SWA & Fly Lead

VMan · Jul 9, 2011

ok guys, not done much work with swa, so here's a simple q for ya'll.

Im putting a Submain into a garage, with isolator next to main DB (inside house).

First off, i will run 4mm 3 core SWA, being routed through brick wall and run horizontally to garage, direct clipped to wall. do i need a drip loop on outside wall? ( I think so? but hope not!

hone

SWA will terminate into isolator (inside building) and then use 4mm T+E to spare fuseway in DB.

2nd, Q, as one core will be cpc, when i terminate the SWA in the isolator, should i link together the SWA with the CPC using a fly lead?
And this only needs to be done on one end of the SWA, i.e no need to link SWA to CPC lead in garage, if done in house?

i have read posts where it should be bonded and run its own bonding conductor, but cannot see wy this is necessary.

Thanks in advance

v

telectrix · Jul 9, 2011

drip loop not required if hole in wall is sealed. i would earth the armour at both ends so as to utilise the armour as additional earth conductor.

malcolmsanford · Jul 9, 2011

I personally would not have a drip loop in it, just make sure that you seal where the SWA exits the hole to make sure that dampness can not creep back into the cavity.

Yes just earth the SWA at the origin as you said. Bonding is different if you have a service ie water or the garage is of metal construction, then if your exporting the house earth, you need to bond the service/metalwork back to the main MET at the house. Is the garage detached?

telectrix · Jul 9, 2011

i was thinking of using the armour as additional earth as he's ony using 4mm core. agree with bonding extraneous back to MET ( unless of course he's going to TT the garage.) . no, not going into exporting pme! LOL.

Dunc · Jul 9, 2011

Never really bother with drip loops but i always drill the whole from outside to inside at an upwards angle and seal with silicone. Belt and braces method as water tends not to travel up hill.

VMan · Jul 9, 2011

Garage is attached, cables seem to run through ceiling, and i cannot find any other way of internally running the cables, plus customer happy with them running outside.

So just to confirm:
- i got 4mm T+E from DB to isolaor (<0.5m run)
- From Isolator i got SWA going to garage.
In the isolator i can just link the CPC from SWA, and SWA together to the CPC of the T+E?? or should i run a 4mm 3core flexi to keep the 4mm CPC all the way through?

hmmm.. I think ill use 3 core flexi instead of the T+E, i'll do my R1+R2 without the SWA connected, then my Zs with the SWA connected, that way i can be sure the CPC is Adequate...This sound good?

thanks guys

Dunc · Jul 9, 2011

What is the existing consumer unit made of? Just wandering what the isolator is for unless you mean a second consumer unit due to no space in the existing or it's an old timber Wylex board. If it's a plastic or metal CU with enough depth in the top or side walls just gland the SWA straight in to the CU and use a Piranah nut to earth the amouring. Alternatively use a similar method but gland in to a small adaptable box. Stick a grommet in the other side of the box and pull the inner part of the SWA and a earth bond through in to the CU. Much easier way of doing it and cheaper then buying an isolator if you don't need one.