Myths of the Trade 4

[Evans Electric]

An RCD rated at ,say , 30 amps/ 30mA gives overload protection at 30 amps !!

Have met at least 3 guys who insisted that this is the case. One chap was wiring showers for a plumber, 6mm meter tails out of the main switch to a 30a/30mA RCD , then 6mm T/E off to the shower. Shower protected by a 100amp HRC fuse, theres lovely, isn't it.

 

[Andy™]

i think the main problem here is many RCD's have a current rating on the,. i.e 30mA 40A. plumbers and the like see this 40A to be its tripping current. in reality it just means the RCD is designed to carry 40A, so will probably not work too well on 80A.

 

[batty]

Yes met one of these on a job Rcd fed from tails then swa out to what used to feed a hot tub in garden at least they had used a garage supply to feed hot tub but who does these jobs must have been the guy that fitted tub. i have seen this to many times. A little knowledge is a dangerous thing.

Batty

 

[Riggy]

I've had the opposite (sort of).

I was doing a PIR on a caravan site, lots of failed RCDs. Swapping one when the guy using the pitch turns up ("used to be a Spark before I retired, 40 years on the trade" - you know the type). Went mad because I was fitting a 40A 30mA RCD feeding "his" 16A socket (via a 10A MCB) adamant I was a cowboy out to kill him!

 

[Apache]

Even I know a RCD has no overload protection! Do you think it's RCBO's clouding peoples perception of what a RCD/MCB/RCBO actually does?

 

[Apache]

I've had the opposite (sort of).I was doing a PIR on a caravan site, lots of failed RCDs. Swapping one when the guy using the pitch turns up ("used to be a Spark before I retired, 40 years on the trade" - you know the type). Went mad because I was fitting a 40A 30mA RCD feeding "his" 16A socket (via a 10A MCB) adamant I was a cowboy out to kill him!

Why feed a 16A socket from 10A MCB?

:|

 

[batty]

Even I know a RCD has no overload protection! Do you think it's RCBO's clouding peoples perception of what a RCD/MCB/RCBO actually does?

No just people with a little knowledge but no real understanding of electrics.

Batty

 

[Apache]

No just people with a little knowledge but no real understanding of electrics.Batty

Think you a right there

 

[batty]

Why feed a 16A socket from 10A MCB? :|

This is how caravan site boxes are generally made up they assesss that 10 amps should be adequate for most vans.

Batty

 

[Apache]

This is how caravan site boxes are generally made up they assesss that 10 amps should be adequate for most vans.Batty

I do appreciate you taking the time to explain these things Batts

Thanks

 

[batty]

I do appreciate you taking the time to explain these things Batts Thanks

Thank you not a problem.

 

[Andy™]

Why feed a 16A socket from 10A MCB? :|

depending on site, there is not normally enough to give 16A per site. so a lower rated MCB is used. although if everyone used the 10A, it would probably overload the main site incomer

 

[Riggy]

Why feed a 16A socket from 10A MCB? :|

Apache,

Batty and Andyc are both bang on. Generally use high diversity on caravan site anyway (imagine if you didn't, 100 outlets at 16A each!). 10A is suitable for most vans and strikes a reasonable balance between user needs and owner costs

 

[Evans Electric]

Thank you not a problem. [/quoteThis weeks award for politeness in the face of the enemy goes to

Batty and ApacheApplaud SmileyApplaud SmileyApplaud SmileyApplaud Smiley

 

[binky]

An RCD rated at ,say , 30 amps/ 30mA gives overload protection at 30 amps !! Have met at least 3 guys who insisted that this is the case. One chap was wiring showers for a plumber, 6mm meter tails out of the main switch to a 30a/30mA RCD , then 6mm T/E off to the shower. Shower protected by a 100amp HRC fuse, theres lovely, isn't it.

Have seen a local spark do this too :O:O:O

 

[Andy™]

just remembered about this

 

[Theorysparky]

thats just lazy...