Binding Head Screw Terminals

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Jgkopp

Member
Location
San Clemente
I would like it to be mandatory for manufacturers to put information specs in how electrical is to be connected if they choose not to provide box lug connectors.

There is a restriction by the component manufacturer as to wire size that is allowed for a binding head terminal. HVAC Equipment manufacturer instructions have one reference the NEC for electrical connections. The photo I attached showing #8 THHN wire is not approved by the component manufacturer.

http://imageshack.com/a/img924/8837/sLLcUF.jpg
 
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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
The question is why is a #8 being used on those terminals. Is that the required size or is someone oversizing the circuit? The manufacturer needs to have a terminal sized for the wires needed for their unit. If it is not then letters and phone calls need to be made to the mfgr.
 

Jgkopp

Member
Location
San Clemente
This same component is used by manufacturer [Lennox Ind. & their subsidiaries] on residential HVAC Equipment 1 - 5 ton. Other manufacturers provide box lug on field hook up side of contactors. I have been harping on this subject with said manufacturer for years with no results. Looks like I have finally found a place to post my story. There are 100's of thousands of units not correctly connected.

John
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Its not, and I agree it should be required when larger conductors may be in use.
the thing is that the terminal is labeled in some way with the largest size wire that is allowed. I don't know what more you expect of the manufacturer.

why do you want to use a larger wire than the terminal is rated for?

what if the terminal is only rated for #10 and someone decides to use 1/0? if that were to happen it is the installers responsibility to figure out how to do it. it is not real hard to splice a #10 conductor to the end of the 1/0 conductor so the #10 can than be connected to the terminal.
 

Jgkopp

Member
Location
San Clemente
the thing is that the terminal is labeled in some way with the largest size wire that is allowed. I don't know what more you expect of the manufacturer.

why do you want to use a larger wire than the terminal is rated for?

what if the terminal is only rated for #10 and someone decides to use 1/0? if that were to happen it is the installers responsibility to figure out how to do it. it is not real hard to splice a #10 conductor to the end of the 1/0 conductor so the #10 can than be connected to the terminal.
The componet is not labeled with this information. I had to do a lot of digging to get this information.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Let me ask you this- you mention 1-5 ton range. I would think that 1-2 ton would be wired with 12-10ga conductors. But if you are saying that the requirements for the larger units require a wire size larger than the #10 the clamp plate can accommodate, then yes I agree that the manufacturer needs to make some changes.

-Hal
 

Jgkopp

Member
Location
San Clemente
MCA for a Lennox 5 ton unit is 29.6 amps with a MOC of 50 amps. Following NEC Article 440 this unit could operate on #10 wire with a 50 amp breaker however, proper wire sizing guidelines for distance and temperature could more than likely dictate a larger wire size. We typically find #8 wire for 4 & 5 ton condenser unit installations.

A 4 ton unit is 24.2 & 40 respectively.

At a minimum I think installation instructions need to address this with verbiage.

Interesting thread on our HVAC Talk site. Time Builder introduced this site within this thread. He speaks highly of this organization.

http://hvac-talk.com/vbb/showthread.php?2178431-confusion-Some-contractors-on-here-have-sizing-wire-and-breakers-on-ac-units/page14
 

tom baker

First Chief Moderator
Staff member
Since you posted this in the Proposal topic, we need to see some suggested language and what code section it would be in. Then we can comment.
While this is more of a UL issue, perhaps a well worded proposal would get more attention from UL, et al
 

Jgkopp

Member
Location
San Clemente
Since you posted this in the Proposal topic, we need to see some suggested language and what code section it would be in. Then we can comment.
While this is more of a UL issue, perhaps a well worded proposal would get more attention from UL, et al
Thanks for your clarity, yes this could be a UL issue. I think they [UL] could require that the part have verbiage of this limitation on the label. This still does not address how the installer handles connecting a larger size conductor than what's specified by the component manufacturer.

If the code book were to address this, it could read "Binding Head Screw Terminals - The manufacturer shall state the maximum size conductor allowed with this connector. If connecting a larger size conductor, it shall be required to utilize a mechanical connector approved for this size conductor".

This being such a common occurrence, it needs to be stated by code that it is ok to hook up a larger conductor than the "max" specified by the component manufacturer.

john
 

kwired

Electron manager
Location
NE Nebraska
Most terminals with the pressure plate like you showed that I have seen are usually rated to accept 8 AWG.

I can't recall ever seeing a 5 ton unit that needed larger then 8 AWG, unless it had electric heating in it, but then you typically are not landing directly on a contactor either in those instances.

You usually need a disconnecting means near the unit, if voltage drop is an issue run the larger conductor to the disconnecting means and a smaller conductor the short distance of the disconnect to the unit.
 

Jgkopp

Member
Location
San Clemente
Most terminals with the pressure plate like you showed that I have seen are usually rated to accept 8 AWG.

I can't recall ever seeing a 5 ton unit that needed larger then 8 AWG, unless it had electric heating in it, but then you typically are not landing directly on a contactor either in those instances.

You usually need a disconnecting means near the unit, if voltage drop is an issue run the larger conductor to the disconnecting means and a smaller conductor the short distance of the disconnect to the unit.
Thanks for your input. How did you know most are approved for #8? I looked up this component manufacturer product catalog surprised to read that #10 was max. No mention of stranded or solid so you have to assume they approved for both. Other than this one location for this data it is non existent.
 

kwired

Electron manager
Location
NE Nebraska
Thanks for your input. How did you know most are approved for #8? I looked up this component manufacturer product catalog surprised to read that #10 was max. No mention of stranded or solid so you have to assume they approved for both. Other than this one location for this data it is non existent.
I don't know, but seems like most that I can recall would accept #8.
 

Jgkopp

Member
Location
San Clemente
Your where I was at till I looked into this further and was surprised to learn about this #10 limitation. Number 8 fits too, but that makes this a connection that is not UL listed. This exposes a contractor to unintended additional liability. Then one has to wonder and question why the component manufacturer published this wire size as the limitation? They must have their reasons. Then I add a UL listed connector approved for the size wire I am connecting but technically this limitation is still in play.

i could see this being addressed by UL. But if they don't, there has to be an approved way of connecting larger wire sizes to Binding Head Screw terminals.
 
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