Got a shock today! cowboy electricians fault

[bhm1712]

i was working on a jacuzzi for a friend today . the fault was the heater element which had stopped working and tripping out the rcd

started fault finding live, discovered that a flow switch was faulty which was on some auxilliary contacts on the main heater contactor. according to the wiring diagram the supply came in on the heating contactor and linked accross to other contactors in the panel to supply the pump and blower motors etc.

i isolated the supply by turning off the breaker in the panel. i tested for dead at the supply terminals - no voltage present. i took the cover off the flow switch and proceeded to remove the spade connectors from the terminals and there it was........came up my 2 fingers and up my arm. needless to say i didnt hold the connectors for long. my arm was aching like crazy, was one of the worst shocks i have had, apart from my 415 volt shock.

of course i tested for dead so i was wondering where the hell the electric supply came from.

turns out that the flow switch had failed before. the sparkie who came to look at it for some reason had discovered the fault but instead of fitting a new switch he had decided to add a new wire from before the main breaker, to the flow switch terminal which goes back to the auxilliary contactor. therefore the 230v was always present on the other side of the flow switch, operating the coil in the auxilliary to fool the system into thinking there was flow to allow the heater on!

once i sorted this hash up i discovered that one of the elements was down to earth. so not only was the flow switch inoperative, but the element was broken too

next time i will test for dead everywhere!!!!!! and i will never take wiring diagrams for granted!!

 

[Taylortwocities]

Well, you are very lucky.

My second thought is: why didn't the RCD trip?
Did you test its up to spec?

 

[bhm1712]

the RCD is fitted after the breaker in the panel, the extra wire was connected on the permanent live side of the breaker so the leakage would not have been detected by the RCD!

the panel is poor, the circuit is over complicated and wrong. i will completely rewire the panel this week to simplify everything as a lot of the wiring is not necessary.....and dangerous.

i just cant understand why i did not notice that although there was no continuity across the flow switch, that there was indeed 230v present. i have learnt a lesson today! i will no longer trust wiring diagrams when im not familiar with a panel. once i had understood the wiring diagram and i believed that there could not be any voltage there without the switch being closed i took it for granted and did not test for 230v

 

[RF Lighting]

I don't mean to sound harsh, but it is not the cowboys fault.

It is your fault for not properly testing for dead.

I expect you have probably learnt this the hard way now, but you must never ever trust anything, including switches, drawings etc, and you must test every single wire or connection before working on it, including retesting both wires if you split a connection incase there is a back fed neutral or something like that.

Oh and I'd be willing to put money on you not actually having had a "415V shock"

 

[333rocky333]

Quite often, parts that should not be live , become so in fault scenarios,
As well as like you found, due to incompetent work previously done.

Always test both inputs and outputs as standard practice.

In the last 2 days I have seen 3 different companies work in a 415 v and a 11 kv panel, without carrying out standard test procedures and I was quite shocked, as it's there lives they are risking.

 

[bhm1712]

yes i agree with you...it is my fault too. i assumed that because i isolated the supply that it was enough.

as for the 415 volt shock it was whilst i was at work. i work in a pharmaceutical factory with alot of electrical process equipment.

a forklift truck had reversed into a column on which a 3 phase cable was attached to. it had penetrated the cable and exposed 2 cores. i came along not knowing this at the time and stood talking to a mate. i had gone into the basement to fault find a pump which had stopped working. the column had a metal ladder rack attached to it. i was leaning on the column and holding the ladder rack. i then proceeded to touch the exposed cores with my right hand. i have never felt anything like it before. the cable was YY cable, but because the split in the cable was so minute it was not noticeable without looking in depth. it was found after the event. the circuit was not on an rcd but on 45 amp fuses. my mate said that i actually went completely white. our companies Health safety and environment department investigated along with our department and it was discovered that the red and yellow phase were exposed and it was likely that i had touched both cores with my right hand whilst my left had been touching the ladder rack

 

[bhm1712]

you may be right RF it could have been just 230 depending on whether i touched both phases or not..either way it felt horrendous. much worse than anything else i have experienced.

 

[RF Lighting]

How deep were the burns on your hand?

 

[Spark123]

I'd expect 415v across 2 fingers to give you severe burns.
Across 1 phase to a good earth across your chest would hurt!
The size of the supply fuse doesn't really matter, it only takes about 100mA to kill someone.

 

[holmslaw]

..

 

[plugwash]

out of interest what if anything was done about the 415V cable? unamoured cable carrying 415V in an area where heavy equipment is moving arround doesn't seem like equipment suitable for it's environment to me.

 

[bhm1712]

thanks for calling me a cowboy too!!! i never said i was perfect. i just did not imagine a permanent live to have been put in to the flow switch!

i had burned skin on my index finger only. it was not too bad, only like a soldering iron burn all the way up. sore for 4 days or so, more than anything was the constant cramp/ ache in my arm for a week.

the cable was removed and replaced with SWA cable and i was advised to claim compensation. i refused to claim as i did not blame my company.

 

[ban-all-sheds]

Across 1 phase to a good earth across your chest would hurt!

I can vouch from personal experience that 1 phase across your chest to a poor earth is no fun. I wouldn't say it was painful, but **** me is it ******* scary.....