# Point to point testing



## glen1971 (Oct 10, 2012)

Are you talking about the pre-installation cable checks that are in some specs? The only way we've done them is one at a time to each other conductor and of course each one to ground.. 
Or is someone asking you to do point to points from a PLC/cabinet to a junction box, then from the junction box to the end devices? This, in my opinion, is the biggest waste of time when doing point to points..


----------



## 2000kwem (6 mo ago)

Need someone person, or company to do reverse point-to-point drawing on our 15Kv control and wiring. We are located in Mississippi. Does any on have any information or contact to help us Out. Ed Csapo 805 689 6776


----------



## just the cowboy (Sep 4, 2013)

2000kwem said:


> Need someone person, or company to do reverse point-to-point drawing on our 15Kv control and wiring. We are located in Mississippi. Does any on have any information or contact to help us Out. Ed Csapo 805 689 6776


Best to start a new thread, this one is dead.


----------



## joe-nwt (Mar 28, 2019)

I'll take the opportunity to agree with this statement though.  



glen1971 said:


> This, in my opinion, is the biggest waste of time when doing point to points..


Since I wasn't here when he made it......


----------



## mburtis (Sep 1, 2018)

I've never worked in the electrical construction field, just maintenance. Can some one explain this point to point testing or commissioning? Do you literally pull in all your wires and terminate them, just to turn around and unterminate them to ring them out to make sure one didn't get damaged in the pull? Then reterminate them. I would be more worried about damaging the wire ends or the terminations or landing on the wrong terminal. Seems like a complete waste of time thought up by some egg head who doesn't trust electricians to pull wire properly.


----------



## Bluenose for rent (Nov 6, 2020)

mburtis said:


> I've never worked in the electrical construction field, just maintenance. Can some one explain this point to point testing or commissioning? Do you literally pull in all your wires and terminate them, just to turn around and unterminate them to ring them out to make sure one didn't get damaged in the pull? Then reterminate them. I would be more worried about damaging the wire ends or the terminations or landing on the wrong terminal. Seems like a complete waste of time thought up by some egg head who doesn't trust electricians to pull wire properly.


I mean if you want to energize something that parallels thirty conductors without megger testing it I guess go ahead… we megger stuff like that before we terminate them though. Or maybe he’s talking about falll of potential on the terminations?


----------



## joe-nwt (Mar 28, 2019)

mburtis said:


> Seems like a complete waste of time thought up by some egg head who doesn't trust electricians to pull wire properly.


Close. Thought up by some egghead that can see wires on paper but not in the field.


----------



## gpop (May 14, 2018)

mburtis said:


> I've never worked in the electrical construction field, just maintenance. Can some one explain this point to point testing or commissioning? Do you literally pull in all your wires and terminate them, just to turn around and unterminate them to ring them out to make sure one didn't get damaged in the pull? Then reterminate them. I would be more worried about damaging the wire ends or the terminations or landing on the wrong terminal. Seems like a complete waste of time thought up by some egg head who doesn't trust electricians to pull wire properly.



That kind of work is for a ring out crew. 
Honestly most of the land out is done by people who have no understanding of what they are doing its simply this wire to this terminal. The ring out crew have a better understanding and its basically double checking and quality control. 
I did one last year and had a list of over 80 problems before dinner. They asked me to stop so the land out crew could go back in. Over 40 of these where due to the engineer drawing the terminals on a din rail mounted surge suppressor incorrectly.

What sucks is over the past year i have found 3 errors that i missed.


----------



## glen1971 (Oct 10, 2012)

mburtis said:


> I've never worked in the electrical construction field, just maintenance. Can some one explain this point to point testing or commissioning? Do you literally pull in all your wires and terminate them, just to turn around and unterminate them to ring them out to make sure one didn't get damaged in the pull? Then reterminate them. I would be more worried about damaging the wire ends or the terminations or landing on the wrong terminal. Seems like a complete waste of time thought up by some egg head who doesn't trust electricians to pull wire properly.


