uHeat Banner - Forum Discount Available
This official sponsor may provide discounts for members
Advertisement - Content continues below
Advertisement - Content continues below

Discuss Does this metal post need to be earthed or bonded or neither? in the Electrical Forum area at ElectriciansForums.net

happyhippydad

-
Arms
Esteemed
Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

I have 5 x 6m metal posts sticking out of the ground used for 200w floodlights to light up a manege.

This is a domestic stables. The posts test as 35ohms to earth. The installation is TNCS and has 30mA RCD protection on all circuits.

The floodlight will be earthed and in doing so the post will become earthed as the bracket holding the floodlight to the post is metal.

I just cant quite work out if the post is an extraneous conductive part and needs a 10mm bonding cable or if it's an exposed conductive part as it's housing the cable up the middle of it and is holding the light, in which case it is earthed, however is the 1.5mm earth feeding the floodlight sufficient.

The cable feeding the arena lights is 6mm 3 core SWA.

Just when i think I've got earthing and bonding completely sussed I get a situation that confuses me!
 
Advertisement - Content continues below

James

-
Mentor
Arms
Supporter
Esteemed
ok, so the post on its own is no risk to anybody.
just a metal pole sticking out of the ground.

there is no risk of someone being in contact with the earth to light fitting and a different potential earth from the post itself.
I presume the circuit is rcd protected?

personally I cant see an issue.
it would seem ridiculous in my mind to bond the posts with a 10mm cable.

I am happy to wait for constructive criticism if my interpretation is incorrect.
 
I'd say it would be an exposed conductive part at most as it's forming part of the electrical system. but if unsure IR test to earth and if greater than 0.02mohms it's just a piece of metal
 

happyhippydad

-
Arms
Esteemed
  • Thread Starter Thread Starter
  • #5
I'd say it would be an exposed conductive part at most as it's forming part of the electrical system. but if unsure IR test to earth and if greater than 0.02mohms it's just a piece of metal
It's measured 35ohms to earth so just a tad under 0.02Mohms :)
There is a weatherproof junction box 40cm above the base of the post (attached to the post) which houses the terminations going up to the floodlight and on to the next post.
 

AJshep

-
Arms
Esteemed
Advent Win
IMO as long has it has a connection to a cpc and the entire length of the cable that is in contact with the pole is 30mA rcd protected. you don't need to take a main bond to it..

If it wasn't RCD protected before coming in contact with the pole then it would require bonding.
 
IMO as long has it has a connection to a cpc and the entire length of the cable that is in contact with the pole is 30mA rcd protected. you don't need to take a main bond to it..

If it wasn't RCD protected before coming in contact with the pole then it would require bonding.
If the metal work becomes live due to a broken PEN conductor how will an RCD affect the outcome ?

In my opinion you should insulate the physical connection between the floodlight bracket and the post .
 

Lucien Nunes

-
Mentor
Arms
Esteemed
By connecting the TN-C-S earth to the post, you could create a voltage gradient from the post across the soil, since the TNCS PEN could be a significant voltage away from true earth. It won't be much of a gradient because of the low Ra of the post, however horses are very sensitive to voltage gradients. It might be better to isolate the post and/or fitting from the supply earth.

Post crossed with Jim's
 
T

Toneyz

Without checking I think that when you do lamp posts the minimum to earth the post is 6mm.
 

Midwest

-
Arms
Esteemed
Section 714 outdoor lighting, 714.411.203 (BYB), applies I think. As its for stables, I'd also have a look through Section 705.
 
Test Meter - Forum Sponsors since 2007!
This official sponsor may provide discounts for members
Advertisement - Content continues below

Reply to Does this metal post need to be earthed or bonded or neither? in the Electrical Forum area at ElectriciansForums.net

Electrical2Go - Online Electrical Supplier
This official sponsor may provide discounts for members
Advertisement - Content continues below
Advertisement - Content continues below

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
Advertisement - Content continues below
Top Bottom