BOND YES OR BOND NO - DO I BOND THAT OIL TANK - OR THAT WATER PIPE - AN EASY CALCULATION FOR SAFETY
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- Опубліковано 10 лют 2023
- In this LearnElectrics video we will take a simplified look at what we can do when we need to make a decision about equipotential bonding of conductive parts that are not part of the electrical installation.
This is an important consideration for any electrician. Customer safety is paramount and the last thing we want to do is to introduce sources of electric shock hazard where none existed before.
We’ve had a few questions recently, asking how one decides if external oil storage tanks need to be bonded, or copper water pipes that enter the house by plastic service pipes should be equipotential bonded.
If the resistance path to Earth is sufficiently high enough, then equipotential bonding may not be required. But just what is this resistance figure. How can we calculate the correct figure for any particular situation.
It’s an easy calculation that gives you confidence that you are doing the right thing to keep the installation, and the user, safe.
To view all of our videos type in LearnElectrics all one word into the UA-cam search bar.
This is video No.184 on our UA-cam channel where we have videos on a wide range of electrical topics.
Thank you, as always, for guiding those of us mathematically challenged gently through this topic. Much appreciated.
Agreed mate, I really struggle with maths but dave explains things so well 🙌🏻🙌🏻
My pleasure, I was in the same predicament many years ago. It does get easier. Dave.
Thanks for the great support. I try my best for you guys. Dave.
Just seen your channel has had over 2.3 million views. So well deserved its helped so many people
Thank you, great comment and appreciated.
Another great educational video guys. What would I do without you!!! Thanks!
Happy to help and glad you found it useful. Thank you.
Fantastic information. Explained really well thank you very much
Glad it was helpful Ben. Thank you.
Great video. Thank you
Thank you, nice feedback and thanks for watching, Dave
excellent, thanks for the video
Glad you liked it, thanks for the support.
Perfect explanation mate. Learn more from you than at college.
Glad to help, lots more to come.
Awesome!
Thanks, appreciated.
Great channel, it'd extremely helpful, keep it up
Thanks, will do. Thanks for the support.
Excellent video, very well explained, thank you.
Glad it was helpful and thanks for the support. Dave.
Amazing explanation 👏 thankyou for the great videos.
My pleasure, thanks for watching, appreciated. Dave.
brilliant again 👌
Thanks for watching Brian, and for the support. Dave.
Superb as always.explained we'll always learning 👌cheers
Thank you Martin, great comments. Dave.
It would have been a great video if the mechanism by which bonding or not bonding causes shock picturially, then follow all the above video, like how a path for current to flow to the oil tank comes from and how that path possibly cause shock, lets say it come from the house through the ground to the tank then it has got to return to the house, if someone touches the oil tank nothing will happen and does touching the ground at some point go to the oil tank, or the oil tank already have live hot wire......
Thanks for watching. Appreciated.
If you don't have a multimeter, you can usually carry out the higher resistance measurement with an insulation tester / multi-function tester set to 250V, or 100V if it has it.
Thanks for watching, appreciated.
A great video this is.
Imagine this.A metal diesel tank is next to metal grain silos that are earthed.the fuel tank itself is not earthed or bonded but it's feet may be earthy.would it good practice to bond the tank or just leaving it alone Is? regards
A lot depends on how close they are and what resistance readings you get.
Very Use full information Vdo Sir
In above case U0:230 some consultant take value 50Volt ,why it is so any reason for that which value needs to be taken
Are you are confusing touch voltage (50V) with Line voltage (230V).
Veey good vdo sir
While measuring resistance between oil tank and MET ,the DNo earthing conductor is removed or it is intact with MET.
It can be left in place. Thanks for watching.
Wish you could do a series about electrical portfolios.
On the list.
Brilliant video. One question i have. Where does touch voltage come into this situation? As in minimum touch voltage allowed is 50 volts.
Its the voltage that might be there, between your feet touching the ground potential and your hand touching a grounded structure. In certain circumstance, there can be a difference in potential between your feet and your hands, especially when an earth fault occurs.
