Confirmation on advice

[ccam108]

Hi all

My mate posted on Facebook about some disco lights he was repairing and received a 240V shock while doing so.

Untitled

• ccam108
• 8 Oct 2010
• 1

From what I've heard one of the internal PCBs was poorly mounted and fell onto the case, causing it to become live. However, in the photos the case has an earth connection, which should have caused the fuse to blow instantly.

Is my advice there correct? My thinking is that there is a major problem with the earthing somewhere in the shop!

Colin C

 

[londonboy]

He shouldn't have been working on it live anyway.

 

[ccam108]

He shouldn't have been working on it live anyway.

That much is obvious, but it sounds like there is no earth in his workshop sockets!

 

[electronicsuk]

I've only read your post and not looked at the image, but yes, if the fitting is class I and has an earth connection to the case, then it is unlikely that a severe shock should have been received. The touch voltage on the casing should have been limited to a maximum 50v. This does not mean the fuse/breaker protecting the circuit would cut the power instantly, mind.

There could be many issues, from the fixed wiring to incorrectly wired plug to break in the flex to the fitting. If your friend does this sort of work for a living then he's a fool not to at least have an RCD protecting the circuit, or better yet, work through an isolation transformer. Either of these can be achieved without the need to update the entire installation for the sake of providing a couple of sockets on the test bench.

 

[ban-all-sheds]

If your friend does this sort of work for a living then he's a fool not to at least have an RCD protecting the circuit, or better yet, work through an isolation transformer.

He's a fool anyway.

Firstly for working live, and secondly by doing that sort of work in the first place when he clearly doesn't understand electrics.

 

[Jaymack]

Hi all

My mate posted on Facebook about some disco lights he was repairing and received a 240V shock while doing so.

While posting? Was it from the keyboard? I don't think so, especially if a battery one.

Regards

 

[Spark123]

The touch voltage on the casing should have been limited to a maximum 50v.

Touch voltages can exceed 50v but the supply should automatically disconnect rapidly, typically in less than 0.4s.

 

[RF Lighting]

Maybe he's wrong and didn't actually get a mains shock like he thinks he did?

Could've been static, could have been as a result of direct contact, who knows, but it's unlikely RCD protection would have made much if any difference at all here.