Igniter on gas stove uses EGC?

[K8MHZ]

I just got a gas stove. It has an electric spark igniter. The spark jumps from an electrode to the grounded frame.

I looked at a diagram for such a device and it shows the N and GND separate, with the spark jumping to the ground.

To me, that means that the igniter wouldn't work if there were no EGC, like in an old house with a two prong receptacle and a three prong adapter.

Is this correct? I am not going to disconnect my EGC to find out, but I am wondering if any of you have run across a gas stove where the igniter wouldn't work because of a lack of an EGC.

The diagram also showed that the spark was 2.3 amps for the spark.

 

[iwire]

No worries, the gas pipe will be bonded.

 

[JFletcher]

Gas stove works fine here with no EGC. Its gonna throw ~50kV DC thru a 1/4" gap from the excited side to 'ground'.

 

[GoldDigger]

There have been reports from members in other threads of spark igniters causing a GFCI to trip, along with second hand reports of igniters that did not operate because there was no functional ground to the appliance (EGC or other).

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[JFletcher]

There have been reports from members in other threads of spark igniters causing a GFCI to trip, along with second hand reports of igniters that did not operate because there was no functional ground to the appliance (EGC or other).

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I'd imagine that many of the latter reports are actually from improper gas/air mixtures. Our stove is touchy like that, sometimes you have to blow air under the diffuser disks to get the thing to light. All 4 burners have sparks timed at ~ 2/second (one igniter unit for all 4 burners). Before I posted I put a cheater adapter on the stove and tested it. Still lit. The gas pipe may be bonded/grounded but all there needs to be is an object (like the metal frame) at a significantly lower potential for that spark to jump. Think of gas grills sitting on rubber/plastic wheels completely isolated from earth/ground reference; the piezo igniters still work (if THEY work). The stove doesnt need a ground reference for the igniter to work; it's its own local ground (lower potential).

 

[GoldDigger]

If the spark generator has one side of its output connected to the metal frame of the furnace, then you are correct that no earth ground is needed.
OTOH if the low side is just connected to the neutral, but the spark is to frame metal then there will be a problem.

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[K8MHZ]

I'd imagine that many of the latter reports are actually from improper gas/air mixtures. Our stove is touchy like that, sometimes you have to blow air under the diffuser disks to get the thing to light. All 4 burners have sparks timed at ~ 2/second (one igniter unit for all 4 burners). Before I posted I put a cheater adapter on the stove and tested it. Still lit. The gas pipe may be bonded/grounded but all there needs to be is an object (like the metal frame) at a significantly lower potential for that spark to jump. Think of gas grills sitting on rubber/plastic wheels completely isolated from earth/ground reference; the piezo igniters still work (if THEY work). The stove doesnt need a ground reference for the igniter to work; it's its own local ground (lower potential).

Piezo sparkers don't use electricity from an outside source, it's from a little rock inside the unit. My space heater uses piezo. That's not what I am talking about.

 

[K8MHZ]

If the spark generator has one side of its output connected to the metal frame of the furnace, then you are correct that no earth ground is needed.
OTOH if the low side is just connected to the neutral, but the spark is to frame metal then there will be a problem.

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This is pretty close to what I have:

Looking at the above, I guess the premises EGC isn't used, but the frame of the stove is the return back to the source.

I guess I just answered my own question. I think.....

 

[GoldDigger]

This is pretty close to what I have:

Looking at the above, I guess the premises EGC isn't used, but the frame of the stove is the return back to the source.

I guess I just answered my own question. I think.....

That should indeed work without any EGC or grounded piping. But capacitive coupling between windings of the igniter could easily trip a GFCI (or even AFCI if the current threshold is met by other loads).

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[K8MHZ]

Technically, isn't the output side of the igniter an SDS?

 

[GoldDigger]

Technically, isn't the output side of the igniter an SDS?

It appears to be, yes.

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[K8MHZ]

It appears to be, yes.

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So now, 're-draw' the stove with an EGC bonded to the frame going back to the panel and being bonded to the neutral. That would make the N side of the input electrically continuous with the grounded side of the output.

Do we still have an SDS when there is an EGC?

 

[K8MHZ]

From a troubleshooting standpoint, if I lose the connection from terminal 2 to the frame, the 2.3 amps to make the spark would flow through either the EGC or the metal gas line, correct? And it would do so at the voltage generated by the output? Like 10,000 volts?

 

[GoldDigger]

If you lose the connection between terminal 2 and the frame no current will flow and the voltage on the high terminal will be undefined.
The NEC definition of SDS specifically does not count indirect connection via EGC.

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[K8MHZ]

If you lose the connection between terminal 2 and the frame no current will flow and the voltage on the high terminal will be undefined.
The NEC definition of SDS specifically does not count indirect connection via EGC.

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My error. I meant from terminal 1.

 

[GoldDigger]

My error. I meant from terminal 1.

And I answered as if you had said 1.

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[K8MHZ]

And I answered as if you had said 1.

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Thanks!

 

[drcampbell]

Technically, isn't the output side of the igniter an SDS?

Technically, I'd think it's a cord-connected appliance since the only connection to the electrical system is through the cord & plug.
Whether it behaves like a separately-derived system probably depends on exactly what's inside the black box. It might be an autotransformer, in which case the secondary is not separate from the primary.

 

[kwired]

So now, 're-draw' the stove with an EGC bonded to the frame going back to the panel and being bonded to the neutral. That would make the N side of the input electrically continuous with the grounded side of the output.

Do we still have an SDS when there is an EGC?

Like any other SDS that is grounded - you have a common point to all systems through the grounded/grounding conductors, but secondary current is still trying to get back to the secondary side not the primary side.

Technically, I'd think it's a cord-connected appliance since the only connection to the electrical system is through the cord & plug.
Whether it behaves like a separately-derived system probably depends on exactly what's inside the black box. It might be an autotransformer, in which case the secondary is not separate from the primary.

If it were an autotransformer you will have GFCI issues if the appliance is supplied through a GFCI. Capacitive coupling and inductive kickback can still cause GFCI issues, possibly even sometimes on one that isn't protecting the stove.