street light bonding

[Legrand]

Hi everyone, I searched my title and couldn't find what I was looking for so I will ask.

For residential street lights we set a pull box next to the utility's box, put 10amp fuses in that box then run to the pole and place 3amp fuses, there is a ground rod at the pole and our pull box, so the pole, and the two rods are bonded together, but then the ground is not bonded at the utility, there is no neutral, this a 240v system. (I hope that made enough sense to piece it together) I know that during a line to ground fault it will not open the 10a fuses, energizing the pole, I feel that this is not a safe installation, I could be wrong and hope someone could explain this to me, or tell me how the rest of the world ties in their flat rate street light poles. (flat rate being that their is no service).

Thank you

 

[augie47]

Is there no ground in the Utility Box ?

 

[Legrand]

Yes, there is but for some reason the utility will not tie ours in with theirs, I just started on this job so I'm not asking to many questions. I just realized that no, there is no ground wire in
their box, only in the vault at the transformer where we also tie into at times but they still do not connect the two.

 

[Legrand]

There is a neutral in the utilities box, this is the box that feeds the homes adjacent to the street light, so I'm wondering if the norm is to tie the ground into the neutral providing a sufficient ground fault path back to xo in order to open the 10a fuses, or do you take the ground all the way back to the vault and bond to their ground. It needs to have an efficient path to open the circuit and I'm not sure how other municipalities are achieving this.

 

[dbuckley]

Essentially, you need to roll with whatever the PoCo supplies, but it has to be a safe supply arrangemnt.

You should have either a neutral from the PoCo and no ground, in which case you should have a N/G bond to your rods and pole (in normal terms, you've been given a service), or the PoCo should supply you a ground and optionally a (useless) neutral (ie they've given you a feeder).

Anything else is dangerous, and given this is a bonded poole, presumably where public walk, its particularly dangerous. The only safe way out of this other than wiring it correctly is a GFCI, and I'm certain I've never seen a GFCI on a streetlight on public ground.

 

[tryinghard]

There is a neutral in the utilities box, this is the box that feeds the homes adjacent to the street light, so I'm wondering if the norm is to tie the ground into the neutral providing a sufficient ground fault path back to xo in order to open the 10a fuses, or do you take the ground all the way back to the vault and bond to their ground. It needs to have an efficient path to open the circuit and I'm not sure how other municipalities are achieving this.

Usually with utilities if we install their circuits they inspect its there design, are you working from drawings? Street lighting is deffinately not ungrounded system type circuitry. If your point of connection is in this "utilities box" your EGC would connect with the grounded conductor (neutral) there, but again the utility is going to conrol where you terminate and they will inspect.

 

[don_resqcapt19]

When the utilities do this type of work they do not noramlly use an EGC. In most cases they only use a grounding electrode which is not safe. Sometimes they will use the grounded conductor as both the grounded and grounding conductor and connect it to the exposed metal parts.

 

[tryinghard]

?It needs to have an efficient path to open the circuit and I'm not sure how other municipalities are achieving this.

With these lower voltages they can only achieve an ?effective fault path? through a conductor, not earth alone. Ohm's law proves why, the earths resistance is unknown at any given moment therefor it is not an effective fault path, I=E/R reveals 9.6A if 25 ohms exists between the destination and the source XFMR in this case the short would remain and the fuse should not open.

 

[Legrand]

Thanks guys, this is all over this town in every residential neighborhood, I asked my boss about a ground fault condition and he said it would open the fuses, which I was pretty sure was not correct, now I know for a fact that it will not, I'm the new guy so I don't want to create a whole bunch of waves but this is only in residential (where all the kids play), so we all know it's wrong but I'm guessing that no one can force them to bond the circuit. Ah screw it I don't need this job that bad, I'm going to make a fuss.

thank all of you