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Old 11-06-2010, 10:12 PM   #1
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Default 500 mcm and dual lugs

Need some input on Connection on a Commercial Hot Water Boiler. The feed is 480v, 500mcm thhn, breaker for the unit is 400 amp and the draw on the boiler is 325 amps. The lugs on the new heater are only big enough to take a wire about half as big as the 500 mcm. I proposed just splitting the wire apart and putting each half into a lug for that phase. I am now hearing that we need to put in 2 conductors for each phase so that one wire will go to each lug.

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Old 11-06-2010, 10:14 PM   #2
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Quote:
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Need some input on Connection on a Commercial Hot Water Boiler. The feed is 480v, 500mcm thhn, breaker for the unit is 400 amp and the draw on the boiler is 325 amps. The lugs on the new heater are only big enough to take a wire about half as big as the 500 mcm. I proposed just splitting the wire apart and putting each half into a lug for that phase. I am now hearing that we need to put in 2 conductors for each phase so that one wire will go to each lug.
2 sets of 2/0 copper would do it and have cost less.

You could call the manufacturer and see if they have or will approve different lugs for the unit.

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Old 11-06-2010, 10:19 PM   #3
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we had planned on using the existing 500 mcm wires

thanks
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Old 11-06-2010, 10:24 PM   #4
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Do not split the wire, that is a poor connection and bad workmanship. Change the lugs on the boiler to the proper size or call an electrician .
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Old 11-06-2010, 11:14 PM   #5
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Old 11-07-2010, 12:26 AM   #6
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I wonder if you could use a Polaris connector. Parallel your conductors from the boiler disco to the tap. I really don't know if that would be legitimate.
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Old 11-07-2010, 01:29 AM   #7
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Quote:
Originally Posted by nitro71
I wonder if you could use a Polaris connector. Parallel your conductors from the boiler disco to the tap. I really don't know if that would be legitimate.
That's exactly what I was thinking. Anyone got any code references for doing that?

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Old 11-07-2010, 01:02 AM   #8
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I proposed just splitting the wire apart and putting each half into a lug for that phase.

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Old 11-07-2010, 01:16 AM   #9
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Mac adapters would probably work
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Old 11-07-2010, 06:22 AM   #10
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Crimp on a sleeve pin of the correct size
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Old 11-07-2010, 06:30 AM   #11
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Quote:
Originally Posted by Bob Badger View Post
You could call the manufacturer and see if they have or will approve different lugs for the unit.
Quote:
Originally Posted by mcclary's electrical View Post
Crimp on a sleeve pin of the correct size
I would do one of these two, I would probably go the pin terminal route though just cause it would mean I wouldn't have to deal with the manufacture.
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Old 11-07-2010, 06:34 AM   #12
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The problem I see is the following

If the manufacturer planed on two sets of say 2/0, 3/0, 4/0 etc. there is a good chance there is not enough wire bending space for 500 Kcmil.

Adding pin terminals will further reduce the bending space and that assumes you could find a pin terminal that would drop the required amount of size and still be rated for 325 amps.

Last edited by Bob Badger; 11-07-2010 at 06:38 AM.
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Old 11-07-2010, 06:37 AM   #13
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Crimp on a sleeve pin of the correct size
Is a sleeve pin, the same as a ferrel?

They are hard to find for 500's.
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Old 11-07-2010, 06:54 AM   #14
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Last 500 mcm pin terminals I priced were like $40 each. And I don't remember there being an amp rating on them but that was a while back and little details like that get lost.
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Old 11-07-2010, 07:11 AM   #15
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Thanks for all the input. It is good to see a lot of valid points and not too much BS. I think we might pull in the new 2/0.. The 500 is already pulled to the unit and bending space is an issue but can be done. I like the idea of the crimp on conn. But gotta get this done today. My lugs unfortunately have 2 holes in the top for the 2/0 and about 16 in the bottom for all my smaller circuits on my heaters and ect. I do follow the logic on not splitting the wire but how much of a difference is it then to put my 2 - 2/0 together on the other end with 2 wires in 1 lug. thanks for all the input.
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Old 11-07-2010, 09:37 AM   #16
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I'd stick to boiler making. Typical of you guys to hack it in.
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Old 11-07-2010, 10:07 AM   #17
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Quote:
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Thanks for all the input. It is good to see a lot of valid points and not too much BS. I think we might pull in the new 2/0.. The 500 is already pulled to the unit and bending space is an issue but can be done. I like the idea of the crimp on conn. But gotta get this done today. My lugs unfortunately have 2 holes in the top for the 2/0 and about 16 in the bottom for all my smaller circuits on my heaters and ect. I do follow the logic on not splitting the wire but how much of a difference is it then to put my 2 - 2/0 together on the other end with 2 wires in 1 lug. thanks for all the input.

2/0 would be too small if you plan on pulling 6 ccc in one pipe.
Distribution blocks are cheep and easy to find.
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Old 11-07-2010, 10:08 AM   #18
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2/0 would be too small if you plan on pulling 6 ccc in one pipe.
That is true.
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Old 11-07-2010, 11:17 AM   #19
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Mac adapters would probably work
I've seldom run across one of them that didn't have an issue, long term.
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Old 12-03-2010, 09:00 AM   #20
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Do not split the wire. The maker of this commercial hot water boiler knows it draws 325 amps, they probably give 2 options dual lugs and single lug. Call them and indicate the 500 MCM already exist and you need thier single lug termination to complete the job to meet the NEC. Throw it back at them.

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