lighting bollards

A 200m drive leading to a house has lighting bollards every 10m . The zs from the last bollard is 28 ohms  this is to high for the protective device, can  i just fit 30ma rcd protection and will this satisfy the ECR 

And how would the rcd protect the circuit from a L-N short circuit?

What size is the cable?

2.5MM SWA

I've just put in a 35mm cable to supply garden lights at 170m to the distribution point.

What type of lamps are fitted? Is the last light even working?

wonder what the volt drop on that is.... 12v lamps at the end?

So much fail!

RCD's cure everything it would seem.

So many questions, Is it a TT system? Did you carry out a L-N loop test? If so what did you get? What was the R1+R2 reading? Did you take a R1+RN reading?  Have you checked the terminations where they are easily accessible such as the board/switch? 

Well,if it was me I would be testing at the source first

test lighting run second

measure "assumed" length of cable

do,a,couple of sums and see if the theoretical answer was same as measured one

dont just think ."oh that's it so it must be ok"

just saying

kerching said:

Well,if it was me I would be testing at the source first

test lighting run second

measure "assumed" length of cable

do,a,couple of sums and see if the theoretical answer was same as measured one

dont just think ."oh that's it so it must be ok"

just saying

Click to expand...

Thats the trouble with you 'new' boys, always looking to impress with your newly acquired mathematical skills, whatever happened to plug and play test instruments? 

Sorry think i got reverse polarity there! 

STRING said:

A 200m drive leading to a house has lighting bollards every 10m . The zs from the last bollard is 28 ohms  this is to high for the protective device, can  i just fit 30ma rcd protection and will this satisfy the ECR 

Click to expand...

I would be very interested to see your calculations for this circuit. Because I think 200m of 2.5mm SWA will have an R1+R2 of 2.96 ohms. Which means either; you have a TT installation which would already have some RCD protection, (I assume), or someone's got a bad joint, or someone has really installed over 1800m of cable to get such a high reading. Please tell us your dead test calculations? I think there has been a clanger dropped here somewhere?

Doc H.