Grounding LED's retrofit

[David Rogers]

I have a lighting sales rep that is providing new LED to replace existing fluorescents in a building that was constructed in 1949. There isn't any grounding for the (e) fixtures, and he says that the new, retrofit, LED's will fail much sooner if they are not properly grounded. I understand the purpose of the grounding system, and it is not an operational part of the circuit, but a safety measure. I realize code requires grounding. So this is a double edge sword. Costs related to safety, and possible degradation of new equipment supplied. This is being done for a non profit club, and I'm concerned about costs for the club. What is the legal, safe, and reasonable solution?

 

[retirede]

What’s the current wiring method?

 

[Little Bill]

Grounding/bonding in old fluorescent lights had two functions. One was the normal safety reason of bonding, the other was the EGC had to be landed near the socket end to allow the exciter strip in the fluorescent tube to "ignite" better and light the lamp.
I don't know what role the EGC, other than safety, would be on LED lighting. Perhaps the rep is thinking they are needed because of the way fluorescent lights needed them.
Just a thought!

 

[David Rogers]

What’s the current wiring method?

I'm not sure. I have not seen the site. It could be knob and tube or graphite romex, with no ground. The rep, that I know a little, has a tendency to be overly cautious, which is good, But his reasoning seems to be if the ground is missing, the LED fixtures life will be reduced. That does not make sense to me. Also, if the fixtures are ceiling mounted well out of reach of the common user, I was thinking grounding could be excluded in this instance.

 

[David Rogers]

Grounding/bonding in old fluorescent lights had two functions. One was the normal safety reason of bonding, the other was the EGC had to be landed near the socket end to allow the exciter strip in the fluorescent tube to "ignite" better and light the lamp.
I don't know what role the EGC, other than safety, would be on LED lighting. Perhaps the rep is thinking they are needed because of the way fluorescent lights needed them.
Just a thought!

Thanks for that thought, and maybe that is what he is thinking. But this building being built in 1949, could be knob and tube. No ground has ever been there if that is the case. I will be visiting the site tomorrow, so I'll know more then. Thanks again.

 

[tom baker]

Interesting. If the LED luminaire has a EGC, can it be legally installed? In WA our code allows if fed from GFCI

 

[David Rogers]

I know we can retro older installation for receptacles using GFCI. That may be a solution. The only issue that bothers me is that the lighting rep insists fixture failure without EGC.

 

[LarryFine]

If you're replacing fixtures, running an EGC may be a consideration for fixture listing reasons.

If you're just removing ballasts and installing new tubes, grounding should not be an operational issue.

 

[AC\DC]

Why would the fixture fail earlier from lack of egc???
i See no reason why it would cause a problem. Call the manufacturer and talk to one of there engineer. They would give a better answer than a salesman

 

[paulengr]

I have a lighting sales rep that is providing new LED to replace existing fluorescents in a building that was constructed in 1949. There isn't any grounding for the (e) fixtures, and he says that the new, retrofit, LED's will fail much sooner if they are not properly grounded. I understand the purpose of the grounding system, and it is not an operational part of the circuit, but a safety measure. I realize code requires grounding. So this is a double edge sword. Costs related to safety, and possible degradation of new equipment supplied. This is being done for a non profit club, and I'm concerned about costs for the club. What is the legal, safe, and reasonable solution?

One of the problems with the word “grounding” is that we use it for EVERYTHING not part of the main power path. He is referring to system grounding. You are referring to bonding (mostly).

Bonding means every metal part is connected together to keep the voltage near zero to prevent shocks. In grounded systems it also provides current feedback to allow breakers to trip.

System grounding has to do with the overall system. In an ungrounded system typically the secondary side of the transformer is delta (wye can be used too). Unlike low voltage the transformer is not intentionally grounded. All phase conductors form a capacitor with the bonded (grounded) metal parts. During faults with an arcing fault the line interacts with this capacitance and you get huge voltages, often 6-8 times the line voltage. These huge transients destroy power electronics and motors. Sounds like the sales rep has had experience with one of these systems.

Today Code requires grounded transformers for anything under 250 V. Above that Voltage grounding is optional by Code but I’d say 95%+ of plants run grounded systems. It is rare enough that most electricians have never seen it. Insurance companies frown on it. The big advantage is that as long as it’s not arcing, the first ground fault is “free”. The plant continues runnjng as a corner grounded delta so it can be safely shut down and repairs made. That’s the second issue…plants are unwilling to shut down to find it, and ground faults on ungrounded systems can be very difficult to track down.

As a result your sales rep was probably told that all warranties on ungrounded systems are void.

There is a third option, high resistance grounding, that is superior.