Is this a safe scenario?

[cavejumper]

Hi everyone, I would appreciate your opinions regarding the safety of a wiring scenario I've been asked to install at my church. Keep in mind this will be a temporary install for a weekend activity.

My church building is located in a rural area beside a small stream. Across the stream is a hill upon which some members would like to set up a water slide during the annual church campout. To do this, one guy has a submersible pump (think well pump) that can be set in the stream to pump water to the top of the slide. I imagine the distance from the church building to the top of the slide is too far to allow us to easily pump water from the church - it's several hundred feet away.

The reason I question the safety of this setup is because there will be kids playing in the stream while the pump is energized. The only structure in the vicinity of the stream is a wooden bridge that crosses it, otherwise, there are no docks or anything similar where there would be a difference of potential. Certainly no other source of electricity nearby. Is there a way to ensure this will be a safe scenario? I would control the pump by a switch near the pump that disconnects all ungrounded conductors, and I can feed it off a GFCI breaker. Is that sufficient, or is there more that should be done? Would it make a difference to run the pump off a generator instead of utility power? Or should the whole idea be abandoned?

A couple of years ago I would have set this up the way I stated above, but I've become more knowledgeable and safety aware since then, and I realize I need the advice of people more experienced than I in this case. I appreciate your feedback!

 

[Jraef]

Using a generator makes no difference in safety, you can kill someone with a generator just as easily as with utility power. Not sure why you would think that...
If you were thinking of a generator, then if you really want it to be electrically safe, use that engine to run the pump directly, no electric motor at all!

A GFCI would render it safer, but most likely it will be constantly tripping unless everything is PERFECT. A submersible pump likely isn't going to cut it, you will need to have the pump on land and pumping via pipes, think swimming pool pump system. But has anyone even bothered to work out the hydraulics here yet? Pumping a significant amount of water up a hill from a stream might take more HP than you think. I'd still think an engine driven pump would be better all around and if you don't like the idea of gasoline and kids (I don't), use propane.

 

[kwired]

What the generator does do is eliminate the possible voltage rise issues originating from grounded service conductor/POCO MGN.

If the pump is located away from the slide users, I don't see how this would be any different from electrical safety perspective at the slide area then using the (presumed because it is a rural church) well pump back at the church building, or even having a booster pump in a line that feeds over to the slide.

 

[charlie b]

Trying not to be too disturbing here, but how are you going to prevent this system from pumping small fish onto the slide? I can imagine a violent reaction from a child who suddenly sees a fish on their lap. Not a good thing to happen when the child is at the top of a slide.

 

[nickelec]

Trying not to be too disturbing here, but how are you going to prevent this system from pumping small fish onto the slide? I can imagine a violent reaction from a child who suddenly sees a fish on their lap. Not a good thing to happen when the child is at the top of a slide.

How about a screen?

Sent from my SM-G950U using Tapatalk

 

[K8MHZ]

Trying not to be too disturbing here, but how are you going to prevent this system from pumping small fish onto the slide? I can imagine a violent reaction from a child who suddenly sees a fish on their lap. Not a good thing to happen when the child is at the top of a slide.

That would make for a classic home video.

I love AFV. Especially when there's fish.

 

[cavejumper]

Yeah, there would be screen of some sort around the pump to keep fish and debris out.

Kwired, I don't have any concerns with the people using the slide, rather, the people who would be in the stream near the pump while it's energized.

Jraef, as far as the hydraulics of this situation, they have set this up the way I described several years ago and it worked well. Now they want to use it again, and I want to make sure it's safe since I'm the one they asked to set it up. It wasn't on a GFCI breaker before, however, so you may have a point that using one won't work well.

Am I right to be concerned with hooking this up? Or am I being overly cautious? Is there a good way to make this electrically safe? If not, I'll recommend using a pump on land.

I appreciate all of your input so far, thank you!

 

[Jraef]

Well, just because they haven't killed someone YET, doesn't make it safe to keep trying...

If it were me, and I felt somehow compelled to at least TRY to make it safer than it was, I would use a GFCI. If it nuisance trips, you KNOW it was unsafe to begin with and should never have been done in the first place. If you are really fastidious about all your connections and seals, and the pump windings are in good shape, and everything goes perfect so it does NOT trip, then you are the hero.

