chrisg1979
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De ja vu???
Earth bonding to gas bottles
- Thread starter adammid
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Doc Hudson
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Threads merged, I suspect some of our members are more shocked that anyone undertaking electrical work cannot establish if a metal item is extraneous or not. It is a fundamental design principal of BS7671 before undertaking any alterations temporary or permanent as per regulation 132. What is your measured continuity between the alleged extraneous metal part and electrical earth? At one point you are saying they are extraneous, the next point they are not.?
Doc H.
Doc H I never said I knew the answer. I'm no expert, I just saw it and thought it wasn't right that its not bonded. I havn't carried out any tests. I'm not a spark. I thought because it's gas in a copper pipe used with electrical equipment it needs bonding. Am I right or not?
adammid,
IF it were bonded then in the event of a live wire touching the pipework a current would flow through the pipework to earth, now at any high resistance or electrically non continuous joints you would have the possibility of heating and sparking, thus you would be introducing the possibility of an explosion caused by that heating/sparking.
IF it were not bonded, the pipework would merely sit there with no current flowing if it were isolated from earth with 230V on it wrt earth. Now this poses an electric shock hazard, it also poses a fire/explosion hazard as if anything that is suitably earthed should come into contact with the pipework then this could generate a spark and again cause an explosion.
It is not quite as cut and dried as you seem to first think, in fact, this may not be an electrical issue at all!
IMHO the best way is to ensure that no live electrical conductors from the fixed installation can come into contact with the pipework in the first place!
Without greater detail on the exact installation, both gaseous and electrical, along with test values it is impossible to state whether it must be bonded or not.
If it extraneous then it should be bonded, if it is not extraneous then perhaps it does not need bonding, the same as a plastic incoming water service does not definitely need bonding when it changes to copper. This all depends on whether it is in fact extraneous.
It could also depend on the relevant gas regulations and the information given by the manufacturer/installer of the equipment. It could also depend on the electrical continuity of the joints in the pipework.
If this is "bottled" gas, e.g. Air Products, BOC etc. then it may be that you need to check the guidance issued by the BCGA, and/or check with the relevant standards covering the gas install also.
Finally for now, if the electric welding equipment is to current standards then unless the welding return lead is connected to the structure of the building then it must not be possible for the welding set transformer secondary side to generate a welding current between the electrode holder and true earth in the building. That is the welding set is fitted with an isolating transformer, if it complies with 60974.
IF it were bonded then in the event of a live wire touching the pipework a current would flow through the pipework to earth, now at any high resistance or electrically non continuous joints you would have the possibility of heating and sparking, thus you would be introducing the possibility of an explosion caused by that heating/sparking.
IF it were not bonded, the pipework would merely sit there with no current flowing if it were isolated from earth with 230V on it wrt earth. Now this poses an electric shock hazard, it also poses a fire/explosion hazard as if anything that is suitably earthed should come into contact with the pipework then this could generate a spark and again cause an explosion.
It is not quite as cut and dried as you seem to first think, in fact, this may not be an electrical issue at all!
IMHO the best way is to ensure that no live electrical conductors from the fixed installation can come into contact with the pipework in the first place!
Without greater detail on the exact installation, both gaseous and electrical, along with test values it is impossible to state whether it must be bonded or not.
If it extraneous then it should be bonded, if it is not extraneous then perhaps it does not need bonding, the same as a plastic incoming water service does not definitely need bonding when it changes to copper. This all depends on whether it is in fact extraneous.
It could also depend on the relevant gas regulations and the information given by the manufacturer/installer of the equipment. It could also depend on the electrical continuity of the joints in the pipework.
If this is "bottled" gas, e.g. Air Products, BOC etc. then it may be that you need to check the guidance issued by the BCGA, and/or check with the relevant standards covering the gas install also.
Finally for now, if the electric welding equipment is to current standards then unless the welding return lead is connected to the structure of the building then it must not be possible for the welding set transformer secondary side to generate a welding current between the electrode holder and true earth in the building. That is the welding set is fitted with an isolating transformer, if it complies with 60974.
ParkySparky
Senior Member
The 'bang' sounds nasty!
