Earthed metal conduit vs SWA

[Cigarshaped]

My shed has been supplied via 3 core PVC round (16A?) cable through galvanised iron water pipe for 25 years. The circuit currently runs as a spur off the RCD-protected 13A ring. I assume this is still legal but I need to bond the metal to earth? Can I use the normal earth bonding straps in partially exposed conditions such as this? How far back does the bond wire need to go?

Alternatively I need to go the SWA route and need to know at what point in the circuit do I interface the armoured cable with normal T & E PVC. Is there a favourite type of box to do this? We have an excellent glass canopy at rear of house but I guess the house brick wall still remains the boundary between in and outside?

 

[ban-all-sheds]

My shed has been supplied via 3 core PVC round (16A?) cable through galvanised iron water pipe for 25 years.

Just waiting for someone to mistake it for a water pipe.

And is it dry and watertight, or is that cable in water some or all of the time?

The circuit currently runs as a spur off the RCD-protected 13A ring. I assume this is still legal but I need to bond the metal to earth?

It's not bonding, it's earthing.

Can I use the normal earth bonding straps in partially exposed conditions such as this?

"Partially exposed"?

How far back does the bond wire need to go?

To a convenient place to connect it to the cpc of the cable within it.

Alternatively I need to go the SWA route

Don't look on it as an alternative - look on it as what you should use to replace the current unsatisfactory arrangement.

and need to know at what point in the circuit do I interface the armoured cable with normal T & E PVC.

Wherever convenient, taking account of the fact that T/E should not be run outdoors without protection.

Is there a favourite type of box to do this?

A metal one. Proof against leakage and corrosion if used outdoors.

We have an excellent glass canopy at rear of house but I guess the house brick wall still remains the boundary between in and outside?

That's usually a convenient place.


Also: //www.diynot.com/wiki/electrics:part-p

 

[Cigarshaped]

Thanks ban-all-sheds, I wonder how you picked that name?

And is it dry and watertight, or is that cable in water some or all of the time?

It is sealed at upper end with elbow 1 ft above ground and on a slope.

Can I use the normal earth bonding straps in partially exposed conditions such as this?

"Partially exposed"?

The lower (house) end of pipe is just under canopy. Are EARTHING straps weather proof?

Wherever convenient, taking account of the fact that T/E should not be run outdoors without protection.

I have use square trunking and round conduit for the external wiring so far, under waterproof glass canopy.
I do intend to have electrical system checked soon - we may be having a front extension - so I guess it all has to pass part P?

 

[rebuke]

Read the wiki, it has plenty of info on Part P, to summarise though - ALL electrical work must comply with Part P, and certain work (including outdoor electrical work) is classed as notifiable, so you need to notify the LABC before doing the work, unless you are a member of an approved self certification scheme...

 

[ericmark]

How ever much we try to envisage what you have we are likely to make errors when trying to advise remote from the location.

The IET (Was IEE) have a publication which may help The Wiring Matters 2005 has Electrical installations outdoors: a supply to a detached outbuilding in PDF format which although slightly out dated is near enough for most of what you need.

Water pipe being a heaver gauge than wiring conduit was often used to protect cables and it would take far more effort to penetrate water pipe than conduit or SWA cable.

However with both conduit and water pipe rust can cause both pure bad connections and semi-conductor junctions with could mean the earth is not as it should be and it could cause radio interference although unlikely.

So best option is for it to be tested. The meters required are expensive and also if used incorrectly there is some danger. So I would suggest you get a local electrician to inspect and test before you go to what may be unnecessary expense.

As long as he is registered under the Part P if any small additions are required he could do then and document so keeping everything legal as well.

What BAS says could be true and I am not in anyway saying he is wrong but he like me are only guessing at what is really there and it also could be a good install with all the required tapes and tiles for ID buried cable.

 

[ColJack]

BAS isn't against garden sheds, he's against the large DIY warehouses, which we sometimes refer to as the DIY sheds..

 

[Cigarshaped]

Thanks guys
To wrap this up:
1. A friendly electrician is coming to check my handiwork.

2. The shed interior is fitted out in 20mm conduit - I wonder if it matters if Red & Black cabling instead of Brown & Blue....? Recycling is good for the environment ain't it?

3. Earthing straps are available for EXTERIOR use. I found Wolsley Electric Center very helpful - much better than using the 'SHEDS'.

 

[ban-all-sheds]

1. A friendly electrician is coming to check my handiwork.

Is he friendly enough to lie on electrical certificates and notifications to the council that he did the work?

2. The shed interior is fitted out in 20mm conduit - I wonder if it matters if Red & Black cabling instead of Brown & Blue....?

It doesn't, but many electricians think it does - maybe your friendly one is one of those.