ECN Forum Forums Code Related Discussion NEC & other Code issues Outbuilding grounding

I suppose ( hack...choke...pitouwee...)your right

There has been equal concern about a pad mount utility x-former feeding (same 3-wire) to a meter. Think of it within reaching distance, hot summer day, sweaty palms
.....sure makes your isolated nuetral look good!

Point taken. I woudn't want to be leaning against that service conduit if the neutral went open at the pole.


Swings & roundabouts, I think. It's great with the old town systems with ground via the cable armor, but not so good on rural overhead services where you're then relying on just the local rod for grounding everything.

That's when we start getting involved with a whole-house GFI. My biggest gripe with this arrangement is that a simple ground fault on one branch takes out the entire supply to the building. The older systems have those awful voltage ELCBs I've complained about.

It's after struggling with one of these that PME with bonded N & G looks very attractive!

Going onto a slightly different angle on my original query, what neutral/grounding arrangement is used on the distribution within a mobile home park?

Hi Paul;
mobile homes are all 4-wire ( isolated neutral) feeders here.

the term 'feeder' meaning after the main disco

Similar situation here: The PME system used in some houses is not employed on mobile homes, so it's always a 3-wire cable throughout (only one hot leg, remember).

When you say the main disconnect, do you mean the main at the site service panel or the main disconnect at each mobile home? In other words, is it 3-wire with combined N/G up to the post serving each home then separate N/G, or 4-wire right back to the site's service entrance?

Paul;
the 3 wire ( H,H N&G ) would be up to the first disco as fed by the utility, 4 wire afterwards, regardless of how many disco's in one power line.

Gotcha. Pretty much the same N/G isolation as we have on mobile home parks then.

From the earlier discussion about outbuildings, I assume that you also drive a separate ground rod at each home paralleled up to the feeder ground wire.
Do you also bond the chassis/body to the ground busbar?

Come to think of it, I know that aluminum siding is popular on regular homes there. Is that normally bonded as well?

Paul;
normally G-rods would be @ the disco only. A mobile home disco is required within 30'(but not on) a mobile home here. That's where we bond the GEC and the rods.

there has been some discussion on this that get's rather flamed, but that's usually the norm here.....

this is a very good example of theory, terminology and NEC intent not having a harmonious existence in 250-32 .

the was, the last cycle (99') an ad-hoc committee that turned 250 inside out. i think thier goal was to clean it up, there is now a cross reference guide in the back for all the changes. i guess they tried....but it still reads hard

oops,,
forgot your other Q,

yes the chasis is bonded to the MH panels G-bar, this in turn bonds al other connecting metal

Thanks Sparky.

Our IEE Regs. always seem a bit vague to me when it comes to mobile homes (or "caravans" in British terminology).

The section on caravans specifies that where twin & earth (Romex) is run along chassis members there must be an insulating material between them. They also specify that the main earth terminal at the intake be insulated from the chassis, which tends to suggest that they would like the body completely separated from the grounding system.

This seems to be totally at odds with the regs. in the general section on earthing which state that all extraneous metalwork must be bonded to the main earth bar.

The confusing thing about the caravan section is that when it comes to a bath or shower compartment, they switch to "bond everythng" mode, which means that the whole body is likely to be grounded indirectly via this bonding anyway.

See, it's not just the NEC which can be vague...