Double lugs in panel to tap conductors.
- Thread starter darekelec
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Certainly... but I add as a reminder that not just feeder tap rules apply. Details can make or break what otherwise seems to be a compliant installation on the surface.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
Also, if the new conductor size is the same as the incoming conductor size, it is not a tap.
Unless the original conductors themselves are not properly protected by upstream OCPD, in which case it might be a service tap that you are doing, with different rules.
If the panel is "adjacent", then why not just use appropriate sized conductors (if it actually is a feeder tap).
I would contact the panel manufacturer first regarding the modification of their panel. If the panel could have been ordered with "sub feed lugs" it would be appropreate to so ply order those lugs. .If not, ask if you can abb a set of sub feed lugs which are commonly onstalled at the opposite end from the main lugs.
But there are those who avoid asking the manufacturer because they want to avoid getting an answer that they don't want to hear and instead ask around. There must be enough wire bending space for the additional cable.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Again, industry slang rears its ugly head.
For at least one manufacturer:
Sub feed lugs are installed at the same end as 'main lugs only' or before a main breaker. Panel height is hardly affected, panelboard main does not see current from downstream loads.
Through feed lugs are usually installed at the opposite end of the bus assembly from the main lugs or anywhere after the main breaker. Panel height is larger, current from downstream loads flows through the main.
kwired
Electron manager
- Location
- NE Nebraska
And other than a few select models, you are usually looking at the "commercial" panelboards that will have subfeed or feedthru lugs and not the typical off the shelf "loadcenter"
petersonra
Senior Member
- Location
- Northern illinois
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- engineer
It may or may not be legal. if the conductors coming in are tap conductors you cannot "tap" them.
The double lug idea is fine, presuming it is done correctly.
You did a very good job of interpreting my terrible post Jim which I find to be most amazing. Thank you.
That is exactly what I was trying to say. My concern was that any modification that are being made are within the panels UL listing.
With through feed lugs being feed by the panels bus attention must be paid to the bus ampacity where subfeed ate not dependent on the bus.
Dave
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Unless you are using the manufacturer's parts kit, field modifications are between you and your AHJ.
According to UL's White Book.
"What happens to the Listing if a UL-Listed product is modified in the field?
An authorized use of the UL Mark is the manufacturer?s declaration that the product was originally manufactured in accordance with the applicable requirements when it was shipped from the factory. When a UL-Listed product is modified after it leaves the factory, UL has no way to determine if the product continues to comply with the safety requirements used to certify the product without investigating the modified product. UL can neither indicate that such modifications ??void?? the UL Mark, nor that the product continues to meet UL?s safety requirements, unless the field modifications have been specifically investigated by UL. It is the responsibility of the Authority Having Jurisdiction (AHJ) to determine the acceptability of the modification or if the modifications are significant enough to require one of UL?s Field Engineering Services staff members to evaluate the modified product. UL can assist the AHJ in making this determination.
An exception for a field modification authorized by UL is when the product has specific replacement markings..."
kwired
Electron manager
- Location
- NE Nebraska
Yet we have so many discussions here about violations of listings. IMO the listing only applies to equipment as it comes from the manufacturer. Once installed and put to use those conditions begin to deteriorate, even if very slightly. Then you have field installed items that are changes whether they comply with the listing or not. Simply drilling a mounting hole means it is no longer in the same condition it was in when it left the manufacturer. Might not seem like a big deal, but it depends on the application - drilling a mounting hole in hazardous location equipment can be a big deal.
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