Grounding / bonding a Transformer.

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When installing a 1.5 kva transformer 120v to a piece of equipment ( Welding Machine) tapping in to its 480v 3 ph power.Would you bond the neutral x1 or x2 to the ground conductor that is supplied in the dry type transformer!Or would you just tie the ground conductor supplied in to the ground that is supplied on the incoming 480v circuit. The transformer is to be wired into a recept. What would be the proper way to install a G.F.C.I recept.
 

bennie

Esteemed Member
Re: Grounding / bonding a Transformer.

Connect the primary and secondary equipment ground/neutral to the X-2 terminal, if secondary is only 120 volts. Bond enclosure to the X-2.

If you choose to call this a separately derived system,( I wouldn't) then you should run a ground electrode conductor to the nearest building steel or water pipe.

Connect GFCI in normal manner.

[ October 03, 2003, 07:55 PM: Message edited by: bennie ]
 

earlydean

Senior Member
Re: Grounding / bonding a Transformer.

What do you mean if you choose?
If you choose to call this a separately derived system,( I wouldn't) then you should run a ground electrode conductor to the nearest building steel or water pipe.
There is no choice, either the installation is a separately derived system or it is not.

Earl
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Re: Grounding / bonding a Transformer.

Earl,
There is no choice, either the installation is a separately derived system or it is not.
by whose definition. :D

Roger
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Grounding / bonding a Transformer.

Originally posted by earlydean:
What do you mean if you choose?

There is no choice, either the installation is a separately derived system or it is not.

Earl
I guess it depends if your area adopted the NEC or the BEC Bennies Electric Code :D
 

bennie

Esteemed Member
Re: Grounding / bonding a Transformer.

I recieved a reply from the NFPA, concerning my request for an official explanation of a transformer being a separately derived system and not just the power source for a separately derived system.

The response:

The definition in Article 100 has been determined to be a sufficient definition.

I replied "then you agree that a transformer is a power source for a system, if the system has no external connections.

No answer at this time.
 

Ed MacLaren

Senior Member
Re: Grounding / bonding a Transformer.

When I think of an electrical system I think of the following components-
1. Load devices,
2. A power source,
3. Connecting conductors, and
4. Control and protective devices

What would be the purpose of a power source (transformer or generator) without load devices to operate?
And load devices will not operate without a power source.

Any given system's power will be derived from the facility's main service transformer, or, if it is required to be of a different characteristic (voltage, frequency, DC, etc.) it will be separately derived.

Where's the controversy?

Ed

[ October 04, 2003, 06:03 PM: Message edited by: Ed MacLaren ]
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Re: Grounding / bonding a Transformer.

Ed, Bennie said
Connect the primary and secondary equipment ground/neutral to the X-2 terminal, if secondary is only 120 volts. Bond enclosure to the X-2.
this being the case we have physical connection, therefore one system different voltages. (auto transformer)


Roger
 
Re: Grounding / bonding a Transformer.

Thanks for the input guys you are verry helpful and I really appreciate your advice. So let me get this straight so I tie the neutral side of the transformer to case ground , my incoming ground and ground supplied in the transformer.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: Grounding / bonding a Transformer.

The existing definition is clear and states that there not be a direct connection of a solidly grounded circuit conductor to a similar conductor in another system. Connections of these conductors to a common grounding system are not connections of the circuit conductors directly to each other.
The above is CMP 1's statement on proposal 1-135.
Don
 

bennie

Esteemed Member
Re: Grounding / bonding a Transformer.

CMP-1 has not traced the origin of separately derived system.

I am planning to file an ex-parte suit demanding a hearing on this issue.

I have written proof from the NFPA's own archives, that the opinion is in error.

[ October 06, 2003, 02:34 PM: Message edited by: bennie ]
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: Grounding / bonding a Transformer.

Bennie,
It doesn't matter if they have traced the orgin or not. The statement above is the official position of the NFPA on this issue. It is their code and they can write it anyway that they want to. What the term SDS originate from or what it means to you, or what it should mean has no bearing on the issue. The statement of CMP 1 is the official word on what this section means in the 2002 code.
Don
 

electrifried

New member
Re: Grounding / bonding a Transformer.

It seems to me that if an auto xmfr is used there is a direct electrical connection and therefor does not fit the definition of a seperately derived system.
 
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