• Welcome to the new forum. We're now hosted on ElectriciansForums.net rather than ElectriciansForums.co.uk - Chat about the forum upgrade by CLICKING HERE

Welcome to our Electrical Forum - We started out providing electrical advice just for the UK - But now we have specific advice for the USA too! - Register for free and share American Electrical Advice.

Discuss FICA multiple choice help in the Electrical Courses & Electrical NVQ's area at ElectriciansForums.net

Weeloon

New EF Member
Hi, I am resitting my FICA Underpinning Knowledge test next week and I stuck on a few questions in the mock tests they have on their website. I have been doing a lot of revision but my brain has gone to mush. Can anyone help with the following question?

Question - The maximum earth fault loop impedance for a 16A BS 88-3 fuse system C for a 5s disconnection time with a U of 230V is

A 5.08
B 3.9
C 3.2
D 3.64

They give you the answer but not how the answer is reached.

Many thanks in advance for any help given.
 

westward10

In echoed steps I walk across an empty dream.
Staff member
Moderator
These are maximum values of Zs, where would you normally find these?
There is no calculation required.
 

Sintra

The Innkeeper
Staff member
Admin
Fig 3A1 in BS7671 shows that a 16A BS88-3 fuse system C takes 56A to disconnect in 5s. Then you can apply the formula given in appendix 3.

Zs =Uo x Cmin / Ia
Zs = 230 x 0.95 / 56
Zs = 3.9 ohms
 

MFS Electrical

Forum Mentor
Good luck with the FICA remember you get books to take in with you for all the questions. As long as you don’t do something daft on the install you should be good I shorted the motor starter to earth on the backbox :rolleyes: and still passed so don’t be too worried
 

Electrician Talk

Electrical 2 Go - Electrical Supplier and Electrical Wholesalers
Electrical Insurance
ElectriciansForums.net (formerly known as ElectriciansForums.co.uk) was setup in April 2006 to provide free electrical advice to both professional and DIY electricians. Whether seeking advice for auto electrics, trying to find electrical installation condition reports (EICR) form downloads, or whether you're here just to talk to other electricians; we've been a first-choice website for tens of thousands of sparkies for well over a decade.
Top