@@learnelectrics4402 yes, well explained. So touch voltage is just a general rule of thumb, so to speak? As in a bathroom containing a shower. 1667 ohms ÷ by 50 volts = .03 milliamps, so rcd will trip as bathrooms are protected by RCD'S, but 1667 ohms ÷ 230 volts= .13 of an amp, so .13 amps is leathal!! My point been that not all circuits are RCD protected, so the latter calculation is more dangerous. If you get what i mean!!
I was told you can IR between the main earth and the conductive part and if it’s over .03M no need to
Bond. Does this sound right?
Is it an exposed conductive part or an extraneous conductive part?
Look at Reg 411.3.1.2. ... liable to introduce a dangerous potential difference and then decide if your test method will identify this. Hope this helps.
Never mind the calculations keep it simple show us how to measure with our fluke multi tester and explain what readings to look for going about premises with long wander lead R2 and touching on pipes example if it’s over 10 ohms does it need bonded is it safe Thanks. Davie
Thanks for watching. If its ten ohms it definitely needs bonding. Have another watch of the video, it does explain how to decide. Dave.
If I use my wander lead in bathroom touching on all pipes including radiator pipes what would the reading be if the copper pipes are connected to plastic outside the bathroom and it would be safe not to bond any pipes no rcd in CU
Sir can add vdo on Bonding and Earthing practical for above case
Have a look at our video on testing bonding on this link ...
ua-cam.com/video/wYsYBE-MXzQ/v-deo.html
Great video as ever Dave, one query though. Is it correct to test an Rcp value from the metalwork in question, to a FULLY CONNECTED main earthing terminal (with all the cpc’s and other bonding in place)?
Some guidance recommends to test to the disconnected “earthing conductor” and the exposed metalwork in question?? As you could be getting a fortuitous low reading through a parallel paths
This is testing between the oil tank (say) and the MET before you make any bonding connections to it. You might be getting confused with testing the bonding cable when you do disconnect.
Here there are no cables going to the oil tank and we are deciding if we should bond or leave it without bonding.
Hope this helps.
@@learnelectrics4402 yes the scenario I’m describing is perhaps during an eicr. Where say the water is bonded and final circuits, with their CPC’s are connected to the met. Then you may have a concern about if a metallic oil tank needs bonding. So in this instance would you say best practice is either for all parallel paths to be removed, or just test to a disconnected earthing conductor and the oil tank in question?
@@gbelectricks The resistance would be lowest if all the parallel paths are connected, so wouldn’t it be better to know the lowest resistance between the oil tank and the MET as this is when the current would be highest.
@@jonbailes1934 how about if the water bond is connected (at stop tap and MET) then the water pipework glands onto a boiler manifold next to the boiler oil pipework. You could falsely read a low RCP resistance through the connected oil pipe onto the water pipe then back to the MET via the water bond. Surly the rcp measurement should be made onto the metallic oil tank with parallel paths isolated??
@@gbelectricks I’m no expert on this but it just seems to me that if all of the bonding is removed you can measure the true resistance between the MET and the oil tank. That’s great as you can calculate the current and risk assess accordingly. However, if you then reconnect the other bonding elements, Rcp will decrease if they are in parallel so your current will increase and your risk assessment may be invalid. That’s why I think it’s better to use the worst case low resistance readings to calculate the currents. As I say I’m no expert and I am probably missing something!
👍👍
Thanks for watching, appreciated.
Would that be an insulation resistance test
We are talking about continuity tests, low ohms resistance, here. Thanks for watching. Dave.
Dave, by having an RCD or RCBO protecting the circuit, does this whole issue become inert ?
Mike, the Regs still require bonding to be provided. Thanks for your support. Dave.
@@learnelectrics4402 Thanks Dave, got me thinking. Looking a bit deeper I can see that at 10mA most people cannot release themselves from the shock and a 30mA RCD will not be stimulated enough to disconnect. However, in a fault where an exposed conductive part has become live and the cpc has failed to activate ADS, on human contact this would surely trip an RCD, thereby removing the risk of a living thing bridging between the exposed and extraneous paths to earth ? I guess prior to RCDs, bonding was the only method to remove the potential difference and is arguably more reliable, provided it’s maintained. Is it a case of belt and braces ?
No, an RCD does nothing in case of aPEN fault.
@@okaro6595 Good point, thank you.