Busbar Short Time Withstand Current

You might try a rationale that you furnished larger busbar to contemplate future expansion, and show him samples of the two sizes.

At a deeper level, I don't really know how to handle complete fools. My sympathies.

I don't see what the objection could be as the part exceeds recommended capacity....Perhaps he is under the impression that this is related to over current protection and that over sizing is a safety hazard......I would explain that this is related to the wiring and will operate the same as a larger wire size would...but there seems to be an issue of trust here...If you could locate someone with an established trustworthy relationship with your client, that would be willing to collaborate your claims, then some progress might be made....I would offer to change the busbar as well...

There's no accounting for stupidity

Maybe he does not understand that 40kA is LESS than 50kA, and that 1 second is LESS than 3 seconds. If that's the case, he is a complete fool.

But maybe it's just a semantics issue, as in maybe he doesn't understand the notation "k" or even "kA", but is too embarrassed to show his ignorance. Did you try just spelling it out?

"This bus is rated to withstand 50,000 Amps for 3 seconds. Your worst case fault is 40,000 Amps for only 1 second. The bus withstand exceeds your fault level by 125% and duration by 300%. No problem."

It depends on the wording of your contract. If your customer specified a specific collection of parts and you choose a more robust collection of parts then regardless of the improvement you are not providing what the customer ordered. I doubt that this is the scenario but I just wish to be thorough. If your contract says to meet this 40KA for 1 second standard and your installation passes a test at 50KA for 3 seconds then a retesting at 40KA for 1 second seems like the easy solution. If no testing has been done or contracted, then an outside firm should review the design or perform this test. Remember your word appears to not be considered valid by the customer anymore. Whomever should pay for the cost of this outside firm is an additional business decision outside of the initial contract to be decided between you and the customer.

If this fails it may be time to release the hounds bring in the lawyers. Consult with your hound if you can refuse the release of the installation until this is settled. This might make your customer more reasonable.

The client is no fool, more than likely he is concerned that the more robust solution is costing him more money, you now have to show him that there is no increase in cost, justify it as others have suggested, or eat the difference.

If what you are saying is true, then why not you change the calculation showing that the busbar can withstand 40kA, 1sec. Why do you need to make any mention of 50kA or 3sec!

Is it not that simple!

After all, client can never be wrong should be our (read vendor / contractor / consultant) motto, isn't it!

No, it is "...not that simple..." in the USA. If the customer orders a review of the design and it is shown to be over-designed at his expense and that fact was withheld from him as you suggest, then OP will be caught in a lie that could cost him his license. Now go explain your ethics to your boss/client/employer!

Dear O/P Where are you located? It may help us understand what seems to be an odd statement. My thoughts are it's price or protection driven. Either way both should be able to be explained. A third party might be a good way to go. Which standard are the boards built to? If you need more assistance let me know Craig

To all the people who have replied to this problem, let me assure you guys that i have tried everything possible to rationalize with the client. He wants a type tested panel with busbar withstanding 40kA for 1Sec. Now we dont have a type test for 40Ka for 1Sec, but we have a type tested certificate for 50Ka for 3sec and 36KA for 1Sec. Since the 36kA is out of question here, i provided him the 50KA certified Panel. The project Cost doesn't allow us to hire a third party to certify for 40KA. And Our client is not willing to pay additionally for that either. So now he is asking me a document where its is written that use of higher rated Busbars is allowed? i am located in Qatar and our client is a reputed oil and gas company .So My boss is screwing with me every now and then, so that we can finish the project. (Commercial Problems). so please help me out.

Which standard have you tested your busbar system to? IEC 60439 or 61439?

If you have tested to IEC 61439 there is a clause in the design verification that will let you carry out calculations to prove your system at lower fault currents, you could try that option, but as you and others have said, it's a poor situation when you are being asked to prove something so obvious. Perhaps you could suggest some education for them on the standard ?

One other route would be to talk to the support manufacturer, they may give you something to help your cause, do you know who the supports are made by?

we still follow IEC 60439. Atleast till the end of 2012

There are type tested assemblies (TTA) and then there are partially type tested assemblies (PTTA). In the latter case, it can be proved by calculations that the bus bars are able to withstand a lesser fault current for a lesser duration. The relevant Standard is IEC 61439. I hope that thye do follow IEC in the Gulf.

electrocalexpert65. Just to clarify for you and others. In IEC61439 the terms TTA & PTTA have been removed. The only option is Design Verification, which requires 12 clauses to be verified to achieve compliance. Short circuit testing remains very similar to IEC 60439 tests.

If you have tested to IEC 61439, you are also required to carry out Routine Verification, this makes the assembly manufacturer prove that the equipment being shipped remains in compliance to what had been Design Verified. The O/P would need to do this and carry out some form of check to "prove" his busbar system is capable of what the customer requires.

I've been in this business for over 20 years now and this is the first time I have ever heard and comments like this and I work with many clients in the middle east. To be honest though I thought Kahramaa required 3 second ratings on most equipment?

EDIT: Sorry, should have said IF you are IEC 61439 compliant, then Table 12 may assist you.