Back to the OPs original topic from a decade ago, when I do a point to point on a job it is to isolate a wire at the PLC, MCC, DCS or whatever the source is, and verify it to the field device, using an ohmmeter. Usually both ends are isolated to verify it to be right, so fuse pulled, knife pulled, transmitter disconnected, NO contact. And it's all documented.


----------



## paulengr (Oct 8, 2017)

gpop said:


> That kind of work is for a ring out crew.
> Honestly most of the land out is done by people who have no understanding of what they are doing its simply this wire to this terminal. The ring out crew have a better understanding and its basically double checking and quality control.
> I did one last year and had a list of over 80 problems before dinner. They asked me to stop so the land out crew could go back in. Over 40 of these where due to the engineer drawing the terminals on a din rail mounted surge suppressor incorrectly.
> 
> What sucks is over the past year i have found 3 errors that i missed.


This is rarely done. It’s such a basic test unless you pull the cable apart o it won’t show anything. The only time we use it is if we unsure if the labels.

Sometimes on critical connections some old school engineers still bother hi potting cables. This has sometimes been replaced with partial discharge owing to the fact that hi pit never finds anything if you Megger first per procedure:. In Europe they do loop testing but that’s very different. But this is more about testing workmanship of the terminations which you can’t check any other way.

Usually in power distribution this is part of commissioning. You are checking voltage and verifying everything along the way. In IO checkout for controls typically you go line by line through each device testing basic functions like does an auxiliary input turn on if you force the contactor in. It’s not so much full calibration testing so usually you might just check if an RTD reads room temperature and the signal goes to open if you lift the wire. Between these two tests by the time you get to startup over 90% of installation issues are resolved. If you honestly count up how many terminations there are even a small $50k controls job can have hundreds. It is very easy to make mistakes.


----------



## gpop (May 14, 2018)

paulengr said:


> This is rarely done. It’s such a basic test unless you pull the cable apart o it won’t show anything. The only time we use it is if we unsure if the labels.
> 
> Sometimes on critical connections some old school engineers still bother hi potting cables. This has sometimes been replaced with partial discharge owing to the fact that hi pit never finds anything if you Megger first per procedure:. In Europe they do loop testing but that’s very different. But this is more about testing workmanship of the terminations which you can’t check any other way.
> 
> Usually in power distribution this is part of commissioning. You are checking voltage and verifying everything along the way. In IO checkout for controls typically you go line by line through each device testing basic functions like does an auxiliary input turn on if you force the contactor in. It’s not so much full calibration testing so usually you might just check if an RTD reads room temperature and the signal goes to open if you lift the wire. Between these two tests by the time you get to startup over 90% of installation issues are resolved. If you honestly count up how many terminations there are even a small $50k controls job can have hundreds. It is very easy to make mistakes.


I have friends who do this for a living on large industrial jobs. 

They were telling me on one job they found the transformer to the switch gear shorted to ground. Turned out to be a set of ground clamps that had been left on the main switch gear buss in a hard to see area. That simple find may have saved a few hundred for pad mount fuses or many thousands for a damaged mcc. 

If you have one team onsite and they are known for quality work then it might be a waste of money. Im not that lucky so im insisting on a ring out on the next build being included in the bid package.


----------



## joe-nwt (Mar 28, 2019)

gpop said:


> I have friends who do this for a living on large industrial jobs.
> 
> They were telling me on one job they found the transformer to the switch gear shorted to ground. Turned out to be a set of ground clamps that had been left on the main switch gear buss in a hard to see area. That simple find may have saved a few hundred for pad mount fuses or many thousands for a damaged mcc.
> 
> If you have one team onsite and they are known for quality work then it might be a waste of money. Im not that lucky so im insisting on a ring out on the next build being included in the bid package.


Around here, the installation of grounds is part of the LOTO switching procedure, and thus documented.


----------

