Earthing help!

[batty]

Don sounds like you have volt drop problems on main cable. What is voltage at dis boards. I did a farm install a while back supply cable was 4 core 95mm swa as run was 350 mtr. What is actually being use load wise. With the lighting that also could be volt drop problems on the cabling if they are long runs. But I am only guessing.

Batty

 

[Andy™]

dont forget you only have 3% on lighting... so if your running at 2% on your final circuits, it doesnt leave much on the submain!

 

[green-hornet]

The stables may come under the agricultural regulations as well need to check with the local authority.

The supply over 250 mtrs on a 25mm swa is a little undersized.

If demand was placed at 80amps you would need a 35mm cable to allow for volt drop.

Next cable size up from that would be 50mm.

You would need to TT each building, it would be impractical running earth cables back from each board to the main met, and the main bondings would have to go directly to the main met.

Even when using swa as earth, I always run a seperate 16mm earth to each db and thats when in the same building.

Buried cables will have to be ducted or the size would increase for the earth cables to at least 25mm maybe more not looked at the BRB.

 

[D Brennan]

Don sounds like you have volt drop problems on main cable. What is voltage at dis boards. I did a farm install a while back supply cable was 4 core 95mm swa as run was 350 mtr. What is actually being use load wise. With the lighting that also could be volt drop problems on the cabling if they are long runs. But I am only guessing.Batty

was only first day there today but when i took a reading on the switch live at the furthest light i was getting 217v but on the same light at p live i got 235v, to be honest there is a lot already connected but very little will be used at the same time, at present it has been tempory connected on 1 phase and all has been running ok ie not blown main fuse as yet with both building on, i need to investigate it all properly on monday when the cherry picker comes on site before i do any work i have been asked to do.

The job may be cursed, i am the 4th electrician and the other 3 have died, so there is a mixture of different peoples wiring, but whatever needs to be done will get done..... the customer has spent 6 million so far on the place inc all the land so my bill will be small change i hope

 

[Andy™]

The job may be cursed, i am the 4th electrician and the other 3 have died,

are you sure you want to work there?!

 

[D Brennan]

are you sure you want to work there?!

ha ha lads i have giving me a lift were saying that today, got me thinking...but cant be turning nothing down in these ****e times

 

[green-hornet]

was only first day there today but when i took a reading on the switch live at the furthest light i was getting 217v but on the same light at p live i got 235v, to be honest there is a lot already connected but very little will be used at the same time, at present it has been tempory connected on 1 phase and all has been running ok ie not blown main fuse as yet with both building on, i need to investigate it all properly on monday when the cherry picker comes on site before i do any work i have been asked to do. The job may be cursed, i am the 4th electrician and the other 3 have died, so there is a mixture of different peoples wiring, but whatever needs to be done will get done..... the customer has spent 6 million so far on the place inc all the land so my bill will be small change i hope

I never like to follow on a job.

I normally bill them for testing out, to see if I can re use any materials.

Loads of sparkies just jump in without doing any design work or calculations.

Some tempory installations become permanant simply because they are there and work.

I would do a full test and inspection, tell the clients what they are up against and then do all the calcs for the supply and distribution.

When you know what your up against you can go to them to tell them what needs doing and why.