Correct Type-S Upfront RCD for 3Ph TT System | on ElectriciansForums
Click here to remove these ads

Correct Type-S Upfront RCD for 3Ph TT System

Post new thread

Discuss Correct Type-S Upfront RCD for 3Ph TT System in the UK Electrical Forum area at ElectriciansForums.net

Raptor0014

Raptor0014

Joined
Jan 30, 2021
Messages
491
Reaction score
1,261
Location
Shropshire
Hi all,

Doing an EICR on a property which is 3Ph in and then 3 x Single phase boards from that. However it's on a TT System and doesn't have a upfront 100mA RCD and I am not aware of any reason why one wouldn't be required.

So I am just wondering if this MCG one will suffice into an enclosure.


Or if I need to go balls to the wall and get this Hager one

www.cef.co.uk

100A 4 Pole 100mA Type A RCD

All RCDs have trip free mechanisms and can be padlocked either On or Off
www.cef.co.uk

Obviously I need to justify to the client the cost difference and brand name I know Hager is great kit. But if anyone has any other recommendations it would be appreciated.
 
Sort by date Sort by votes
suffolkspark said:
The MCG one appears to be time delayed type AC, hager seems to be non time delayed type A

I'd want to fit a time delayed type A really, but you also need to be sure the down stream boards have non time delayed rcds upfront, or rcbos with switched neutral
Click to expand...
Good spot on the non-time delay. Never noticed that at first after I got sidetracked at the price. 😂

The downstream boards are 2 x Hager split load dual 30mA RCD

The third board is a fuse box RCBO board
 
Last edited:
Upvote 0 Downvote
Raptor0014 said:
Good spot on the non-time delay. Never noticed that at first after I got sidetracked at the price. 😂

The downstream boards are 2 x Hager split loaf dual 30mA RCD

The third board is a fuse box RCBO board
Click to expand...

Ok, so you need to make sure those fusebox rcbos are switched neutral, if not, in the event of a N-E fault the neutral will still remain in circuit after the rcbo has tripped, likely taking out the big boy upfront
 
Upvote 0 Downvote
suffolkspark said:
The miniature ones are AFAIK, don't know about the full height ones though.
Click to expand...
The full height are too.
[ElectriciansForums.net] Correct Type-S Upfront RCD for 3Ph TT System
 
Upvote 0 Downvote
Raptor0014 said:
I am right is thinking it has to be a time delayed RCD upfront and not just a 100mA or 300mA?
Click to expand...
Yes it would need to be time delayed... but looking at that, if both hager boards out of shot below the head are plastic, I'd just swap out that switch fuse for a new one and fit a 2pole 100ma type S / type A in there as that things got basic insulation hanging out it's arse anyway.
 
Upvote 0 Downvote
suffolkspark said:
Yes it would need to be time delayed... but looking at that, if both hager boards out of shot below the head are plastic, I'd just swap out that switch fuse for a new one and fit a 2pole 100ma type S / type A in there as that things got basic insulation hanging out it's arse anyway.
Click to expand...
I've got that and a lot lot more coded on the EICR 👍

I thought the tails needed to be protected regardless if the CU was plastic (they are)? Hence going to swap out the basic isolator and make that a 3P 100a 100mA time delayed RCD?

Or have I got that wrong?
 
Upvote 0 Downvote
Raptor0014 said:
So I will use something like this (found a type A time delay) which I will put in a separate enclosure to replace that 100A isolator.

www.cef.co.uk

100A 4 Pole 100mA Type A Time Delay RCD

Test button
www.cef.co.uk
Click to expand...

If those fusebox rcbos aren't switched neutral your gonna have a problem....

The tails appear to all be visible there so I wouldn't add upfront rcd protection to anything other than the submain going off to the kitchen.
 
Upvote 0 Downvote
suffolkspark said:
If those fusebox rcbos aren't switched neutral your gonna have a problem....

The tails appear to all be visible there so I wouldn't add upfront rcd protection to anything other than the submain going off to the kitchen.
Click to expand...
They are definitely DP as they're the mini ones.

I'm a little confused as to why you say a upfront for the whole system isn't required? I was led to believe when I did my course (granted I think 'guru graham' as I used to call him was good at passing off his thoughts as a regulation sometimes) that on a TT it must have upfront RCD to protect the tails regardless.

I need to make sure this one has no hiccups as it will be looked at by my CPS assessor so that I can pay for the privilege of being a member for another year....

So I am not questioning your judgement. I just need to know how that fits into the regs as my understanding is its a no ifs, buts or maybes. But could be the way I've had it explained.
 
Upvote 0 Downvote

Reply to Correct Type-S Upfront RCD for 3Ph TT System in the UK Electrical Forum area at ElectriciansForums.net

Similar Threads

F
TT System Existing is a multi9 13 way RCD main switch DB
Regarding the EV, it’s an Ohme charger which I believe has a type A RCD built in, setup would be: 50A RCBO to feed garage db Garage db has no...
Replies
17
Views
529
fattony
F
U
  • Question
TT system EICR questions
I think there is a little truth in what the guy in the video says, but he makes more out of it than he should. A N-E fault on a circuit protected...
2
Replies
28
Views
1K
Pretty Mouth
Pretty Mouth
T
  • Question
SPD Mains Isolator wylex/Proteus
According to google search, a Buzz Bar is a convenient, pocket-size disposable vape device The way my guesses have worked out lately, I would...
Replies
20
Views
4K
mainline
mainline
B
  • Question
UK RCD Protecting Distribution Cables on a TT on Industrial Estate
much more information required. Is the supply to the first building a DNO supply or a sub main cable from another building ? if it is a sub main...
Replies
5
Views
834
MDJ
MDJ
woodster92
Help with Reg 551.7.2 Ina >= In + Ig(s) on 3 Phase Supply
Just stick the 63amp fused connector before the Henley block , or Lucy block as you call it, and your all good, as for your 2nd point, , the...
Replies
1
Views
667
Upton Sparks
Upton Sparks

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

Tilers Community
This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
NHS Forums | Forum for NHS Staff and NHS Patients
Back
Top
✖
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock    No Thanks