Hydrogen fuel cell system grounding

[WiscElectrician]

Hello all,

We are currently installing a hydrogen fuel cell system as a trial run at one of our campuses. The 2500psi tanks will set next to a compressor, which then charges to 6500psi tanks that fuel the interior cells. Here is the question, per their requirements all of there components must be connected together to an electrode of not more than 25ohms to ground.

My thoughts were to hop off of the building riser loop which is bonded to the buildings steel around the entire building. There engineers then asked me to prove to them that the quality of that ground is not more than 25ohms to ground and were unwilling to take a reading from equipment to the building. Now I know you can check ground quality with the 4 point test prior to energizing the system ( because it could be completely isolated ). But what can I do to show them that a 12" iron PIV loop is a pretty impressive electrode?

Any help would be appreciated.

Thanks

 

[petersonra]

call someone who does this and have them do the tests and charge them for it.

the reality is that there is no way to know what the ground resistance is without measuring it and it may not be practical to get it to any particular value.

 

[augie47]

and... considering what you are dealing with, from a liability standpoint, I'd want as much "professional" documentation as I could get.

 

[don_resqcapt19]

and... considering what you are dealing with, from a liability standpoint, I'd want as much "professional" documentation as I could get.

I don't understand the need for a connection to a grounding electrode here.

 

[petersonra]

I don't understand the need for a connection to a grounding electrode here.

My guess is that it is one of those things that got into a spec and can not be removed without creating major hassles along the way.

 

[WiscElectrician]

My guess is that it is one of those things that got into a spec and can not be removed without creating major hassles along the way.

From my conversations, it's to get rid of static charges.

This came up because they wanted to drive ground rods at the outside cells, which is 50 feet from the building. My thoughts were rather than drill holes in the concrete and test the ground rods. To just bring one to them from the building. I have to get power to them anyways, so jumping off the nearest riser would be really quick and easy.

Thanks

 

[petersonra]

If it is solely to get rid of static charges, then simply bonding the metal parts together and a single grounding electrode is quite adequate.

25 ohms is just not necessary to deal with static charges. tens of thousands of Ohms is more than adequate.

 

[iceworm]

... My thoughts were to hop off of the building riser loop which is bonded to the buildings steel around the entire building.

... But what can I do to show them that a 12" iron PIV loop is a pretty impressive electrode? ...

I could do with a bit of education. What is a "building riser loop"? What is a 12" iron PIV loop?

The only google reference I saw that made any sense is a post indicating valve. So are you connecting to above ground 12" interior fire water piping? And the connection to earth is through fire water piping bonds to the building steel?

If so, how is the 12" PIV loop an impressive electrode?

If not, I could do with some education.

ice

 

[iwire]

Only part of a PIV is above ground and it connects to long, large underground pipes that run long distances.

Here is a good example.

 

[iceworm]

Only part of a PIV is above ground and it connects to long, large underground pipes that run long distances. ...

Ahh - thank you

And the fire water piping is 12"? That's pretty good sized pipe. Not that is bad, it is just out of my area of expertise.

Couple of more questions:

What little fire water piping I have installed (35 years ago) was 2" with Victolic (?) couplings - Grooved pipe ends, rubber gasket, steel clamp. In the example you show, the joints appear to be gasketed and clamped - certainly not welded. And the pipe appears to be coated.

Is this the normal UG construction technique?

No question in my mind this type UG piping construction method would measure a low resistance to earth, however:

Does the industry consider UG firewater piping a good grounding electrode?
Does industry consider interior firewater piping a suitable grounding electrode conductor?

Again, I'm not saying it is wrong. I just haven't seen it, so I'm asking.

ice

 

[iwire]

The indoor stuff with Victaulic type connections I would not count on.

Underground that I have seen is usually welded flanges bolted together.

 

[iceworm]

The indoor stuff with Victaulic type connections I would not count on.

Underground that I have seen is usually welded flanges bolted together.

Okay. And?

Does the industry consider UG firewater piping a good grounding electrode?

Does industry consider interior firewater piping a suitable grounding electrode conductor?

I'm thinking that if one is going to tell the people driving the spec, that connecting to interior firewater piping is more than acceptable, then one may have to answer these two.

And it could well be that everyone else knows that this is industry standard and it is just that I am out of my area.

ice

 

[don_resqcapt19]

If it is solely to get rid of static charges, then simply bonding the metal parts together and a single grounding electrode is quite adequate.

25 ohms is just not necessary to deal with static charges. tens of thousands of Ohms is more than adequate.

The IEEE Green Book says a connection of 1,000,000 ohms or less will prevent the build up of a static charge.

In this application, I would expect everything would be connected via metallic piping so there should be no need for any grounding connections, unless we are talking about the output of the fuel cell system. That would be a SDS and require grounding per 250.30.