Made a service call. Connect up a large screen TV. Extended the cable (coax) to the sets location. Hooked the cable to the cable box. Pluged in both the TV (3wire cord) and the cable box (2wire cord) I then connected the RCA video & audio cables to the back of the cable box and my helper plugged the rca cables in to the monitor and spark and smoke came out of the cable box. The RCA cable melted. I quickly pulled the plugs. I connected the TV an measured 120v between the cable box (shield) and the TV chassis. Both cable box and TV were plug into a Isolated Ground receptacle. The building was a bank and is now a coffee house. I checked the outlet and found 120v between the ground prong (hole) and the cable shield, and between the ground prong (hole) and the box. I found the breaker controlling the ckt. and turned it off. All voltages gone. Removed the outlet, found it was served by 12/3 bx with BK/WH/RD with the RD connected to the IG ground terminal. Someone had connected this red wire to the hot line in the J box in the ceiling. I removed the hot and installed a propery wired receptacle. The band members has been using this receptacle for their equipment and complained about hum. The fact that all their equipment was electricly hot, it is a wonder someone did not get electrocuted. Always use caution with IG receptacles. Robert

Unfortunatly. having worked as a commercial sound technician for many years, the FIRST thing many people do when there system hums is yank the grounding pin. Audio signals (TRS & XLR connectors) are usually tied in with the electrical ground of the sound system. This creates a loop, which can cause a hum. The proper way to get rid of a hum is to transformer isolate the audio line, or ground lift the audio line itself. Leave the electrical connection alone. Sorry. This has always been a rant of mine.

As for the outlet in the bank/shop, isolated ground outlets are nice when wired right. Whoever used a red wire as hot should be shot. People like me get sent to the hospital because of stunts like that.

-Ben

Red is supposed to be hot. Ground wires are bare, green, or green with one or more yellow stripes.

HCF cable is designed to do what they were trying to do there.

[This message has been edited by SolarPowered (edited 11-21-2006).]

It seems to be the way here in Ontario Canada as well to use the red of a 3-wire bx for the ground on a dedicated ground outlet.

I usually candycane tape the red with green tape to let others know of its intention.

So far this is a non issue with our local authority.

I know we talked about reidentifying the red as a ground before. As far as I know there is no problem with that as long as it's reidentified at BOTH ENDS. This was not the case here and apparently someone came along and assumed the red was a hot.

They do make IG MC cable, it has two grounds- one green and the other (IG)yellow/green. You don't need to go as far as HCFC cable.

-Hal

[This message has been edited by hbiss (edited 11-22-2006).]

Smokeumchevy:
Ya I have seen the red as an IG many times before as well, BUT now if thats the case the inspector will not even pass it if its taped green, you MUST re-identify the red with GREEN heat shrink tubing.

BTW where in Ontario are you? Just wondering as I am in "The Hammer".

A.D

smokumchevy...... check 4-036. Red has not been permitted in the Ontario code for at least the last few years now ever since they started manufacturing the BX cable with the green coloured conductor.

edit : to insert code number




[This message has been edited by Sandro (edited 11-22-2006).]

In Victoria we used to allow the red wire in BX to be taped green for IG outlets. Since ISO bx has become redily available we will no longer permit green tape on a red wire. Red is not a good color for a bonding conductor and this illustrates the reason.

Quote: "This was not the case here and apparently someone came along and assumed the red was a hot."


Exactly why we can not just tape it a different colour anymore. And the fact that the right colours are available.

I am also in Ontario GO SENS GO !

Another question that comes to mind is where did the original installer intend to land that IG in the box? It's supposed to go back to the service ground bar. Ground it to the box and you don't have an IG and you are wasting your time with an IG receptacle.

That is if you aren't wasting yout time with an IG anyway...

-Hal

At our shop we have a box of orange ID receptacles that we've collected from commercial fit-ups. Must be a few hundred in there! Wonder if we'll ever need them again?

No, I understand the code, what I was stating was that taping is still slipped by with the local inspectors here. And I meant IG not dedicated grnd.

The 4-wire (insulated grnd, bare grnd, white, red, black) bx IS however insisted on for patient care.

In the banks we do around here, the spec always require IG plugs even on a system with no isolated grnd bar in the panel. When asked if the want a true IG system, they say no.

I'll usually intall an IG bar in the panel if doing the service install with a ground to the same beam as the building ground if time and $$ allows.

Westuplace, I'm sorry, we seem to have deverted your thread and I appologize.

Rewired: I'm in Ottawa.

Eddy: I gave up on hockey when they started making it a womens sport (no fighting), too boring and too long watching players constantly going to the box.

-Greg

GOSH THATS Embarrassing!!!! I should not be typing late at night. I meant to say, whoever used red as a GROUND wire (without re-identifying) should be shot. Even though it may not be allowed, its less worse than just hoping people figure out that the red wire is actually a ground connection. I've known these color codes sence before I could walk. Slip of my mind, I guess. Sorry for confusion. I once worked on a PA system where the in house maint. department installed the IG outlets. They landed all the grounds on the neutral bar (no ground bar anywhere near the panel, and no bonding) and wondered why I was mad. It all got redone when the place failed an inspection. Some people think that anything that doesn't hurt when you touch it is the same thing. One of the in-house guys said to me "we don't need grounds and neutrals, they both go to the same place". Not the case.

Also, I used to play hockey when I was younger. I used to drive my coach crazy because some of the rink owners would ask me to fix scoreboard problems and such, which would *occasionally* interrupt practices. I can practically wire RG-58 connectors in my sleep.

-Ben

[This message has been edited by napervillesoundtech (edited 11-27-2006).]