/MCB in the recognised time, regardless of the fact that it might be protected by an RCD.

I think you should take it out of action immediately and get it done properly.

The correct size cable needs to be used to allow for volt drop.

It needs to be properly protected and installed.

It needs connecting in the CU properly, with the correct protection.

 

[ebee]

If you dig 20" min trench.
Place sifted sand down.
Place armoured cable .
More sand.
fill another 4" or 6".
Place warning tape/bricks.
fill level.
That way your cable is snug at 18" (450mm) from top of cable.
Should satisfy requirements.
40M of 2.5 will have volt drop & EFLI considerations.
Spurs off rings are meant to be short.
Could it not be run direct on CU as its own circuit and with thicker cable?
If it`s likely to be used outside it should be 30mA RCD protected which in theory takes care of the EFLI implication in itself but it`s far better not to rely soley on this if possible.
It`s probably notifiable too.
Get a pro to do it would be my advice.

 

[ColJack]

profile says he's in ireland, so part P not an issue..

 

[ban-all-sheds]

profile says he's in ireland, so part P not an issue..

No, but all the other ones are, like safety of buried cables, fault loop impedance....

 

[ColJack]

never said they didn't...

i was refering to the second from last line in ebee's post..

It`s probably notifiable too.

I thought you weren't posting anymore anyway...?

can't stay away from us can you?

 

[saxondale]

please fix your quote saxon.. wasn't me..

and reg 522-06-03 states... ( paraphrasing.. )

unless it's in a conduit or duct ( no mention of steel.. ) for mechanical protection, then it's got to have an earthed metal sheath or be insulated concentric cable.. Buried cables, conduits and ducts shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shal be suitably identified ( ie orange plastic duct. etc... ). Buried cables shall be buried at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground

damm shift button - it wasnt you

 

[ColJack]

are you going to edit the post then or what?

 

[saxondale]

are you going to edit the post then or what?

didnt realise I could still edit after so long - have another look