costing for garage instalation

[jnybakers]

hi guys
installing a garage consumer unit 30m from the main cu
it is part of my elecsa assessment.

I live in hertford and would like to know what a job like that would cost normally.
thanks.

 

[SparkyJoe]

Burrying an SWA? cable size? Time estimate? Space in the cu?

 

[jnybakers]

Burrying an SWA? cable size? Time estimate? Space in the cu?

thanks, he doesn't want to pay for digging a trench so following some advice i will put a baton across the fence and run it along that, and i will be running 6mm SWA as well as burying an earth road for a TT system for the garage since i cant take the TNC-S to the garage and it is only a 4 way CU.

 

[Deleted member 26818]

Why can't you take the TN-C-S to garage, and do you think your assessor will be happy with the baton arrangement?

 

[Octopus]

Is there bonding in place in the house?

What are you installing in the garage?

How much have you worked out the installation should cost?

Too many questions....

 

[Guest111]

don,t batten to fence it,s a bodge,if the guy won,t pay to have it buried walk away.just because others lower their standards doesnt mean you should.I walked away from a few jobs rather than bodge them.you still get grief if it goes wrong and theres loads can go wrong attaching to a fence.

 

[i=p/u]

just ly it on the ground along perimeter of fence...... rather than tack it too a fence, it will sag eventally unless cleats/clips every 100mm..

no offence, dont walk away... work wih them, talk to them bt if he tells you how to do it, say you do it

 

[jnybakers]

Why can't you take the TN-C-S to garage, and do you think your assessor will be happy with the baton arrangement?

i thought you weren't allowed to transfer the earth and that would make it a tn-s hence changing the dno's arrangement
the customer has refused to pay for digging and i believe if the fence is sturdy it will be fine, but do correct me if i'm wrong.

 

[jnybakers]

sorry i thought i put that in, it is just a 4 way cu in the garage and yes there is bonding in the house
i'm not sure about the costing, just moved to this area and reasonably new in the trade (this is meant to be part of my assessment by elecsa).

 

[Octopus]

sorry i thought i put that in, it is just a 4 way cu in the garage and yes there is bonding in the house
i'm not sure about the costing, just moved to this area and reasonably new in the trade (this is meant to be part of my assessment by elecsa).

So how much DO YOU think you should charge inclusive of all parts, certification and notification?

 

[Deleted member 26818]

i thought you weren't allowed to transfer the earth and that would make it a tn-s hence changing the dno's arrangement
the customer has refused to pay for digging and i believe if the fence is sturdy it will be fine, but do correct me if i'm wrong.

Who told you that youaren't allowed to 'transfer' the earth?
TN-C-S is a system where the network supply is TN-C, and is presented to the customer's installation as TN-S, as such you would not be altering the DNO's arrangement, becuase the DNO have already arranged it as TN-S.
However you indicate that you intend changing the DNO's arrangement to TT?
What you are not allowed to do is to use TN-C (except in rare circumstance) in a customer's installation.
You state that you intend using SWA, so you will be taking an earth to the garage, I can't see any reason why you would not use that earth.
Do you suspect that the Zs will be too high, or are there extraneous-conductive parts in the garage that would require protective bonding?

 

[Engineer54]

I think you may end up with a fair bit of explaining to do, with your assessor. You haven't explained so far what the termination and connection arrangement is at the supply end of your sub-main cable. Whether or not it's RCD protected via the main CU, or if you intend to RCD the garage CU.

Battening across the bottom/base of the fence posts, is probably your best option as far as routing of your sub-main cable, but if these posts are of the precast concrete type, your going to have problems getting fixing into them. They tend to be full of steel re-bar, so normally chunks of concrete come away as your drilling into them... . Any wood you use will also need to be treated or it won't last very long at all....
The very last thing you should do, is just lay the SWA cable on the ground unprotected from clowns with shovels and forks etc, let alone increasing the likelihood of casual/accidental damage to the cables PVC sheath!!!.

 

[reefagrim]

you havent explained much apart from distance 30m whats your load at the end of it what does the customer want to attacvh to it. do you have a set route above or below ground .. ? noy much to go on ?
find you expected load then earthing arrangement? at which point VD thermal constraints , flora and fauna ( yes i have seen a fox chew thru a swa yes it died ) if it was me i would install switch fuse iso at house only earth the sheath from the house thus making for a tt system at gargae which will get over the zs issues rcd and what ever else is required also i asume its in the country side being a garage 30m from the house take account into the local enviroment soil and such just to make sure the earthing will be correct as we are all aware the suppliers dont always get their ze readings within the recommended amounts . as for cost as for cost work out material cost and then double that for labour i bet you wont be far off the right price

 

[Engineer54]

if it was me i would install switch fuse iso at house only earth the sheath from the house thus making for a tt system at gargae which will get over the zs issues rcd and what ever else is required

Taking it, that this garage only requires a couple of sockets to power general light loads and some lighting provision, what Zs problems would you be expecting on a 30m 6mm SWA cable?? Also, what problems is he going to have with the garage RCD etc using the supply PME earthing?? Forget making this installation a TT system, far better off using the TN earthing. Nothing stopping him from banging in a decent rod and connecting it to the garage EMT!! It'll be serving as a local additional N-E point on the DNO's PME system... Not much good mind, at anywhere around the magical 200 ohms!! lol!!!

 

[jnybakers]

due to the garage being 30m away, a 30m run of 6mm swa would definitely increase the zs considerably.
and just to be on the safe side i thought an earth rod in the garage would be a better bet.