Floor sander breaker RCD issues

[simonpdl]

Been employing a floorer to sand and oil the floors and for the last two days the large floor sander has been working fine.
Yesterday however the RCD kept tripping. Electrician was called and he said the fault was with the floor sander which was potentially dangerous hence RCD trip. To illustrate this he switched the smaller sanders, kettle etc on and no tripping. But as soon as he plugged the large sander in, the RCD tripped.
The floorer took the sander home and has just called to say the sander is working perfectly with no tripping issues.
Who is right? There's 150. 00 of electricisns bills riding on this. The floorer is blaming my fuse box.

 

[DetlefSchmitz]

Well... He may not have an RCD at home. If he does, it may be a marginal thing where he doesn't not have as much other leakage going on in his house so can get away with it there. You RCD may be more sensitive than his and still be in spec. Did the electrician check the RCD performance in your house, with a tester?

 

[oldbutnotdead]

Not much of an electrician if he didn't have a Megger or similar to test the sander and/or an RCD tester. That would have given you a definitive answer rather than a shoddy plug it in and it trips

 

[simonpdl]

Thankyou for both replies. To be honest I don't know if he did an RCD check or not. Is there anyway I can reduce the chances of it tripping. Unplug other devices? Sorry if this sounds terribly ignorant! Sanding due to resume on Monday and don't want same thing to happen again!

 

[DetlefSchmitz]

Maybe ask a neighbour if they would be ok with your running an extension cable from their supply if it turns out you need to. It's disappointing that the electrical didn't do more to narrow this down.

Not that it helps you, but it strikes me that you can buy an earth leakage clamp meter for about the same price as one visit from an electrician.

 

[simonpdl]

If the large sander was working fine for two days, why would it start to trip the electrics? Sorry for the ignorant question.
BTW the electrician said that the sander was dangerous, and that is what was causing the trip ie a loose wire internally probably. Is this just bull as well?

 

[DetlefSchmitz]

It doesn't sound like the 'electrician' measured the earth leakage from the sander, or tested how much earth leakage the RCD required to trip. Testing by plugging different things in is the sort of thing you can do without an electrician, so you should expect him to do more than that. To put this into perspective for you, many items in a house have a certain level of earth leakage (especially electronic items). The RCD can trip at a leakage current as little as 15mA. When the sum total of these leakages exceeds the value that trips the RCD, it will trip. So in that case everything depends what is plugged in at the time.
Or, as you say, the sander could have a loose wire. A decent electrician should have been able to give you an answer, because you had a repeatable situation which he could have applied measurements to.

 

[KenGMac]

Question? was the sander attached to a wall socket? or was it attached to the cooker socket that generally has a higher rating?

 

[DetlefSchmitz]

Question? was the sander attached to a wall socket? or was it attached to the cooker socket that generally has a higher rating?

Did you notice that it was the RCD that tripped? They don't come in higher ratings.

 

[simonpdl]

It was attached the wall socket. It was the RCD that tripped. The electrician said that both RCD'S had tripped when he tested the sander in different sockets