These are Stories that were published in PEI Safety Letters or were told to us by anonymous persons.
Three men were removing a gasoline dispenser from a dock at a marina. As the dispenser was being lifted, the disconnected wires sparked because of feedback from another dispenser that was just connected. Fortunately, the spark did not ignite the gasoline vapors. In the future, electricity to the entire fuel system will be shut down before work begins.
PEI Safety Letter
A recent SafetyLetter described an accident where disconnected wires sparked because of feedback from another dispenser. To alleviate future problems of this nature, a member suggested that each dispenser be put on its own circuit breaker, or that relays be used. Electronic devices are also manufactured to eliminate this type of feedback in submersible control wiring. At marinas, the grounding of the electrical system is extremely important.
PEI Safety Letter
One of our experienced service technicians was called out to service a dispenser located at a very busy retail service station. The dispenser would not reset or turn on while other pumps dispensing the same product were working. He logically assumed that the problem was in the reset and noticed the dispenser had been leaking around the meter and pilot valves.
The manager of the station did not agree to turn the power off and shut down all unleaded dispensers, so our technician started to open the power reset with the electricity on. Before he could get the cover completely off, an explosion occurred. The reset was blown apart, the serviceman's glasses were shattered and the dispenser was engulfed in flames. Our man's extinguisher and the fire extinguisher at the station were insufficient to put the fire out. The fire department was called and the firemen put out the blaze.
The dispenser was completely destroyed. The hose on an adjacent dispenser burned. The paint on two cars parked nearby blistered on one side. The technician had the hair on the front of his head singed off. He had to have stitches in his cheek and a piece of aluminum removed from his shoulder. If he hadn't been wearing his glasses, the serviceman would probably have lost his sight. Our servicemen are instructed to use their own good judgment and not bow to the wishes of the station manager. If, in doing so, a safety problem would be avoided.
PEI Safety Letter
A customer at a large service station with multiple gasoline dispensers drove into one of the dispensers, knocking it over. The attendant hit the emergency stop and called the fire department. The fire department allowed the station to open half of the dispensers because there were two gasoline consoles. A service contractor was called to repair the station. In the meantime, a customer began dispensing premium gasoline at one of the other dispensers. Electrical feedback reached the damaged dispenser igniting fuel vapors. The flames caused severe damage to both the dispenser and the canopy. The fire department had to return to put out the fire.
Fortunately, nobody was injured because the station attendant activated the emergency stops, which shut down all the power. The pumps at this station had been installed within the last year. If the contractor and electrical inspector had been aware of the 1999 National Electrical Code change (see Article 514-6, Provisions for Maintenance and Service of Dispensing Equipment, effective January 1, 1999), they would have installed a device that would have prevented feedback.
PEI Safety Letter
RSEC Comment: This accident brings up several issues.
Was the new electrical code adopted and being enforced in the municipality in which the service station was located? Sometimes, this is a 1- 2 year process.
What type of device was being used to eliminate feedback? Some devices will eliminate feedback completely while others require some sort of human intervention (turn off a switch) to eliminate feedback.
Did the fire department or attendant know what type of isolation system was installed? Probably not, it is not their responsibility to know all the inter-workings of a service station.
If this service station had a device to eliminate feedback was it marked as such a device?
Unfortunately there is no standard method of eliminating feedback in submersible pump control wiring. Some methods of wiring remove it manually, some remove it automatically but only in certain dispensers, and the best remove it completely.
A sevvice technician was troubleshooting a submersible turbine pump (STP). The technician was using a screwdriver in an attempt to push in on the relay to take readings. The screwdriver slipped and made contact with a hot wire and ground causing the shunt trip to trigger the fueling equipment circuit breaker in the main panel. This caused the entire refueling site to go down which resulted in lost sales, a damaged relay, startled employees and disturbed customers. The incident could have been avoided by using proper procedures for diagnosing submersible pump problems. The proper procedure would have been to energize the submersible motor by authorizing it at the dispenser or by pushing in on the relay with a nonmetalic object.
