Amp connectors used to join NM cables in manufactured homes ( to join sections together) are allowed to be installed in walls etc. They need no junction boxes. My question is if they need to be accessable, i.e. removable panel or crawl space or can they be plastered over ? In a multi story modular building they are planning on putting them in the ceiling and plastering them over. I think it is a bad design, finding one that fails becomes a major task, but may have to pass it because it isn't a Code violation. Alan--
Every inspector I have talked to about these things say they are only approved for joining modules in manufactured homes. Amp has ping ponged back and forth in the way they market them. They were selling them as a general use item in the 90s, then they pulled back and said they were for manufactured homes. Now I see they are back to saying they can be used in general wiring. I doubt it is a hazard as much as just being a real PITA when they fail. I assume U/L is saying the failure will be contained in the housing. Bear in mind, U/L is not setting a performance standard, only a safety standard. If it blows open and doesn't start a fire it is OK with them. The end user may expect a little higher standard.
They may be safe but, if there is a failure when it is concealed in the ceiling with no access other than ripping everything open I think there is a problem. You can't plaster over a junction box so what makes these things so special ? I have to approve the installation but, some day in the future somebody is going to be blistering my ears about them spending half a day trying to find that open circuit. At least an access plate so someone has a clue about where to look. Alan-- NEC 90.1 Compliance...not necessarily efficient, convienient...etc.
I have spent a lot of time researching these and IMO they are UL listed for use in 'normal' homes and sometimes concealed.
That in no way means I think it is a good idea.
The NEC addressees these in 2002 334.40
334.40 Boxes and Fittings. (B) Devices of Insulating Material. Switch, outlet, and tap devices of insulating material shall be permitted to be used without boxes in exposed cable wiring and for rewiring in existing buildings where the cable is concealed and fished. Openings in such devices shall form a close fit around the outer covering of the cable, and the device shall fully enclose the part of the cable from which any part of the covering has been removed. Where connections to conductors are by binding-screw terminals, there shall be available as many terminals as conductors.
They are also addressed in 550.15(K)
(K) Component Interconnections. Fittings and connectors that are intended to be concealed at the time of assembly shall be listed and identified for the interconnection of building components. Such fittings and connectors shall be equal to the wiring method employed in insulation, temperature rise, and fault-current withstanding and shall be capable of enduring the vibration and shock occurring in mobile home transportation.
550.19 Interconnection of Multiple-Section Mobile or Manufactured Home Units. (A) Wiring Methods. Approved and listed fixed-type wiring methods shall be used to join portions of a circuit that must be electrically joined and are located in adjacent sections after the home is installed on its support foundation. The circuit’s junction shall be accessible for disassembly when the home is prepared for relocation.
As far as approval in the state I live (MA) the AHJ or the inspectors can not refuse to accept UL listed equipment used in compliance with listing and labeling.
Bob Badger Construction & Maintenance Electrician Massachusetts