I have an older home with a mix between romex and pbx wiring. I was testing the outlets and found that there are 2 that are not grounded, which are fed with pbx. I found the junction box in the light fixture that they are connected to was replaced w/ a blue plastic box and there is nothing that grounds the 4 pbx wires going into it together (source feed, switch & 2 outlets)
My question is, should I attempt to solder a common ground wire between each pbx wire, or replace the junction box? I'd rather not replace the box, but I will if there are no other alternatives. Are those plastic boxes made to support pbx wiring?
Connections that depend on solder are not permitted in the Equipment Grounding Conductor.
250.8 Connection of Grounding and Bonding Equipment. Grounding conductors and bonding jumpers shall be connected by exothermic welding, listed pressure connectors, listed clamps, or other listed means. Connection devices or fittings that depend solely on solder shall not be used. Sheet metal screws shall not be used to connect grounding conductors to enclosures. Copyright 2002 National Fire Protection Association.
If there is room in the box and the connectors that attach the cable to the box are of the external type with threads that protrude into the box and are held with a lock nut then you can apply half inch bonding bushings or wedges to each connectors threads and run a bonding conductor between the four connectors to reestablish the Equipment Grounding Conductor's continuity.
314.3 Nonmetallic Boxes. Nonmetallic boxes shall be permitted only with open wiring on insulators, concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways. Exception No. 1: Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables. Copyright 2002 National Fire Protection Association.
I hate those plastic boxes. Mostly because there is no way to ground them. On the metal boxes there is a hole on the rear for a green screw. They never put the holes on these plastic boxes, so I am stuck with ungrounded boxes, I do not like that at all.
Electrical boxes have been grounded ever since safe grounding methods went into use. Just when we finally had very safe electrical systems, if the codes are followed, we are now going backwards. The purpose of grounding electrical boxes is to protect the user from electricution. Now, with these ungrounded plastic boxes, the user is once again in danger of electricution from touching the box. Granted, the ground terminal (green screw) on the outlet is connected to ground, but not the box itself. I personally refuse to use these plastic boxes. Not only are they dangerous to people, but are also a fire hazzard, since they burn if an outlet fire starts, and actually add to the fire.. A metal box provides some means to stop a fire before the fire gets to flammable materials, and surely does not ADD to the fire.
I understand your choice in metal boxes over plastic is based on your experience and option; so, nothing wrong there, but I too was skittish about plastic boxes till I found they are rated for 2 hours, which gives time for your evacuation, and extinghishing of it.
It's REALLY hard to electrocute yourself by touching a plastic box. Not quite impossible, but tough. I'd say that a grounded metal box is probably more dangerous, as it provides electricity from other sources with someplace to go.
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