I almost killed myself. What an idiot

My take on this one would be, before you start working on electrics (230volts) boat mains buy a multi meter (MM). I like the ones that have the clamp meter to test load (amps) pay about £50.
First thing is to make the circuit live. Check & see if there is 230v on the MM and if not check another circuit to make sure the MM is working. If you can then make the circuit live ( reset circuit breaker ) Then if you have 230v put a link from neutral to earth & this should trip the residual-current circuit breaker (RCCB) on boat or pontoon then isolate / tape off the RCCB. You can get very cheap lock off units for MCBs or RCCBs but most domestic situations insulation tape over the RCCB & mains unplugged or main isolator on boat switched off. Then test for 230v to make sure circuit is safe. BEFORE working / carrying any work on an electrical circuit.
 
penberth3 said:
First check your tester on something you know is live, then check the circuit you're working on, then check the tester again on a known live.

Edit: Superheat says the same thing above.
Click to expand...

It is called “proving” ie prove your meter works, get a reading on a live circuit, isolate (this is a physical disconnection, like removing the shore cable or provide a lock) check for circuit being dead, then PROVE you meter still works by testing on a known live or a proving unit (small battery 230 v ac supply giving only enough current to make the meter register.)

This does assume that the meter is digital, if you have a meter with an analogue indicator tie something heavy round it and throw it in the sea
 
simonfraser said:
haha, noooooo the idea is to isolate it FIRST
then double check with the pliars rather than your fingas !!
Click to expand...

Don’t ever short a live terminal to earth or Neutral. If it just happens to still be live, the current can instantly reach hundreds of amps. This is enough to blow holes in pliers. The metal which was in the hole in said pliers is now small particles of molten metal which can burn straight through eyeballs.
The trip or fuse will eventually (even 30 msecs is a long time) disconnect the supply but not before the damadge has been done
 
Just as in real life, this forum seems to substantiate the view that when you get five so-called experts in a room together, you will end up with at least seven different opinions.

What pisses me off very slightly is that some people on here either don't bother to read the whole thread through first before commenting; or they do, then regurgitate previous comments as if they thought of them first.
 
JerryC said:
Just as in real life, this forum seems to substantiate the view that when you get five so-called experts in a room together, you will end up with at least seven different opinions.


What pisses me off very slightly is that some people on here either don't bother to read the whole thread through first before commenting; or they do, then regurgitate previous comments as if they thought of them first.
Click to expand...

Some think they are right, some are qualified.
Read through the whole post, then confirm and add to
 
Rocksteadee said:
It is called “proving” ie prove your meter works, get a reading on a live circuit, isolate (this is a physical disconnection, like removing the shore cable or provide a lock) check for circuit being dead, then PROVE you meter still works by testing on a known live or a proving unit (small battery 230 v ac supply giving only enough current to make the meter register.)

This does assume that the meter is digital, if you have a meter with an analogue indicator tie something heavy round it and throw it in the sea
Click to expand...

Haha, and if it's an AVOmeter you could use it as a heavy weight to hold something else down. (Just kidding, they've probably all died by now.)
 
penberth3 said:
What exactly is the problem with analogue meters?
Click to expand...

They have a place in an electronics workshop due to their inherent damping which can show a slow response. They have too high an internal resistance to register an electronic proving unit. If you really like the action of amn analogue display buy a decent Fluke which has a digital analogue display
 
Rocksteadee said:
They have a place in an electronics workshop due to their inherent damping which can show a slow response. They have too high an internal resistance to register an electronic proving unit. If you really like the action of amn analogue display buy a decent Fluke which has a digital analogue display
Click to expand...

At the risk of being flamed twice in one week about electrical stuff, I don't think your second sentence is quite right. Analogue meters were typically 50 micro amps full scale deflection., DVMs have a much higher input impedance, therefore do not load the circuit being tested so much. The sample and hold circuit at the front end of the A to D converter may cause a problem in very very delicate circuits like I used to work on when microprobing failed ICs but this won't be a problem for people testing out their boat electrics.
 
JerryC said:
At the risk of being flamed twice in one week about electrical stuff, I don't think your second sentence is quite right. Analogue meters were typically 50 micro amps full scale deflection., DVMs have a much higher input impedance, therefore do not load the circuit being tested so much. The sample and hold circuit at the front end of the A to D converter may cause a problem in very very delicate circuits like I used to work on when microprobing failed ICs but this won't be a problem for people testing out their boat electrics.
Click to expand...

I stand corrected got high and low back to front and used resistance as unless you have worked with electronics impedance is normall y meaningless
 
sorabain said:
Out of interest, is the general procedure to first check that your "live line detector" still works by testing it when the line is expected to still be live, then isolate and try again? Just wondering how you tell the difference between "not live" and "handheld broken". I had some excitement in the past from someone bodging and bypassing mains in my house :|
Click to expand...

It depends on your indicator as many more expensive types have a self check or test facility to test the unit before use. If you wish to test yours on a known live line first and then isolate and test again then I see no problem with this self checking as sensible people would rather check twice than not at all.
 
On small boats I have taught my apprentice to " take the lead", i.e. disconnect from the shore and take the plug end into the cockpit or saloon with him so he can see it. Then carry out his checks. That way, there is very little chance of it being plugged back in by a "helpful" marina staff.

Large boats I have a lockout kit on the van, and most vessels have lockout kits next to any electrical work areas. Padlocks only have 1 key and the owner of the works takes the key with them.


As already mentioned, get a decent multi meter and know how to use it. And know if your boat has additional feeds such as an inverter and know how to isolate them.

Stay safe.
 
You must log in or register to reply here.

Share this page

Top