I was looking at a riser that indicated a panelboard(MLO) with double-lugs, and another set of conductors from the second set of lugs feeding another panel. The second panel is approx. 50?-0? away from the panelboard with the double lugs installed, is this considered a ?Tap? and does the tap rule apply, it seems to me since the wire size does not change #4/0 through the circuit that it is not a tap rule as we are not changing conductor sizes. Is this correct or is it considered a tap regardless if you change sizes because the point at which the conductors receive their supply is the double lugs and no OCPD at that point?
Double Lugs??
- Thread starter Mike01
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- Lockport, IL
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- Retired Electrical Engineer
I agree, though I must admit it took me a while to catch on to this tap rule stuff. But if the overcurrent protection is sized such that it protects all conductors downstream, then you are not dealing with a tap.
To take it one step further, it is not a matter of whether you change the conductor size. For example, if you run 4/0 from the distribution board to the first panel, and then run 1/0 for 50 more feet to the second panel, and if the breaker serving this run (at the DP) is 150 amps, you still do not have a tap situation.
To take it one step further, it is not a matter of whether you change the conductor size. For example, if you run 4/0 from the distribution board to the first panel, and then run 1/0 for 50 more feet to the second panel, and if the breaker serving this run (at the DP) is 150 amps, you still do not have a tap situation.
Just wanted to add that transformer conductors are sometimes similar to tap conductors. They can only go a certain distance before overcurrent protection is required.
So if these two panels were fed directly from the secondary of a wye transformer, it would be a problem.
So if these two panels were fed directly from the secondary of a wye transformer, it would be a problem.
Double Lug
Double Lug
Roger, perhaps you can help. Am being scrutinized by the AHJ for installing a sub panel via double lugging a 120/208 main panel being fed by 3 3/0 conductors/1 neut. and current protected via 100 amp breaker downstream located at the main buss.
Per 240.21 I qualify for the 25ft. tap off to my overcurrent CB and then my sub panel to which all conductors and OCCB are installed correctly.
AHJ is stating that the current MAIN panel should not be changed from single lug to double lug due to original build and configuration (i.e. I shouldn't be modifying the panels innards) unless stated as an option on the panel label.
All spacing and lug installation inside meet all requirements with room to boot!, all bolting is mechanically held to torque. Am I msising something?
Thanks.
Mike
Double Lug
Roger, perhaps you can help. Am being scrutinized by the AHJ for installing a sub panel via double lugging a 120/208 main panel being fed by 3 3/0 conductors/1 neut. and current protected via 100 amp breaker downstream located at the main buss.
Per 240.21 I qualify for the 25ft. tap off to my overcurrent CB and then my sub panel to which all conductors and OCCB are installed correctly.
AHJ is stating that the current MAIN panel should not be changed from single lug to double lug due to original build and configuration (i.e. I shouldn't be modifying the panels innards) unless stated as an option on the panel label.
All spacing and lug installation inside meet all requirements with room to boot!, all bolting is mechanically held to torque. Am I msising something?
Thanks.
Mike
I suppose you could use Kup-L-Taps downstream from the lugging and see if he likes that better.
http://ebusiness.ilsco.com/webapp/w...Id=10001&langId=-1&catalogId=1&categoryId=151
http://ebusiness.ilsco.com/webapp/w...Id=10001&langId=-1&catalogId=1&categoryId=151
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