Sidewinder, thank you very much. Its appreciated. That's is all I asked for previously. I like this forum and it is full of some knowledgable ppl however their appears to be a very distinct attitude on here of 'I know more than you, you don't know what you are talking about, haha'. I don't testify that I'm an expert, hence why I came on here for advice, instead I got slated.
Oh, just re-read your op the bond may need to be 50mm sq if you were to bond, now we know it is an FE college, it may be TN-C-S, it may be PME, it may be PNB, another thing we don't know, hence my questions in my first post as a starting point.
This is not as cut and dried as it may seem.
Is the incoming supply metered at LV or HV?
This will also have a bearing!
This is not as cut and dried as it may seem.
Is the incoming supply metered at LV or HV?
This will also have a bearing!
Hi Adammid,
The problem you have, is that, as Sidewinder has explained, there are PERFECTLY good and valid arguments both for and against bonding. The best thing you can do [in order to protect yourself] is to ask the BCGA for their advice, or ask the makers of the equipment, both courses of action that Sidewinder suggested earlier.
You might find that the "experts" from the BCGA change their minds from time to time too, [as has been done in the case of arrangements for earthing welding sets..]
Best thing is to ask these people and just do what they recommend at present. Once you know what they recommend, then, if they do recommend bonding, you will have the problem of precisely how to go about this, but that is a problem for another day..
Finally, can i just say that no matter what level of experience or knowledge you have of electrical installations, i think i can speak for ALL of us on here, when i say that we all respect, and indeed admire the fact that, when you were unsure, you asked advice....
Far too many people [who should know better] would just have a guess, sooooooo, well done you!!!!
john...
The problem you have, is that, as Sidewinder has explained, there are PERFECTLY good and valid arguments both for and against bonding. The best thing you can do [in order to protect yourself] is to ask the BCGA for their advice, or ask the makers of the equipment, both courses of action that Sidewinder suggested earlier.
You might find that the "experts" from the BCGA change their minds from time to time too, [as has been done in the case of arrangements for earthing welding sets..]
Best thing is to ask these people and just do what they recommend at present. Once you know what they recommend, then, if they do recommend bonding, you will have the problem of precisely how to go about this, but that is a problem for another day..
Finally, can i just say that no matter what level of experience or knowledge you have of electrical installations, i think i can speak for ALL of us on here, when i say that we all respect, and indeed admire the fact that, when you were unsure, you asked advice....
Far too many people [who should know better] would just have a guess, sooooooo, well done you!!!!
john...
Doc Hudson
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I am just confused as to who is responsible for this work? On one hand it reads as though you are doing it, but then you say you are not a spark. As such it would be best to leave it to those responsible for the work to make the decisions. Hence my comments that every competent electrician should easily be able to identify if metal work is extraneous or not. Once that is established any other relevant points can be considered to make a final judgment.
There is always a tricky area with forums where a question is asked and various members have to decide at what level to write their answers. It is no good someone asking a DIY person what their Ze is or if they have ramp tested the RCD. Just as it can be daft asking a competent person some basic questions. When conflicting views of competence are evident, often members ask other questions to help them narrow down how to do further replies, rather than just going over someones head or assuming that tests have been done that maybe haven't. I still think the first step is to categorically establish if this pipework is or isn't extraneous, with a simple continuity test.
I trust you also understand that it is not uncommon on forums for some posters to enjoy adding deliberate wind-up threads. and stringing topics along infinitum. As the concept of extraneous -vs- non extraneous is relatively easy for any person engaged in electrical work then some of your posts do have some typical conflicting hall marks. You are working but not a spark, you know what is extraneous but have not tested. etc. I am sure you can appreciate the difficulties of getting the right level of answer in an environment where body language cannot be seen. I apologies if you feel slated and hope you will continue to use the forum in the future.
Doc H.
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because it can only be determined on-site by testing. how exactly are we supposed to be able to do that on an internet forum, where most of us are probably hundreds of miles from you?
go do as Special Location said and find someone competent to do the work
gavindrummond
Senior Member
Regardless if the students are not allowed to take the bottles into the building and fit it onto the back of the welder and secure it. This is what they are expected to do once they are working, so they should be taught to do this and taught the dangers involved and take responsibility.
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