 

[USMC1302]

Do you have a nearby volunteer fire dept? They could train on drafting from the creek, and provide another source of entertainment for the kids.....just a thought. I've done stuff like that before.

 

[kwired]

Trying not to be too disturbing here, but how are you going to prevent this system from pumping small fish onto the slide? I can imagine a violent reaction from a child who suddenly sees a fish on their lap. Not a good thing to happen when the child is at the top of a slide.

Your typical submersible well pump doesn't have large enough openings in the inlet screen, if it did the multistage impeller would pulverize the fish anyway, there is no clearance for it to pass through in one piece.

 

[kwired]

Yeah, there would be screen of some sort around the pump to keep fish and debris out.

Kwired, I don't have any concerns with the people using the slide, rather, the people who would be in the stream near the pump while it's energized.

Jraef, as far as the hydraulics of this situation, they have set this up the way I described several years ago and it worked well. Now they want to use it again, and I want to make sure it's safe since I'm the one they asked to set it up. It wasn't on a GFCI breaker before, however, so you may have a point that using one won't work well.

Am I right to be concerned with hooking this up? Or am I being overly cautious? Is there a good way to make this electrically safe? If not, I'll recommend using a pump on land.

I appreciate all of your input so far, thank you!

Even with GFCI protection you need to keep people away from the pump if they are swimming in the same body of water the pump is in. Any voltage rise on the EGC will be a shock hazard around the thing, and a GFCI will not protect from that, normal voltage drop on your service neutral will cause a rise on the EGC to the surrounding earthed items. This won't matter if the pump is submersed in the water or if it is a jet pump on the shore either, any bonded piping into the water will still be at same potential as the EGC supplying the pump.

 

[Jraef]

New wrinkle I just thought of in your river pump scenario, you had better research what's called the "VBGA", an acronym for the Virginia Graeme Baker Act (named for a little girl who drowned) regarding pool and spa safety, later amended to include rivers and ponds where pumps are involved. It basically requires that pumps be designed or fitted with accessories that prevent people from getting trapped under water by pump suction and drowned, including having long hair sucked into the screen. It might just be better all around that if that pump is in the stream, the area is locked and fenced off to keep kids out.

 

[cavejumper]

Thank you all for your helpful responses! I believe I'll recommend using a jet pump on land with nonmetallic piping into the stream. I'll mention using an engine driven pump, but I think they'll still prefer the electric motor for quietness and ease of use.

 

[MichaelGP3]

Don't know if your picnic already happened.....

Don't know if your picnic already happened.....

Thank you all for your helpful responses! I believe I'll recommend using a jet pump on land with nonmetallic piping into the stream. I'll mention using an engine driven pump, but I think they'll still prefer the electric motor for quietness and ease of use.

Anyway, maybe next year think about erecting a temporary aboveground pool (assuming there is a safe location) with a 2" hose with a valved nozzle connected to the drain. Turn your pump off via it's disconnect when the pool is full or before folks start using the waterslide. About the quietest it can get.

 

[Sahib]

Even with GFCI protection you need to keep people away from the pump if they are swimming in the same body of water the pump is in. Any voltage rise on the EGC will be a shock hazard around the thing, and a GFCI will not protect from that, normal voltage drop on your service neutral will cause a rise on the EGC to the surrounding earthed items. This won't matter if the pump is submersed in the water or if it is a jet pump on the shore either, any bonded piping into the water will still be at same potential as the EGC supplying the pump.

I believe proper bonding would eliminate EGC potential rise hazard.

 

[dionysius]

Not my area so I may be way off but isn't this the same electrical setup as found in swimming pools????

 

[kwired]

I believe proper bonding would eliminate EGC potential rise hazard.

Voltage rise on the grounded service conductor or even the POCO MGN, which are both (though somewhat indirectly in the case of POCO MGN) bonded to the EGC will result in same rise above ground on all objects bonded to the EGC, which is the reason we must perform equipotential bonding in swimming pools. Yes bonding will eliminate potential rise hazard but where do you stop providing the bonding, there will always be a rise over true ground at the boundary of what you have bonded.

Not using grounded conductors for normal current carrying functions is the most you can do, but still need isolation from any upstream separately derived system grounded current carrying conductors also or there is still some risk.