Safety Issue?

[pepinbox]

I am interested in any comments this community has on the following scenario:

The Contractor was unable to complete the installation. The existing 800AF/800AT main breaker will accommodate three 400 MCM conductors per phase but not the three 500 MCM conductors per phase as specified.

The Contractor was directed to use compression type pins to adapt the 500 MCM feeders to a size acceptable by the new triple lugs.

Before crimping the new compression pin to the conductor the Contractor assessed the final installation by inserting the pins in the lugs in the proper orientation. The diameter of the compression barrel forced the Contractor to orient the adapter such the pin embedment in the lug was not sufficient to tighten the hold-down screw. The lugs are physically too small to accommodate three 500 MCM conductors.

Therefore the Contractor replaced the original dual 500 MCM lugs on the existing main breaker and terminated only 2 of the 3 500 MCM per phase conductors. The third 500 MCM conductor was made safe at each end and secured to the back of each panel.

Since the main breaker is rated for 800 amps and dual 500 MCM conductors are rated for 760 amps (assuming 75-degree Celsius conductors were used) the interim installation is acceptable.

end

 

[thinfool]

Re: Safety Issue?

Originally posted by pepinbox:


The Contractor was directed

So the Contractor was "doing what he was told". If he followed plans and specs and then ran into trouble, the solution rests in the hands of the engineer. If the engineer ultimately had the contractor abandon the third set of feeders, it should reflect on his design experience, or lack thereof.
Some would critique the contractor, but in this scenario, he wasn't being paid for design engineering, just for installing what had been designed by someone else.

 

[royal]

Re: Safety Issue?

Pepinbox:
What type of distance are we talking here that initially required the design calling for 3 500MCM/phase feed? What kind of voltage are we talking?

Tim

 

[iwire]

Re: Safety Issue?

Here is what I see.

Three 500s provide an ampacity of 1140 amps. (assuming they are run in separate raceways)

The breaker in question is an 800 amp.

This suggests to me that 500s where chosen either to overcome voltage drop or high ambient temperatures.

If the above is true I would simply splice a few feet of 300 to 400 kcmil using compression splicer reducers on to the 500 kcmil then land these smaller conductors on the breaker.

[ November 19, 2005, 06:20 AM: Message edited by: iwire ]

 

[infinity]

Re: Safety Issue?

Something about your post didn't sound right so I checked some pin adapters. Your electrician didn't have the correct pin adapter. Take a look at this link. They come in all different pin sizes:

https://portal.fciconnect.com/portal/page?_pageid=335,1577141&_dad=portal&_schema=PORTAL&language=EN&ctx_titles_list=%7CProduct%20type%3A%7C%7C%7C&ctx_labels_list=%7C%7CCompression %7CMedium%20and%20Large%20Terminals%7CCopper%20Pin%20Terminals&ctx_images_list=connection.jpg%7Cconnection_electrical.jpg%7Csaqqara%2F030.jpg%7Csaqqara%2F047.jpg%7C&ctx_pages_list= %7CPAGE_CT_ELECTRICAL%7CPRODUCT_TYPE%7CPRODUCT_TYPE%7CSTEP_SEARCH&ctx_urlparams_list=%7Cnop%7CcategoryNodeName%3DCOMPRESSION_CONNECTORS%7CcategoryNodeName%3DTERMINALS%7CfamilyName% 3DYEP&cur_label=563&productID=YE34P63X126&P=132650,115195,135449&FAM=563

 

[iwire]

Re: Safety Issue?

Trevor I believe the problem is not the pin but the outside diameter of the crimped area.

 

[infinity]

Re: Safety Issue?

Bob,

I re-read the original post and you may be correct. Burndy does however make offset pin adapters for that purpose too.

 

[charlie b]

Re: Safety Issue?

Since you posted this in the "Safety" topic area, I'll address the one safety issue that I see. The others can address the "what do I do now" issues.

It does not matter that the breaker is rated for 800 amps and the conductors are rated for 760 amps. That is acceptable by itself. What matters is the calculated load. If the calculated load is at or below 760, then this installation is safe. If the calculated load is between 760 and 800 amps, then this installation is not safe. You need to have conductors rated at or above the calculated load.

 

[pepinbox]

Re: Safety Issue?

Thanks for all the feedback.

Thinfool - I agree, the contractor is not to blame.
Actually, we are not assigning any blame, we just want to ensure a safe install.

Royal - The parameters you requested are 480VAC and 340Ft.

iwire - Yes, we are considering running smaller cable out or a terminal block, but at present have not found a great location for it.

infinity - Thanks for the link.

Charlie-b - That's exactly the question that we are trying to get answered from the design engineer - What is the calculated load?!

Thanks again to all.