S
scary cakes
Hi All,
I attended a welders yard today with numerous electrical problems.
Very old insatallation in poor condition, never had a PIR and no sign of any maintenance, a total mess.
Firstly they had a large 3 phase pillar drill whose metal casing went live when switched on. I found a short between a phase and earth from the commando plug which would explain the fault but why did it not blow the fuse? Old MEM DB, rewireable fuses.
Secondly they had a cooked earth cable within a control box for a large saw. Apparently, the staff told me they were welding nearby when it started to cook and it stopped when they finished welding. the commando in which the welding unit was plugged into and the saw supply are on separate curcuits.
They went on to tell me they previously had a drill plugged into a switched on 13a socket resting on a table not being used whilst on the same table they started welding, the cable from plug to drill started to burn out.
The yard is in a semi-rural location and at first glance it appeared to be a TT, as there is a tatty old approx 10mm cable running from the MET to the factory floor and is then untraceable, however there is a 10mm earth terminated into the neutral block at the head which would suggest PME. We attempted to get confirmation from the LEB as to the supply earthing type but to no avail.
I have taken loops at head, main switch, isolators and commandos and the reading are from 0.28 Ohms to 0.53 Ohms, acceptable.
I have also disconnected the suspected earth rod fly lead and taken a EFLZ and it was 1683 Ohms.
We suspect that it may have been TT originally and due to a poor earth perhaps they decided to jab into the neutral, but its not designed for PME.
To be honest really not sure.
Can anyone help is there a way I can determine the supply type?
Any help is appreciated.
I attended a welders yard today with numerous electrical problems.
Very old insatallation in poor condition, never had a PIR and no sign of any maintenance, a total mess.
Firstly they had a large 3 phase pillar drill whose metal casing went live when switched on. I found a short between a phase and earth from the commando plug which would explain the fault but why did it not blow the fuse? Old MEM DB, rewireable fuses.
Secondly they had a cooked earth cable within a control box for a large saw. Apparently, the staff told me they were welding nearby when it started to cook and it stopped when they finished welding. the commando in which the welding unit was plugged into and the saw supply are on separate curcuits.
They went on to tell me they previously had a drill plugged into a switched on 13a socket resting on a table not being used whilst on the same table they started welding, the cable from plug to drill started to burn out.
The yard is in a semi-rural location and at first glance it appeared to be a TT, as there is a tatty old approx 10mm cable running from the MET to the factory floor and is then untraceable, however there is a 10mm earth terminated into the neutral block at the head which would suggest PME. We attempted to get confirmation from the LEB as to the supply earthing type but to no avail.
I have taken loops at head, main switch, isolators and commandos and the reading are from 0.28 Ohms to 0.53 Ohms, acceptable.
I have also disconnected the suspected earth rod fly lead and taken a EFLZ and it was 1683 Ohms.
We suspect that it may have been TT originally and due to a poor earth perhaps they decided to jab into the neutral, but its not designed for PME.
To be honest really not sure.
Can anyone help is there a way I can determine the supply type?
Any help is appreciated.