PEI Safety Letter
RSEC comment: Had our EDC been installed at this location it would have been an easy test. In our EDC there is a "Manual - Off - Auto" switch for each product and the switch could have been put into the momentary manual position to energize the relay. The technician could have done all his testing right there safely.
A service technician found a pair of diesel 3HP submersible pumps in a truck stop that were running constantly. He determined that part of the problem was bad wiring (the wiring was done by an electrician that had no experience with service stations or truck stops) and these submersible pumps were controlled by a timer that made them alternate every 12 hours. The management was informed that there were problems and advised them on the necessary repairs. They ignored the technicians advice and the repairs were never done. That was over 2 years ago.
Problems popped up again when it was necessary to do the annual line and leak detector testing. This time it had to be fixed, and because the wiring was in such bad shape the only way to check the submersible control wiring was at the dispensers with the power on. Each one of 8 dispensers were checked, and one dispenser kept the submersible pump on all the time, and another would never turn on the submersible pump at all. Because one dispenser was always on, the problem with the other dispenser that never turned on was never noticed. That was over 6 months ago.
Just recently, over a weekend, problems popped up again this time no diesel fuel could be pumped at all. Submersible pump No. 2 was on continuously, this time because the alternating timer had been left on manual and after a week and a half and the motor starter relay coil finally burned out. Submersible pump No. 1 was out already because its' starter relay coil had burned out two weeks earlier and a new one could not be located. A qualified electrician was called in to try and repair/replace the submersible motor relays to get them pumping again.
Repairs and down time have cost this truck stop many times the cost of correcting the wiring.
RSEC Comment: Servicing this equipment could be made much easier if our EDC was installed at this truck stop. This would give the technician a diagnostic tool he could use for servicing, and also the truck stop has the benefit of not being shut down during servicing.
Update: One of our EDC's has been installed at this truck stop and they have not had any problems since.
A truck stop had just finished installing new dispensers and there were some minor problems that had to be repaired on the dispensers. One dispenser had a bad meter and it needed to be replaced.
A technician closed the emergency valve for that dispenser so the meter could be replaced. When the flange bolts were loosened an O-ring blew out and fuel sprayed out all over the drive. One of the technicians ran inside the building to turn off the emergency switch and ran back outside again to find out the fuel had not stopped. He ran back inside again but this time to the electrical room (which was normally locked) and turned off the circuit breakers to the submersible pumps, this stopped the fuel.
After investigating what happened a piece of fiberglass was found caught in the emergency valve and not allowing it to close properly. Later the truck stop owner had his electrician check the emergency switch wiring and found nothing wrong with the way it was wired. Another technician was called to check the dispenser operation and its wiring. He found one dispenser with a bad relay board that kept the submersible pump running all the time. Possibly this had something to do with the emergency switch operation.
RSEC Comment: If our EDC were installed at this truck stop the bad relay board could have been found with the EDC's diagnostic features. It would not eliminate the fuel spill but it is possible the emergency switch would have operated properly.
Four new dispensers were installed in a newly remodeled service station. The owner was asked if she would want to install one of our EDC's. After some discussion and after checking with the electrician she said "No", because her electrician was going to install his own isolation relays.
When the dispensers were started up the electrician had not installed the isolation relays. Three dispensers worked fine but when the fourth was turned on all the dispenser relay boards were blown out along with part of the electronic line leak detection system.
It was determined that one dispenser was out of phase and when that dispenser was turned on with any other dispenser there was 240 volts in the submersible control wiring causing all the relay boards to be blown out. We heard that this cost the electricians insurance company about eight thousand dollars. The dispenser technician made several trips to this location for repairs to the dispensers caused by this incident.
RSEC Comment: Don't start up dispensers without isolation unless you have good insurance. Isolating submersible control wiring is not required by any, but recommended by some dispenser manufacturers. The burden is put on the startup person to make sure the wiring and phasing is correct.