bonding Water pipe Dielectric fittings

[brother]

its been a while since ive wired some old houses. I thought you had to use a special type of bonding clamp for when you going from Galvenized pipe to copper when bonding them together with a copper wire when you have a 'dielectric' fitting between the 2. this pipe (galvenized) is 5ft with in the building and yes you do bond at the panel too for it to be a GEC.

Heard a guy say that this would just defeat the purpose of the dielectric fitting to prevent the dissimilar metals from corrosion. I said well you still have to bond it anyways, either a copper wire to the panel from the galvenized pipe on the one side of the dielectric fittings and then bond the new copper water pipe (ie from the water heater) to the panel. all that copper water pipe has to be bonded, so either way you still have to bond.

But tell me what fitting would you use to jumper over dielectric fitting from the copper to galvy water pipe that would prevent corrosion if you wanted to do it this way????

 

[resistance]

deleted (duplicate)

 

[resistance]

its been a while since ive wired some old houses. I thought you had to use a special type of bonding clamp for when you going from Galvenized pipe to copper when bonding them together with a copper wire when you have a 'dielectric' fitting between the 2. this pipe (galvenized) is 5ft with in the building and yes you do bond at the panel too for it to be a GEC.

Heard a guy say that this would just defeat the purpose of the dielectric fitting to prevent the dissimilar metals from corrosion. I said well you still have to bond it anyways, either a copper wire to the panel from the galvenized pipe on the one side of the dielectric fittings and then bond the new copper water pipe (ie from the water heater) to the panel. all that copper water pipe has to be bonded, so either way you still have to bond.

But tell me what fitting would you use to jumper over dielectric fitting from the copper to galvy water pipe that would prevent corrosion if you wanted to do it this way????

Use a galvanized grounding clamp for the galvanized, and use a copper grounding clamp for the copper.

 

[brother]

Use a galvanized grounding clamp for the galvanized, and use a copper grounding clamp for the copper.

Im not sure you understood my question, so say you use the galvanize clamp on galvanize, and copper on copper pipe, do you still use a copper wire to run the jumper between the 2 when they are connected by a dielectric union??

 

[quogueelectric]

Most commonly I see dielectric fittings on electric H2o heaters to prevent galvanic action.

 

[brother]

Most commonly I see dielectric fittings on electric H2o heaters to prevent galvanic action.

Yes this true, so goes my question "

tell me what fitting would you use to jumper over dielectric fitting from the copper to galvy water pipe that would prevent corrosion if you wanted to do it this way????"


Do you have an answer?? I ve seen this debate on other forums, from Mike Whitt and others.

http://www.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=11;t=001354

 

[e57]

Use a galvanized grounding clamp for the galvanized, and use a copper grounding clamp for the copper.

The second one there is a bronze clamp and good for either type of pipe IMO. Bronze is pretty inert... Depending on the screws (Bronze as well) you can bury them.

The other is dual-rated for use with AL conductors and both types of pipe.

www.electrix.it/cataloghi/fci/burndygr.pdf

OP's question - bronze DB ones IMO.

 

[M. D.]

3 questions ,.. do you know if you have ten feet of pipe in contact with the earth?? My guess is your pipe has pretty much become earth..
Are we required to extend the water pipe electrode 5' into the structure??
Or did I read it wrong and the water service has been changed to copper and the interior is Galvy

 

[don_resqcapt19]

The corrosion issue is only a problem with the direct physical connection of dissimilar metals. As long as you use a suitable clamp for each type of pipe there is no problem, assuming that the bare copper jumper is not in direct contact with the galvanized pipe.

 

[brother]

If you where to put a jumper around an intentionally installed die-electric union you would be defeating the purpose of the die-electric union

http://forums.mikeholt.com/showthread.php?t=100815

This is a quote from Iwire from another post. so does he think this would defeat the purpose in a water pipe too??

 

[don_resqcapt19]

Brother,
The issues with the water pipe and the gas pipe are totally different. With the gas pipe there are two issues, one is creating a parallel path for the grounded conductor current which can create a spark hazard for the gas utility workers and the second is that if the metal underground gas pipe has a cathodic corrosion protection system a connection to the electrical grounding system will reduce or defeat the corrosion protection.
The only issue with the water pipe is the local corrosion that can occur with dissimilar metals in close proximity.

 

[resistance]

The second one there is a bronze clamp and good for either type of pipe IMO. Bronze is pretty inert... Depending on the screws (Bronze as well) you can bury them.

The other is dual-rated for use with AL conductors and both types of pipe.

www.electrix.it/cataloghi/fci/burndygr.pdf

OP's question - bronze DB ones IMO.

That's true!

 

[brother]

Brother,
The issues with the water pipe and the gas pipe are totally different. With the gas pipe there are two issues, one is creating a parallel path for the grounded conductor current which can create a spark hazard for the gas utility workers and the second is that if the metal underground gas pipe has a cathodic corrosion protection system a connection to the electrical grounding system will reduce or defeat the corrosion protection.
The only issue with the water pipe is the local corrosion that can occur with dissimilar metals in close proximity.

so would you say its 'required' to have a jumper on the water pipe where a dielectric union is used??

 

[don_resqcapt19]

so would you say its 'required' to have a jumper on the water pipe where a dielectric union is used??

You are required to use the metal undergound water pipe as a grounding electrode if it is in contact with the earth for 10' or more. You are required to bond the interior metal water piping system. In many cases the combination of these rules will require a bond around a dielectric union.

 

[M. D.]

I would bond right around that union and not loose a wink of sleep. or just bond the interior piping somewhere else ,.. but if this union is effecting the 10' length of electrically continuous water pipe in contact with the earth It must be bonded around.

This was written by Mark Ode back in 2000 in regard to making the water pipe electrode electrically continuous for 10' in the earth ..

.......The metal piping system must be, or be made, electrically continuous by bonding around any insulating joints or
nonmetallic pieces of pipe that may interrupt the continuity of the metal pipe. For example, a dielectric union may
have been installed in the metal water pipe to convert from galvanized or black steel pipe to copper. The dielectric
union provides an insulator between the two different metal piping systems to counter the effects of galvanic
corrosion or cathodic action (one metal acting as a sacrificial element to the other metal). This would otherwise
result in deterioration of one or the other pipes.
The movement of water, acting as an electrolyte, past the two dissimilar metals causes a small DC voltage and
thus current flows at the junction or coupling of the two metals.
The small DC current that results is similar to a battery (one of the metals becomes an anode and the other a
cathode) with eventual breakdown of one of the metals due to the resultant chemical reaction. Since the dielectric
union insulates one length of pipe from the other at the connection point, a bonding conductor must be installed
around the insulator. A small amount of current may still occur with the bonding jumper, but the cathodic effect is
minimized.

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