ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Unusual Well Pump Switch Failure
by sabrown - 10/28/20 04:31 PM
Look at this mess...
by InspectorE - 10/27/20 09:09 PM
New tool
by gfretwell - 10/24/20 11:09 AM
Where is Everyone?
by Bill Addiss - 10/17/20 07:04 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 14 guests, and 17 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
50 amp breaker on 1/0 conductors #41465 08/28/04 09:48 AM
Joined: Dec 2003
Posts: 11
M
Macon Circuits Offline OP
Member
I work in the maintenance department of a mail processing plant. The plant operates numerous hi-tech sorting machines utilizing computer and electronic technology that boggles the mind.

The manufacturer of a particular piece of equipment has sent out a national maintenance order requiring that all of these machines nationwide be protected by a 50 amp breaker. So I have been instructed to swap out the current 80 amp breaker with a 50 amp breaker which was shipped to us from our national maintenance technical center. This special breaker is simply a Square D, QO, 50 amp 3 phase HACR rated breaker wich fits our particular panel.

The problem is that the original specifications for this machine required that 1/0 conductors be pulled for the equipment power with a full sized neutral and ground. The 50 amp breaker will not accommodate the 1/0 conductors. The engineers at the national maintenance center have instructed us to install a junction box at the panel and splice the 1/0 conductors with #2awg conductors using split bolt connectors, then connect the 50 amp breaker to the #2 conductors.

The machine is also protected by fuses and breakers at its disconnect panel.

This makes no sense to me. My questions are how does this affect voltage drop? And is there another better way to provide 50 amp over-current protection to 1/0 conductors?

My personal opinion is that the 80 amp breaker is adequate to protect the conductors and the machine, especially given the OCP devices on the equipment. What do you all say?

Sorry this is so long!

Work Gear for Electricians and the Trades
Re: 50 amp breaker on 1/0 conductors #41466 08/28/04 09:56 AM
Joined: May 2002
Posts: 1,716
R
Roger Offline
Member
I tend to agree with you. If the machine has it's own protection, the upstream protection could be anything.

As far as Voltage Drop the larger (1/0) conductors are a plus.

The J box and splice sounds like the best way to accomplish this so that is not a problem.

Now, even though you and I agree, it doesn't hold much weight, the manufacturer has found this neccessry for some valid reason and to maintain warranty and or safety (more important) they say you must do it.

Roger

Re: 50 amp breaker on 1/0 conductors #41467 08/28/04 10:16 AM
Joined: Jun 2004
Posts: 613
S
shortcircuit Offline
Member
One of the magazines I have has an ad for "ReduceR" connectors that are for your application. Cable reducing adaptor plugs...used to terminate copper conductors where oversized cable is used to compensate for voltage drop.For sizes 1/0 to 1000mcm

Re: 50 amp breaker on 1/0 conductors #41468 08/28/04 11:21 AM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
 
Suggested components may be:

www.fciconnect.com/pdffiles/brochures/Section_C_2003MC-Compression.pdf

TYPE YE-P “HYPLUG” FOR COPPER CONDUCTOR page 115 are likely not suitable for QO-breaker terminals.

TYPE YH H-TAP COPPER “CRIMPIT” page 107 with ~4AWG-stranded cable “pigtail”/jumper may permit a compact reducing splice.

Hydraulic tooling required for either.

N.B., physically larger “industrial E/F-frame” 15-150 ampere molded-case circuit breakers are routinely available with terminals for 1/0AWG conductors.




[This message has been edited by Bjarney (edited 08-28-2004).]


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Samurai
Samurai
Fl.
Posts: 46
Joined: May 2007
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
271,051 Are you busy
205,040 Re: Forum
193,164 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3