RCD types

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Anyone else getting headaches over the plethora of different RCD types now available .............. and the decided lack of decent straight forward information about their selection and use?

 
It does get complicated . 

Type AC

Detects AC sinusoidal residual current only .

Type A.

Alternating sinusoidal residual and residual pulsating DC suddenly applied or smoothly increasing.

Type F .

Responds to HF residual current  & pulsating DC  current .

Type  B

Responds to all types of residual current including smooth DC . 

 
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It does get complicated . 

Type AC

Detects AC sinusoidal residual current only .

Type A.

Alternating sinusoidal residual and residual pulsating DC suddenly applied or smoothly increasing.

Type F .

Responds to HF residual current  & pulsating DC  current .

Type  B

Responds to all types of residual current including smooth DC . 
quite - but how many people know this?

just waiting to see my first EICR handing out C2’s for having the wrong ones ....

 
With all these new fan-dangled inverter driven appliances and chargers, LEDs, TVs etc being plugged in leaking DC current and DC current masking type AC RCDs, I believe any new consumer unit should be fitted with type A RCDs/RCBOs to future proof against this. As mentioned above the problem is on the shelf stock and some wholesalers not having the knowledge, "an RCD is an RCD isn't it".

The EV chargers require a specific type as well but can't remember which. 

 
It does get complicated . 

Type AC

Detects AC sinusoidal residual current only .

Type A.

Alternating sinusoidal residual and residual pulsating DC suddenly applied or smoothly increasing.

Type F .

Responds to HF residual current  & pulsating DC  current .

Type  B

Responds to all types of residual current including smooth DC . 


so what do we get over the counter at Joe Bloggs wholesalers? 

Trying to think whre you would use a Type F? 

 
The usual  jobby is a type  AC   as far as I know . 

Has anyone yet to fit any of the other types yet. ?

We have now left fuse wire  soooo far behind  have we not ? 

 
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That brought back a memory of the common conception about fuses .     

" The fuse keeps blowing so I 've put bigger wire in it "  !!!

Theres still one fusewire board  left at the printer I look after  ,  I've been pushing  to upgrade it for the last 20 yrs  but its down to  budget.    

DB1.jpg

 
That brought back a memory of the common conception about fuses .     

" The fuse keeps blowing so I 've put bigger wire in it "  !!!

Theres still one fusewire board  left at the printer I look after  ,  I've been pushing  to upgrade it for the last 20 yrs  but its down to  budget.    

View attachment 11044
Not seen a set of wooden stepladders for 20 years in a factory either 

 
Not seen a set of wooden stepladders for 20 years in a factory either 
Probably not ,  they're  from the top of my van  !!   I've had them for 30 yrs .  

Like Trigger's Broom  they've had new treads , new ropes , new hinges  etc.   

Even worse  ,  as we pan back ,  OMG!   Metal steps !! Call The HSE !!

DB1 Bindery.jpg

 
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The aluminium ladder reminds me of an amusing, (but could have been tragic!) incident some years ago. 

Visiting my newsagent, who I was on friendly terms with, I was greeted with, "Geoff, can you spare two minutes to tell me what I'm doing wrong with the lounge light?"

We went through the back of the shop to the accommodation.  He was trying to reinstall a fancy fitting with the usual loop in connections, having decorated the room. Like many before him he had mixed up the connections and was using trial and error to try to get it working again. 

Picture this though:

To finish off the decorating he had shampooed  the carpet, quite enthusiastically I think, because it was like walking on wet grass. Because he didn't want to mark his newly cleaned carpet he had then taken his shoes off, so is now wearing wet socks. In the centre of the room was a pair of aluminium step ladders from which he was carrying out his experimentation. 

I did point to him what he was doing wrong.

 
Geoff's post reminded me of an incident some years ago just up the road from me, a builder mate rang me, 'can you get over here quick, the plasterer has sparks coming off the ceiling' he told me, sounding very excited. I jumped in my van and went round to the house, the plasterer had started to skim a ceiling, it was a typical bodge job, leave the light fitting up and skim aorund it, you've all seen them.

Well it was all going well until he came to the plaster around the fitting, a large brass three arm thing, he'd felt a couple of tingles as he'd been putting the plaster on the ceiling but ignored it, then he'd seen a couple of flashes. I tested from a neutral at a socket to the metal of the fitting, 240v! It would even light a test lamp with a 15W lamp in it.

I turned off the power and removed the fitting, there was no earth on the main cables, they were the old twin type, so we had live in, live out, connected with the ubiquitous terminal block, neutral in and out, connected in the same manner, we then had the switch wire, red into the live in and out, and black to the fitting (no sleeving).on the fitting we had a brown, a blue and a green/yellow, the blue went to the neutral, the brown to the switch wire (single black) and the earth went to the 3 reds (loop live)!

At this point the customer walks in and asks what all the fuss is about, 'that fitting has been in for years mate, fitted it myself and we've never had a shock off it, in fact the wife wipes it with a damp cloth every weekend' . The reason he'd stuck the earth in with the lives was because he 'knew it had to go somewhere and that was the only spare wires he could connnect it to' ,it's amazing that a good carpet (foam backed) and a pair of wooden steps can give such a good level of insulation, otherwise he could have ended up with a dead wife!

Believe it or not I had an identical fault a couple of weeks later, a freind of my wife's was moving home and wanted all her fancy lights taking down and replacing with pendants so she cold take them with her to the new house, ' you shouldn't have any problems, I fitted them myself so they were done properly' she proudly informed me. The first fitting I removed was a large brass chandelier in the lounge, again the supply cables were the old twins with no earth, and once again the earth had been connected to the loop live.

 
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